10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q

(Mark one)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 or 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the Quarterly Period Ended September 30, 2023

or

☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.

For the Transition Period from                      to                     .

Commission File Number 1-15202

W. R. BERKLEY CORPORATION

(Exact name of registrant as specified in its charter)

Delaware			22-1867895
(State or other jurisdiction of incorporation or organization)			(I.R.S. Employer Identification No.)
475 Steamboat Road	Greenwich	Connecticut	06830
(Address of principal executive offices)			(Zip Code)

(203) 629-3000

(Registrant’s telephone number, including area code)

	None
Former name, former address and former fiscal year, if changed since last report.

Securities registered pursuant to Section 12(b) of the Act:

Title	Trading Symbol	Name
Common Stock, par value $.20 per share	WRB	New York Stock Exchange
5.700% Subordinated Debentures due 2058	WRB-PE	New York Stock Exchange
5.100% Subordinated Debentures due 2059	WRB-PF	New York Stock Exchange
4.250% Subordinated Debentures due 2060	WRB-PG	New York Stock Exchange
4.125% Subordinated Debentures due 2061	WRB-PH	New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒     No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒     No ☐

1

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐    No ☒

Number of shares of common stock, $.20 par value, outstanding as of October 30, 2023: 257,872,034

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TABLE OF CONTENTS

Part I — FINANCIAL INFORMATION
	Item 1. Financial Statements
	Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations
	Item 3. Quantitative and Qualitative Disclosure About Market Risk
	Item 4. Controls and Procedures
PART II — OTHER INFORMATION
	Item 1. Legal Proceedings
	Item 1A. Risk Factors
	Item 2. Unregistered Sales of Equity Securities and Use of Proceeds
	Item 5. Other Information
	Item 6. Exhibits
SIGNATURES
EX-31.1
EX-31.2
EX-32.1
EX-101 INSTANCE DOCUMENT
EX-101 SCHEMA DOCUMENT
EX-101 CALCULATION LINKBASE DOCUMENT
EX-101 LABELS LINKBASE DOCUMENT
EX-101 PRESENTATION LINKBASE DOCUMENT
EX-101 DEFINITION LINKBASE DOCUMENT

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Part I — FINANCIAL INFORMATION

Item 1.     Financial Statements

W. R. BERKLEY CORPORATION AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS

(In thousands, except share data)

	September 30, 2023		December 31, 2022
	(Unaudited)		(Audited)
Assets
Investments:
Fixed maturity securities (amortized cost of $20,232,773 and $18,715,483; allowance for expected credit losses of $46,412 and $37,466 at September 30, 2023 and December 31, 2022, respectively)	$	19,035,305	$	17,587,349
Investment funds	1,600,495		1,608,548
Real estate	1,270,545		1,340,622
Equity securities	1,182,061		1,185,894
Arbitrage trading account	825,049		944,230
Loans receivable (net of allowance for expected credit losses of $4,009 and $1,791 at September 30, 2023 and December 31, 2022, respectively)	177,750		193,002
Total investments	24,091,205		22,859,645
Cash and cash equivalents	1,646,074		1,449,346
Premiums and fees receivable (net of allowance for expected credit losses of $33,602 and $30,660 at September 30, 2023 and December 31, 2022, respectively)	3,104,609		2,779,244
Due from reinsurers (net of allowance for expected credit losses of $9,443 and $8,064 at September 30, 2023 and December 31, 2022, respectively)	3,426,196		3,187,730
Deferred policy acquisition costs	854,374		763,486
Prepaid reinsurance premiums	756,236		696,468
Trading account receivables from brokers and clearing organizations	401,982		233,863
Property, furniture and equipment	423,279		423,232
Goodwill	174,597		185,509
Accrued investment income	201,206		166,784
Current and deferred federal and foreign income taxes	291,363		333,774
Other assets	740,227		736,022
Total assets	$	36,111,348	$	33,815,103
Liabilities and Equity
Liabilities:
Reserves for losses and loss expenses	$	18,273,310	$	17,011,223
Unearned premiums	5,899,738		5,297,654
Due to reinsurers	626,448		523,131
Trading account securities sold but not yet purchased	7,538		—
Other liabilities	1,537,449		1,377,740
Senior notes and other debt	1,828,046		1,828,823
Subordinated debentures	1,008,910		1,008,371
Total liabilities	29,181,439		27,046,942
Equity:
Preferred stock, par value $0.10 per share:
Authorized 5,000,000 shares; issued and outstanding - none	—		—
Common stock, par value $0.20 per share:
Authorized 1,250,000,000 shares; issued and outstanding, net of treasury shares, 258,043,531 and 264,546,100 shares, respectively	105,803		105,803
Additional paid-in capital	1,008,301		997,534
Retained earnings	10,800,697		10,161,005
Accumulated other comprehensive loss	(1,322,819)		(1,264,581)
Treasury stock, at cost, 270,971,091 and 264,468,528 shares, respectively	(3,676,403)		(3,251,429)
Total stockholders’ equity	6,915,579		6,748,332
Noncontrolling interests	14,330		19,829
Total equity	6,929,909		6,768,161
Total liabilities and equity	$	36,111,348	$	33,815,103

See accompanying notes to interim consolidated financial statements.

1

W. R. BERKLEY CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(In thousands, except per share data)

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2023		2022		2023		2022
REVENUES:
Net premiums written	$	2,848,459	$	2,577,274	$	8,234,799	$	7,576,163
Change in net unearned premiums	(206,545)		(135,313)		(548,726)		(527,958)
Net premiums earned	2,641,914		2,441,961		7,686,073		7,048,205
Net investment income	270,944		202,816		739,494		547,902
Net investment (losses) gains:
Net realized and unrealized (losses) gains on investments	(40,855)		(66,282)		50,403		139,664
Change in allowance for expected credit losses on investments	(1,571)		(1,128)		(11,164)		(12,365)
Net investment (losses) gains	(42,426)		(67,410)		39,239		127,299
Revenues from non-insurance businesses	137,116		119,013		375,225		345,210
Insurance service fees	22,962		27,940		81,290		82,284
Other income	128		80		235		1,797
Total revenues	3,030,638		2,724,400		8,921,556		8,152,697
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,636,193		1,564,578		4,744,602		4,339,646
Other operating costs and expenses	808,669		725,537		2,457,925		2,139,256
Expenses from non-insurance businesses	133,939		116,240		370,244		334,062
Interest expense	31,888		31,780		95,580		98,473
Total operating costs and expenses	2,610,689		2,438,135		7,668,351		6,911,437
Income before income taxes	419,949		286,265		1,253,205		1,241,260
Income tax expense	(86,519)		(55,791)		(268,322)		(238,290)
Net income before noncontrolling interests	333,430		230,474		984,883		1,002,970
Noncontrolling interests	156		(1,595)		(863)		(4,131)
Net income to common stockholders	$	333,586	$	228,879	$	984,020	$	998,839
NET INCOME PER SHARE:
Basic	$	1.24	$	0.83	$	3.62	$	3.61
Diluted	$	1.23	$	0.82	$	3.59	$	3.57

See accompanying notes to interim consolidated financial statements.

2

W. R. BERKLEY CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED)

(In thousands)

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2023		2022		2023		2022
Net income before noncontrolling interests	$	333,430	$	230,474	$	984,883	$	1,002,970
Other comprehensive loss:
Change in unrealized currency translation adjustments	(22,781)		(40,516)		(7,387)		(27,637)
Change in unrealized investment losses, net of taxes	(118,365)		(315,664)		(50,850)		(1,076,217)
Other comprehensive loss	(141,146)		(356,180)		(58,237)		(1,103,854)
Comprehensive income (loss)	192,284		(125,706)		926,646		(100,884)
Noncontrolling interests	156		(1,595)		(862)		(4,130)
Comprehensive income (loss) to common stockholders	$	192,440	$	(127,301)	$	925,784	$	(105,014)

See accompanying notes to interim consolidated financial statements.

3

W. R. BERKLEY CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (UNAUDITED)

(In thousands, except per share data)

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2023		2022		2023		2022
COMMON STOCK:
Beginning and end of period	$	105,803	$	105,803	$	105,803	$	105,803
ADDITIONAL PAID-IN CAPITAL:
Beginning of period	$	1,020,818	$	1,001,093	$	997,534	$	981,104
Restricted stock units issued	(25,226)		(28,381)		(25,228)		(30,751)
Restricted stock units expensed	12,709		12,091		35,995		34,450
End of period	$	1,008,301	$	984,803	$	1,008,301	$	984,803
RETAINED EARNINGS:
Beginning of period	$	10,624,518	$	9,602,948	$	10,161,005	$	9,015,135
Net income to common stockholders	333,586		228,879		984,020		998,839
Dividends ($0.61, $0.10, $1.32 and $0.79 per share, respectively)	(157,407)		(26,590)		(344,328)		(208,737)
End of period	$	10,800,697	$	9,805,237	$	10,800,697	$	9,805,237
ACCUMULATED OTHER COMPREHENSIVE LOSS:
Unrealized investment (loss) gain:
Beginning of period	$	(825,391)	$	(669,654)	$	(892,905)	$	90,900
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(108,121)		(311,659)		(47,757)		(1,055,628)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses	(10,244)		(4,005)		(3,094)		(20,590)
End of period	(943,756)		(985,318)		(943,756)		(985,318)
Currency translation adjustments:
Beginning of period	(356,282)		(359,976)		(371,676)		(372,855)
Net change in period	(22,781)		(40,516)		(7,387)		(27,637)
End of period	(379,063)		(400,492)		(379,063)		(400,492)
Total accumulated other comprehensive loss	$	(1,322,819)	$	(1,385,810)	$	(1,322,819)	$	(1,385,810)
TREASURY STOCK:
Beginning of period	$	(3,682,281)	$	(3,165,729)	$	(3,251,429)	$	(3,167,076)
Stock exercised/vested	8,469		8,332		9,461		9,679
Stock repurchased	(2,917)		(6,570)		(430,536)		(6,570)
Other	326		—		(3,899)		—
End of period	$	(3,676,403)	$	(3,163,967)	$	(3,676,403)	$	(3,163,967)
NONCONTROLLING INTERESTS:
Beginning of period	$	21,167	$	22,388	$	19,829	$	14,719
(Distributions) contributions	(6,681)		(73)		(6,361)		5,061
Net (loss) income	(156)		1,595		863		4,131
Other comprehensive loss, net of tax	—		—		(1)		(1)
End of period	$	14,330	$	23,910	$	14,330	$	23,910

See accompanying notes to interim consolidated financial statements.

4

W. R. BERKLEY CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(In thousands)

	For the Nine Months Ended September 30,
	2023		2022
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$	984,020	$	998,839
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(39,239)		(127,299)
Depreciation and amortization	3,294		46,037
Noncontrolling interests	863		4,131
Investment funds	(5,444)		(121,919)
Stock incentive plans	37,796		36,247
Change in:
Arbitrage trading account	(41,399)		(39,389)
Premiums and fees receivable	(340,056)		(247,782)
Reinsurance accounts	(194,610)		(187,453)
Deferred policy acquisition costs	(93,270)		(92,724)
Income taxes	49,722		(111,231)
Reserves for losses and loss expenses	1,288,975		1,225,679
Unearned premiums	608,300		551,894
Other	(27,790)		(161,727)
Net cash from operating activities	2,231,162		1,773,303
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	877,019		1,638,049
Proceeds from sale of equity securities	161,470		20,057
Distributions from (contributions to) investment funds	8,385		(72,925)
Proceeds from maturities and prepayments of fixed maturity securities	2,654,140		3,916,331
Purchase of fixed maturity securities	(5,091,866)		(7,694,663)
Purchase of equity securities	(63,815)		(340,158)
Real estate additions	(15,158)		(18,670)
Change in loans receivable	12,796		2,066
Net purchases of property, furniture and equipment	(42,127)		(35,270)
Change in balances due to security brokers	8,224		177,457
Cash received in connection with business disposition	94,076		906,789
Payment for business purchased net of cash acquired	—		(49,572)
Other	320		94
Net cash used in investing activities	(1,396,536)		(1,550,415)
CASH USED IN FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(1,954)		(426,503)
Net proceeds from issuance of debt	1,100		2,181
Cash dividends to common stockholders	(186,921)		(182,147)
Purchase of common treasury shares	(430,536)		(6,570)
Other, net	(20,545)		(21,808)
Net cash used in financing activities	(638,856)		(634,847)
Net impact on cash due to change in foreign exchange rates	959		(26,134)
Net change in cash and cash equivalents	196,728		(438,093)
Cash and cash equivalents at beginning of period	1,449,346		1,568,843
Cash and cash equivalents at end of period	$	1,646,074	$	1,130,750

See accompanying notes to interim consolidated financial statements.

5

W. R. Berkley Corporation and Subsidiaries

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

(1) General

    The unaudited consolidated financial statements, which include the accounts of W. R. Berkley Corporation and its subsidiaries (the “Company”), have been prepared on the basis of U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. Reclassifications have been made in the 2022 financial statements as originally reported to conform to the presentation of the 2023 financial statements. For the for nine months ended September 30, 2022, the Company did not correct the proceeds from sale of fixed maturity securities and purchase of fixed maturity securities lines within the consolidated statements of cash flows for an incremental inter-company elimination as the effects were not material and had no impact on the total amount of investing activities.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the revenues and expenses reflected during the reporting period. For further information related to areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective income tax rate differs from the federal income tax rate of 21% primarily due to tax benefits related to equity-based compensation and tax-exempt investment income, which was partially offset by state income taxes.

(2) Per Share Data

    The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 11,416,856 and 11,592,699 common shares held in a grantor trust as of September 30, 2023 and 2022, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.

    The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:

	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(In thousands)	2023	2022	2023	2022
Basic	269,191	277,192	271,656	276,928
Diluted	271,439	279,642	274,146	279,644

(3) Recent Accounting Pronouncements and Accounting Policies

Recently adopted accounting pronouncements:

    All accounting and reporting standards that became effective in 2023 were either not applicable to the Company or their adoption did not have a material impact on the Company.

6

Accounting and reporting standards that are not yet effective:

    All recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

7

(4) Consolidated Statements of Comprehensive (Loss) Income

    The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"):

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(892,905)		$	(371,676)	$	(1,264,581)
Other comprehensive loss before reclassifications	(103,087)			(7,387)		(110,474)
Amounts reclassified from AOCI	52,237			—		52,237
Other comprehensive loss	(50,850)			(7,387)		(58,237)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	66,123	(1)	$	—	$	66,123
Tax effect	(13,886)		(2)	—		(13,886)
After-tax amounts reclassified	$	52,237		$	—	$	52,237
Other comprehensive loss
Pre-tax	$	(62,476)		$	(7,387)	$	(69,863)
Tax effect	11,626			—		11,626
Other comprehensive loss	$	(50,850)		$	(7,387)	$	(58,237)
As of and for the three months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(825,391)		$	(356,282)	$	(1,181,673)
Other comprehensive loss before reclassifications	(133,018)			(22,781)		(155,799)
Amounts reclassified from AOCI	14,653			—		14,653
Other comprehensive loss	(118,365)			(22,781)		(141,146)
Unrealized investment loss related to noncontrolling interest	—			—		—
Ending balance	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	18,548	(1)	$	—	$	18,548
Tax effect	(3,895)		(2)	—		(3,895)
After-tax amounts reclassified	$	14,653		$	—	$	14,653
Other comprehensive loss
Pre-tax	$	(150,455)		$	(22,781)	$	(173,236)
Tax effect	32,090			—		32,090
Other comprehensive loss	$	(118,365)		$	(22,781)	$	(141,146)

8

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2022
Changes in AOCI
Beginning of period	$	90,900		$	(372,855)	$	(281,955)
Other comprehensive loss before reclassifications	(1,134,657)			(27,637)		(1,162,294)
Amounts reclassified from AOCI	58,440			—		58,440
Other comprehensive loss	(1,076,217)			(27,637)		(1,103,854)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	73,975	(1)	$	—	$	73,975
Tax effect	(15,535)		(2)	—		(15,535)
After-tax amounts reclassified	$	58,440		$	—	$	58,440
Other comprehensive loss
Pre-tax	$	(1,365,064)		$	(27,637)	$	(1,392,701)
Tax effect	288,847			—		288,847
Other comprehensive loss	$	(1,076,217)		$	(27,637)	$	(1,103,854)
As of and for the three months ended September 30, 2022
Changes in AOCI
Beginning of period	$	(669,654)		$	(359,976)	$	(1,029,630)
Other comprehensive loss before reclassifications	(335,034)			(40,516)		(375,550)
Amounts reclassified from AOCI	19,370			—		19,370
Other comprehensive loss	(315,664)			(40,516)		(356,180)
Unrealized investment loss related to noncontrolling interest	—					—
Ending balance	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	24,519	(1)	$	—	$	24,519
Tax effect	(5,149)		(2)	—		(5,149)
After-tax amounts reclassified	$	19,370		$	—	$	19,370
Other comprehensive loss
Pre-tax	$	(394,832)		$	(40,516)	$	(435,348)
Tax effect	79,168			—		79,168
Other comprehensive loss	$	(315,664)		$	(40,516)	$	(356,180)

____________

(1) Net investment (losses) gains in the consolidated statements of income.

(2) Income tax expense in the consolidated statements of income.

(5) Statements of Cash Flows

    Interest payments were $79,336,000 and $115,756,000 for the nine months ended September 30, 2023 and 2022, respectively. Income taxes paid were $180,000,000 and $263,971,000 for the nine months ended September 30, 2023 and 2022, respectively.

9

(6) Investments in Fixed Maturity Securities

    At September 30, 2023 and December 31, 2022, investments in fixed maturity securities were as follows:

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
September 30, 2023
Held to maturity:
State and municipal	$	49,847	$	(48)	$	1,825	$	—	$	51,624	$	49,799
Residential mortgage-backed	3,029		—		19		—		3,048		3,029
Total held to maturity	52,876		(48)		1,844		—		54,672		52,828
Available for sale:
U.S. government and government agency	1,546,889		—		2,077		(81,767)		1,467,199		1,467,199
State and municipal:
Special revenue	1,771,219		—		2,287		(126,585)		1,646,921		1,646,921
State general obligation	378,650		—		1,247		(23,727)		356,170		356,170
Pre-refunded	103,219		—		202		(827)		102,594		102,594
Corporate backed	194,976		(821)		159		(14,341)		179,973		179,973
Local general obligation	401,286		—		1,767		(17,713)		385,340		385,340
Total state and municipal	2,849,350		(821)		5,662		(183,193)		2,670,998		2,670,998
Mortgage-backed:
Residential	1,660,790		(24)		399		(214,381)		1,446,784		1,446,784
Commercial	651,966		(2,076)		11		(20,389)		629,512		629,512
Total mortgage-backed	2,312,756		(2,100)		410		(234,770)		2,076,296		2,076,296
Asset-backed	4,197,235		(1,502)		750		(109,025)		4,087,458		4,087,458
Corporate:
Industrial	3,567,020		—		5,026		(227,479)		3,344,567		3,344,567
Financial	2,813,603		(5,406)		1,362		(130,312)		2,679,247		2,679,247
Utilities	683,468		(364)		164		(39,991)		643,277		643,277
Other	593,466		—		134		(11,877)		581,723		581,723
Total corporate	7,657,557		(5,770)		6,686		(409,659)		7,248,814		7,248,814
Foreign government	1,616,110		(36,171)		1,361		(149,588)		1,431,712		1,431,712
Total available for sale	20,179,897		(46,364)		16,946		(1,168,002)		18,982,477		18,982,477
Total investments in fixed maturity securities	$	20,232,773	$	(46,412)	$	18,790	$	(1,168,002)	$	19,037,149	$	19,035,305

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

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(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
December 31, 2022
Held to maturity:
State and municipal	$	47,802	$	(114)	$	4,239	$	—	$	51,927	$	47,688
Residential mortgage-backed	3,608		—		38		—		3,646		3,608
Total held to maturity	51,410		(114)		4,277		—		55,573		51,296
Available for sale:
U.S. government and government agency	960,479		—		937		(69,158)		892,258		892,258
State and municipal:
Special revenue	1,837,309		—		3,662		(119,474)		1,721,497		1,721,497
State general obligation	387,709		—		2,651		(21,335)		369,025		369,025
Pre-refunded	156,106		—		2,741		(7)		158,840		158,840
Corporate backed	210,228		—		334		(10,923)		199,639		199,639
Local general obligation	454,983		—		2,967		(16,853)		441,097		441,097
Total state and municipal	3,046,335		—		12,355		(168,592)		2,890,098		2,890,098
Mortgage-backed:
Residential	1,308,019		(18)		395		(171,595)		1,136,801		1,136,801
Commercial	547,757		—		215		(19,363)		528,609		528,609
Total mortgage-backed securities	1,855,776		(18)		610		(190,958)		1,665,410		1,665,410
Asset-backed	4,132,365		—		2,730		(152,322)		3,982,773		3,982,773
Corporate:
Industrial	3,491,645		(1,704)		4,439		(241,381)		3,252,999		3,252,999
Financial	2,585,247		(2,997)		5,505		(117,383)		2,470,372		2,470,372
Utilities	586,066		—		1,307		(36,325)		551,048		551,048
Other	441,230		—		—		(11,657)		429,573		429,573
Total corporate	7,104,188		(4,701)		11,251		(406,746)		6,703,992		6,703,992
Foreign government	1,564,930		(32,633)		4,283		(135,058)		1,401,522		1,401,522
Total available for sale	18,664,073		(37,352)		32,166		(1,122,834)		17,536,053		17,536,053
Total investments in fixed maturity securities	$	18,715,483	$	(37,466)	$	36,443	$	(1,122,834)	$	17,591,626	$	17,587,349

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	114	$	387
Provision for expected credit losses	(66)		(266)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	53	$	127
Provision for expected credit losses	(5)		(6)
Allowance for expected credit losses, end of period	$	48	$	121

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The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	32,633	$	4,701	$	18	$	—	$	—	$	37,352	$	22,222	$	16	$	—	$	22,238
Expected credit losses on securities for which credit losses were not previously recorded	—		942		1,766		1,444		821		4,973		1,897		1,205		21		3,123
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,538		134		316		58		—		4,046		9,289		(22)		—		9,267
Reduction due to disposals	—		(7)		—		—		—		(7)		(33)		—		—		(33)
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. During the nine months ended September 30, 2022, the Company increased the allowance for expected credit losses for available for sale securities mainly due to an increase in unrealized losses primarily associated with foreign government securities.

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	33,052	$	8,867	$	885	$	1,444	$	—	$	44,248	$	33,096	$	182	$	—	$	33,278
Expected credit losses on securities for which credit losses were not previously recorded	—		756		905		—		821		2,482		—		1,023		21		1,044
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,119		(3,853)		310		58		—		(366)		279		(6)		—		273
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

The amortized cost and fair value of fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  

(In thousands)	Amortized Cost (1)		Fair Value
Due in one year or less	$	1,818,820	$	1,742,384
Due after one year through five years	9,180,726		8,704,308
Due after five years through ten years	4,308,202		4,074,956
Due after ten years	2,609,192		2,436,157
Mortgage-backed securities	2,315,785		2,079,344
Total	$	20,232,725	$	19,037,149

________________

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(1) Amortized cost is reduced by the allowance for expected credit losses of $48 thousand related to held to maturity securities.    

At September 30, 2023 and December 31, 2022, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.

(7) Investments in Equity Securities

    At September 30, 2023 and December 31, 2022, investments in equity securities were as follows:

(In thousands)	Cost		Gross Unrealized				Fair Value		Carrying Value
			Gains		Losses
September 30, 2023
Common stocks	$	792,512	$	209,979	$	(41,058)	$	961,433	$	961,433
Preferred stocks	273,376		2,383		(55,131)		220,628		220,628
Total	$	1,065,888	$	212,362	$	(96,189)	$	1,182,061	$	1,182,061
December 31, 2022
Common stocks	$	855,987	$	192,165	$	(65,401)	$	982,751	$	982,751
Preferred stocks	259,341		1,053		(57,251)		203,143		203,143
Total	$	1,115,328	$	193,218	$	(122,652)	$	1,185,894	$	1,185,894

(8) Arbitrage Trading Account

    At September 30, 2023 and December 31, 2022, the fair and carrying values of the arbitrage trading account were $825 million and $944 million, respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less).

    The Company uses put options and call options in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options are reported at fair value. As of September 30, 2023, the fair value of long option contracts outstanding was $256 thousand (notional amount of $50 million) and the fair value of short option contracts was $6 million (notional amount of $50 million). Other than with respect to the use of these trading account securities, the Company does not make use of derivatives.

(9) Net Investment Income

    Net investment income consisted of the following: 

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Investment income (loss) earned on:
Fixed maturity securities, including cash and cash equivalents and loans receivable	$	239,727	$	146,051	$	653,200	$	371,724
Arbitrage trading account (1)	17,876		10,694		53,168		24,008
Equity securities	12,714		14,650		41,714		38,303
Investment funds	4,450		36,045		5,444		121,919
Real estate	(1,986)		(2,297)		(7,821)		(1,702)
Gross investment income	272,781		205,143		745,705		554,252
Investment expense	(1,837)		(2,327)		(6,211)		(6,350)
Net investment income	$	270,944	$	202,816	$	739,494	$	547,902

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(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.

(10) Investment Funds

    The Company evaluates whether it is an investor in a variable interest entity ("VIE"). Such entities do not have sufficient equity at risk to finance their activities without additional subordinated financial support, or the equity investors, as a group, do not have the characteristics of a controlling financial interest (primary beneficiary). The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE's capital structure, contractual terms, nature of the VIE's operations and purpose, and the Company's relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE and on an ongoing basis. The Company is not the primary beneficiary in any of its investment funds, and accordingly, carries its interests in investment funds under the equity method of accounting.    

    The Company’s maximum exposure to loss with respect to these investments is limited to the carrying amount reported on the Company’s consolidated balance sheet and its unfunded commitments, which were $353 million as of September 30, 2023.

    Investment funds consisted of the following:

	Carrying Value as of				Income (Loss) from Investment Funds
	September 30,		December 31,		For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Financial services	$	429,889	$	465,683	$	(15,606)	$	27,472
Transportation	336,020		336,753		37,894		48,249
Real Estate	191,445		204,644		(5,062)		42,708
Infrastructure	124,528		115,428		7,813		1,277
Energy	115,349		116,432		3,921		1,966
Other funds	403,264		369,608		(23,516)		247
Total	$	1,600,495	$	1,608,548	$	5,444	$	121,919

    The Company's share of the earnings or losses from investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

Financial services investment funds include the minority investment in Lifson Re, a Bermuda reinsurance company. Effective January 1, 2021, Lifson Re participated on a fully collateralized basis in a majority of the Company’s reinsurance placements for a 22.5% share of placed amounts. The percentage increased from 22.5% to 30% effective July 1, 2022. This pertains to all traditional reinsurance/retrocessional placements for both property and casualty business where there is more than one open market reinsurer participating. For the nine months ended September 30, 2023 and 2022, the Company ceded approximately $348 million and $308 million, respectively, of written premiums to Lifson Re.

Other funds include deferred compensation trust assets of $31 million and $30 million as of September 30, 2023 and December 31, 2022, respectively. These assets support other liabilities reflected in the balance sheet of an equal amount for employees who have elected to defer a portion of their compensation. The change in the net asset value of the trust is recorded in other funds within net investment income with an offsetting equal amount within corporate expenses.

(11) Real Estate

    Investment in real estate represents directly owned property held for investment, as follows:

	Carrying Value
	September 30,		December 31,
(In thousands)	2023		2022
Properties in operation	$	1,043,419	$	1,114,167
Properties under development	227,126		226,455
Total	$	1,270,545	$	1,340,622

    As of September 30, 2023, properties in operation included a long-term ground lease in Washington, D.C., an office complex in New York City and the completed portion of a mixed-use project in Washington D.C. Properties in operation are

14

net of accumulated depreciation and amortization of $31,039,000 and $33,206,000 as of September 30, 2023 and December 31, 2022, respectively. Related depreciation expense was $6,667,000 and $9,934,000 for the nine months ended September 30, 2023 and 2022, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $8,368,709 in 2023, $35,249,642 in 2024, $34,435,718 in 2025, $32,583,382 in 2026, $32,074,240 in 2027, $32,823,410 in 2028 and $505,344,609 thereafter.

The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

During the first quarter of 2022, the Company sold a real estate investment in London (proceeds from the real estate and related entity is presented on the business disposition line within the Consolidated Statements of Cash Flows).

    A mixed-use project in Washington, D.C. had been under development in 2023 and 2022, with the completed portion reported in properties in operation as of September 30, 2023.

(12) Loans Receivable

At September 30, 2023 and December 31, 2022, loans receivable were as follows:

(In thousands)	September 30, 2023		December 31, 2022
Amortized cost (net of allowance for expected credit losses):
Real estate loans	$	159,857	$	173,616
Commercial loans	17,893		19,386
Total	$	177,750	$	193,002
Fair value:
Real estate loans	$	156,407	$	168,595
Commercial loans	17,893		19,386
Total	$	174,300	$	187,981

The real estate loans are secured by commercial and residential real estate primarily located in London and New York. These loans generally earn interest at fixed or stepped interest rates and have maturities through 2026. The commercial loans are with small business owners who have secured the related financing with the assets of the business. Commercial loans primarily earn interest on a fixed basis and have varying maturities generally not exceeding 10 years.

Loans receivable in non-accrual status were none as of both September 30, 2023 and December 31, 2022, respectively.

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the nine months ended September 30, 2023 and 2022:

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	1,100	$	691	$	1,791	$	1,362	$	356	$	1,718
Change in expected credit losses	2,302		(84)		2,218		(200)		474		274
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses due to changes in economic assumptions utilized in its credit loss model. During the nine months ended September 30, 2022, the Company increased the allowance primarily due to an increase in the weighted average life of the loans receivable portfolio.

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended September 30, 2023 and 2022:

15

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	3,658	$	892	$	4,550	$	1,228	$	947	$	2,175
Change in expected credit losses	(256)		(285)		(541)		(66)		(117)		(183)
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

The Company monitors the performance of its loans receivable and assesses the ability of the borrower to pay principal and interest based upon loan structure, underlying property values, cash flow and related financial and operating performance of the property and market conditions.

    In evaluating the real estate loans, the Company considers their credit quality indicators, including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and performance with respect to loan terms, the position in the capital structure, the overall leverage in the capital structure and other market conditions.

16

(13) Net Investment (Losses) Gains

     Net investment (losses) gains were as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Net investment (losses) gains:
Fixed maturity securities:
Gains	$	299	$	1,053	$	1,357	$	3,405
Losses	(2,700)		(2,309)		(24,470)		(8,752)
Equity securities (1):
Net realized gains on investment sales (2)	23,631		—		135,763		946
Change in unrealized (losses) gains	(19,059)		(50,384)		45,605		(88,701)
Investment funds	(3,329)		(1,717)		(3,417)		(6,241)
Real estate (3) (4)	(24,234)		9,026		(68,944)		295,576
Loans receivable	(1,428)		—		(1,428)		(32)
Other	(14,035)		(21,951)		(34,063)		(56,537)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(40,855)		(66,282)		50,403		139,664
Change in allowance for expected credit losses on investments:
Fixed maturity securities	(2,112)		(1,311)		(8,946)		(12,091)
Loans receivable	541		183		(2,218)		(274)
Change in allowance for expected credit losses on investments	(1,571)		(1,128)		(11,164)		(12,365)
Net investment (losses) gains	(42,426)		(67,410)		39,239		127,299
Income tax benefit (expense)	9,405		14,456		(8,033)		(26,466)
After-tax net investment (losses) gains	$	(33,021)	$	(52,954)	$	31,206	$	100,833

Change in unrealized investment (losses) gains on available for sale securities:
Fixed maturity securities without allowance for expected credit losses	$	(136,388)	$	(385,503)	$	(57,293)	$	(1,335,413)
Fixed maturity securities with allowance for expected credit losses	(10,244)		(4,005)		(3,094)		(20,590)
Investment funds	(3,217)		(5,031)		(818)		(7,863)
Other	(606)		(293)		(1,271)		(1,198)
Total change in unrealized investment losses	(150,455)		(394,832)		(62,476)		(1,365,064)
Income tax benefit	32,090		79,168		11,626		288,847
Noncontrolling interests	—		—		(1)		(1)
After-tax change in unrealized investment losses of available for sale securities	$	(118,365)	$	(315,664)	$	(50,851)	$	(1,076,218)

______________________

(1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized (losses) gains consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held.

(2) In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million on the sale (proceeds from the sale is presented on the business disposition line within the Consolidated Statements of Cash Flows).

(3) The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

(4) During March 2022, the Company realized a gain on the sale of a real estate investment in London, U.K. of $251 million, net of transaction expenses and the foreign currency impact, including the reversal of the currency translation adjustment.

17

(14) Fixed Maturity Securities in an Unrealized Loss Position

    The following tables summarize all fixed maturity securities in an unrealized loss position at September 30, 2023 and December 31, 2022 by the length of time those securities have been continuously in an unrealized loss position:

	Less Than 12 Months				12 Months or Greater				Total
(In thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
September 30, 2023
U.S. government and government agency	$	605,944	$	17,390	$	592,215	$	64,377	$	1,198,159	$	81,767
State and municipal	645,642		15,255		1,728,892		167,938		2,374,534		183,193
Mortgage-backed	688,848		17,058		1,296,384		217,712		1,985,232		234,770
Asset-backed	1,025,656		8,774		2,584,224		100,251		3,609,880		109,025
Corporate	2,091,830		46,758		4,695,101		362,901		6,786,931		409,659
Foreign government	563,657		15,038		779,455		134,550		1,343,112		149,588
Fixed maturity securities	$	5,621,577	$	120,273	$	11,676,271	$	1,047,729	$	17,297,848	$	1,168,002
December 31, 2022
U.S. government and government agency	$	285,391	$	10,219	$	453,520	$	58,939	$	738,911	$	69,158
State and municipal	1,720,443		89,272		598,797		79,320		2,319,240		168,592
Mortgage-backed	1,099,549		75,430		473,318		115,528		1,572,867		190,958
Asset-backed	1,569,647		48,390		2,176,638		103,932		3,746,285		152,322
Corporate	3,690,856		150,115		2,349,281		256,631		6,040,137		406,746
Foreign government	477,672		29,815		711,786		105,243		1,189,458		135,058
Fixed maturity securities	$	8,843,558	$	403,241	$	6,763,340	$	719,593	$	15,606,898	$	1,122,834

    Substantially all of the securities in an unrealized loss position are rated investment grade, except for the securities in the foreign government classification. A significant amount of the unrealized loss on foreign government securities is the result of changes in currency exchange rates. 

    A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2023 is presented in the table below:

($ in thousands)	Number of Securities	Aggregate Fair Value		Gross Unrealized Loss
Foreign government	44	$	88,668	$	91,468
Corporate	26	35,644		3,523
State and municipal	5	22,866		6,374
Mortgage-backed	15	4,328		214
Asset-backed	5	244		107
Total	95	$	151,750	$	101,686

    For fixed maturity securities that management does not intend to sell or to be required to sell, the portion of the decline in value that is considered to be due to credit factors is recognized in earnings, and the portion of the decline in value that is considered to be due to non-credit factors is recognized in other comprehensive income (loss).

     The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due.

18

(15) Fair Value Measurements

    The Company’s fixed maturity available for sale securities, equity securities and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows:

Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable.

Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available.

    Substantially all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation.

    If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.

    For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate.

19

    The following tables present the assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 by level:

(In thousands)	Total		Level 1		Level 2		Level 3
September 30, 2023
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	1,467,199	$	—	$	1,467,199	$	—
State and municipal	2,670,998		—		2,670,998		—
Mortgage-backed	2,076,296		—		2,076,296		—
Asset-backed	4,087,458		—		4,087,458		—
Corporate	7,248,814		—		7,248,814		—
Foreign government	1,431,712		—		1,431,712		—
Total fixed maturity securities available for sale	18,982,477		—		18,982,477		—
Equity securities:
Common stocks	961,433		958,202		1,060		2,171
Preferred stocks	220,628		—		216,930		3,698
Total equity securities	1,182,061		958,202		217,990		5,869
Arbitrage trading account	825,049		614,995		206,536		3,518
Total	$	20,989,587	$	1,573,197	$	19,407,003	$	9,387
Liabilities:
Trading account securities sold but not yet purchased	$	7,538	$	7,538	$	—	$	—
December 31, 2022
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	892,258	$	—	$	892,258	$	—
State and municipal	2,890,098		—		2,890,098		—
Mortgage-backed	1,665,410		—		1,665,410		—
Asset-backed	3,982,773		—		3,982,773		—
Corporate	6,703,992		—		6,703,992		—
Foreign government	1,401,522		—		1,401,522		—
Total fixed maturity securities available for sale	17,536,053		—		17,536,053		—
Equity securities:
Common stocks	982,751		978,991		1,161		2,599
Preferred stocks	203,143		—		191,844		11,299
Total equity securities	1,185,894		978,991		193,005		13,898
Arbitrage trading account	944,230		822,192		118,448		3,590
Total	$	19,666,177	$	1,801,183	$	17,847,506	$	17,488
Liabilities:
Trading account securities sold but not yet purchased	$	—	$	—	$	—	$	—

20

    The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2023 and for the year ended December 31, 2022:

Gains (Losses) Included In:
(In thousands)	Beginning Balance		Earnings (Losses)		Other Comprehensive Income (Losses)		Impairments		Purchases		Sales		Paydowns / Maturities		Transfers In / (Out)		Ending Balance
Nine Months Ended September 30, 2023
Assets:
Equity securities:
Common stocks	$	2,599	$	(428)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,171
Preferred stocks	11,299		—		—		(7,601)		—		—		—		—		3,698
Total	13,898		(428)		—		(7,601)		—		—		—		—		5,869
Arbitrage trading account	3,590		(72)		—		—		—		—		—		—		3,518
Total	$	17,488	$	(500)	$	—	$	(7,601)	$	—	$	—	$	—	$	—	$	9,387
Year Ended December 31, 2022
Assets:
Equity securities:
Common stocks	$	9,294	$	(6,695)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,599
Preferred stocks	11,296		3		—		—		925		(925)		—		—		11,299
Total	20,590		(6,692)		—		—		925		(925)		—		—		13,898
Arbitrage trading account	—		(179)		—		—		4,686		(917)		—		—		3,590
Total	$	20,590	$	(6,871)	$	—	$	—	$	5,611	$	(1,842)	$	—	$	—	$	17,488

    For the nine months ended September 30, 2023 and for the year ended December 31, 2022, there were no securities transferred into or out of Level 3.

21

(16) Reserves for Loss and Loss Expenses

    The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities ("IBNR"). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims.

    Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit.

    The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions.

    The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns.

    Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations.

    Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags.

    The key assumptions used in calculating the most recent estimate of the loss reserves are reviewed each quarter and adjusted, to the extent necessary, to reflect the latest reported loss data, current trends and other factors observed.

22

    The table below provides a reconciliation of the beginning and ending reserve balances:

	September 30,
(In thousands)	2023		2022
Net reserves at beginning of period	$	14,248,879	$	12,848,362
Net provision for losses and loss expenses:
Claims occurring during the current year (1)	4,694,554		4,260,179
Increase in estimates for claims occurring in prior years (2) (3)	27,186		54,632
Loss reserve discount accretion	22,862		24,835
Total	4,744,602		4,339,646
Net payments for claims:
Current year	743,416		643,908
Prior years	2,915,979		2,499,319
Total	3,659,395		3,143,227
Foreign currency translation	(48,162)		(193,755)
Net reserves at end of period	15,285,924		13,851,026
Ceded reserves at end of period	2,987,386		2,689,097
Gross reserves at end of period	$	18,273,310	$	16,540,123

_______________________________________

(1) Claims occurring during the current year are net of loss reserve discounts of $35 million and $26 million for the nine months ended September 30, 2023 and 2022, respectively.

(2) The change in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $12 million and increased by $20 million for the nine months ended September 30, 2023 and 2022, respectively.

(3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Adverse development, net of additional and return premiums, was $20 million and $37 million for the nine months ended September 30, 2023 and 2022, respectively.

The COVID-19 global pandemic impacted, and may further impact, the Company’s loss costs. Accordingly, the ultimate net impact of COVID-19 on the Company’s reserves remains uncertain. As of September 30, 2023, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $354 million, of which $299 million relates to the Insurance segment and $55 million relates to the Reinsurance & Monoline Excess segment. Such $354 million of COVID-19-related losses are considered reported losses. For the nine months ended September 30, 2023, the Company recognized current accident year losses for COVID-19-related claims activity, net of reinsurance, of approximately $670 thousand, all of which relates to the Insurance segment.

During the nine months ended September 30, 2023, adverse prior year development (net of additional and return premiums) of $20 million included $26 million of adverse development for the Insurance segment, partially offset by $6 million of favorable development for the Reinsurance & Monoline Excess segment.

Such adverse development during the nine months ended September 30, 2023 was concentrated in the first quarter, with $24 million of adverse development (net of additional and return premiums) in the first quarter, partially offset by favorable development of $4 million in the second and third quarters. This overall adverse development during the first quarter in both business segments was due to property catastrophe losses related to 2022 events which were still being adjusted and settled. In particular, losses related to U.S. winter storms which occurred during the month of December were a significant driver of the development, as information gathering and evaluation of many of these losses was still ongoing into the new year.

For the Insurance segment, in addition to the property prior year adverse development discussed above, the adverse development during the nine months ended September 30, 2023 included adverse prior year development on casualty lines for the 2016 through 2019 accident years, which was largely offset by favorable prior year development on casualty lines for the 2020 through 2022 accident years. The adverse development on the 2016 through 2019 accident years was concentrated in the general liability line of business, and to a lesser degree professional liability, including medical professional, and commercial auto liability. The development, which particularly impacted business attaching excess of primary policy limits, was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

23

The favorable prior year development on casualty lines for the 2020 through 2022 accident years in the Insurance segment was concentrated in the professional liability, workers’ compensation, and general liability lines of business. Due to uncertainty regarding incurred loss frequency and severity in light of ongoing social inflation and the impacts of the COVID-19 pandemic, the Company set its initial loss ratios for the 2020 through 2022 accident years prudently, and largely maintained these estimates through the end of each respective accident year. The reported loss experience to date for these lines of business for the 2020 through 2022 accident years has been significantly better than was expected, and the Company has begun to react to this favorable emergence as the accident years mature beyond the age of 12 months. However, commercial auto liability experienced adverse prior year development for the 2020 through 2022 accident years, partially offsetting the favorable development discussed above, which was driven by a larger than expected number of large losses reported.

For the Reinsurance & Monoline Excess segment, the favorable development during the nine months ended September 30, 2023 was driven mainly by favorable development in excess workers’ compensation, partially offset by adverse development in property (discussed above) and non-proportional reinsurance assumed liability lines of business. The favorable excess workers’ compensation development was driven by continued lower claim frequency and reported losses relative to our expectations, and to favorable claim settlements. The favorable development was spread across many prior accident years. The adverse development on reinsurance assumed liability was associated primarily with our U.S. assumed reinsurance business, and related to accounts reinsuring excess and umbrella business and construction projects. The adverse development was concentrated mainly in accident years 2017 through 2020.

During the nine months ended September 30, 2022, adverse prior year development (net of additional and return premiums) of $37 million included $33 million for the Insurance segment and $4 million for the Reinsurance & Monoline Excess segment.

The adverse development for the Insurance segment primarily related to COVID-19 losses at two businesses. These businesses wrote policies providing coverage for event cancellation and film production delay which were heavily impacted by losses directly caused by the COVID-19 pandemic. Most of this COVID-19-related adverse development emerged during the third quarter as a result of settlements of claims at values higher than our expectations.

The adverse development mentioned above includes favorable prior year development for the Insurance segment primarily attributable to the 2020 and 2021 accident years and adverse development on the 2015 through 2019 accident years. The favorable development on the 2020 and 2021 accident years was concentrated in the other liability lines of business, including professional liability, products liability, commercial multi-peril liability and workers’ compensation. The Company experienced lower reported claim frequency in these lines of business during 2020 and 2021 relative to historical averages, and continues to experience lower reported incurred losses relative to our expectations for these accident years as they develop during 2022. These trends began in 2020 and we believe were caused by the impacts of the COVID-19 pandemic, including for example, lockdowns, reduced driving/traffic and increased work from home. Due to the ongoing uncertainty regarding the ultimate impacts of the pandemic on accident years 2020 and 2021 incurred losses, the Company has been cautious in reacting to these lower trends in setting and updating its loss ratio estimates for these years. As these accident years have continued to mature, the Company has continued to recognize some of the favorable reported experience in its ultimate loss estimates made during 2022.

The adverse development on the 2015 through 2019 accident years was concentrated in the other liability and professional liability, including medical professional, lines of business, as well as commercial auto liability. The development was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The overall slight adverse development for the Reinsurance & Monoline Excess segment was driven mainly by adverse development in the professional liability and non-proportional reinsurance assumed property and liability lines of business, substantially offset by favorable development in excess workers’ compensation. The adverse development was spread mainly across accident years 2015 through 2021 and was associated primarily with our U.S. assumed reinsurance business and related to accounts insuring construction projects and professional liability exposures. The favorable excess workers’ compensation development was mainly in 2011 and prior accident years, and was driven by a review of the Company’s claim reporting patterns as well as a number of favorable claim settlements relative to expectations.

24

(17) Fair Value of Financial Instruments

    The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:

	September 30, 2023				December 31, 2022
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Fixed maturity securities	$	19,035,305	$	19,037,149	$	17,587,349	$	17,591,626
Equity securities	1,182,061		1,182,061		1,185,894		1,185,894
Arbitrage trading account	825,049		825,049		944,230		944,230
Loans receivable	177,750		174,300		193,002		187,981
Cash and cash equivalents	1,646,074		1,646,074		1,449,346		1,449,346
Trading account receivables from brokers and clearing organizations	401,982		401,982		233,863		233,863
Due from broker	—		—		3,609		3,609
Liabilities:
Due to broker	5,118		5,118		—		—
Trading account securities sold but not yet purchased	7,538		7,538		—		—
Senior notes and other debt	1,828,046		1,321,014		1,828,823		1,439,188
Subordinated debentures	1,008,910		786,798		1,008,371		805,600

    The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

(18) Premiums and Reinsurance Related Information

The following is a summary of insurance and reinsurance financial information:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Written premiums:
Direct	$	3,037,932	$	2,775,236	$	8,762,249	$	8,075,311
Assumed	315,273		306,702		977,047		918,864
Ceded	(504,746)		(504,664)		(1,504,497)		(1,418,012)
Total net premiums written	$	2,848,459	$	2,577,274	$	8,234,799	$	7,576,163
Earned premiums:
Direct	$	2,825,176	$	2,617,680	$	8,217,888	$	7,533,856
Assumed	316,134		318,962		913,795		903,882
Ceded	(499,396)		(494,681)		(1,445,610)		(1,389,533)
Total net premiums earned	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205
Ceded losses and loss expenses incurred	$	320,995	$	347,439	$	970,267	$	905,667
Ceded commissions earned	$	118,207	$	121,721	$	354,148	$	356,157

    The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	30,660	$	25,218
Change in expected credit losses	2,942		5,360
Allowance for expected credit losses, end of period	$	33,602	$	30,578

25

The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	32,770	$	30,557
Change in expected credit losses	832		21
Allowance for expected credit losses, end of period	$	33,602	$	30,578

The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of an allowance for expected credit losses.

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	8,064	$	7,713
Change in expected credit losses	1,379		286
Allowance for expected credit losses, end of period	$	9,443	$	7,999

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	9,365	$	7,744
Change in expected credit losses	78		255
Allowance for expected credit losses, end of period	$	9,443	$	7,999

(19) Restricted Stock Units

    Pursuant to its stock incentive plan, the Company may issue restricted stock units ("RSUs") to employees of the Company and its subsidiaries. The RSUs generally vest three to five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $36 million and $34 million for the nine months ended September 30, 2023 and 2022, respectively. A summary of RSUs issued in the nine months ended September 30, 2023 and 2022 follows:

($ in thousands)	Units	Fair Value
2023	1,092,130	$	68,936
2022	1,023,871	$	67,345

(20) Litigation and Contingent Liabilities

    In the ordinary course of business, the Company is subject to disputes, litigation and arbitration arising from its insurance and reinsurance businesses. These matters are generally related to insurance and reinsurance claims and are considered in the establishment of loss and loss expense reserves. In addition, the Company may also become involved in legal actions which seek extra-contractual damages, punitive damages or penalties, including claims alleging bad faith in handling of insurance claims. The Company expects its ultimate liability with respect to such matters will not be material to its financial condition. However, adverse outcomes on such matters are possible, from time to time, and could be material to the Company’s results of operations in any particular financial reporting period.

26

(21) Leases

    Lessees are required to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months on the balance sheet. All leases disclosed within this footnote are classified as operating leases. Recognized right-of-use asset and lease liability are reported within other assets and other liabilities, respectively, in the consolidated balance sheet. Lease expense is reported in other operating costs and expenses in the consolidated statement of income and accounted for on a straight-line basis over the lease term.

    To determine the discount rate used to calculate present value of future minimum lease payments, the Company uses its incremental borrowing rate during the lease commencement period in line with the respective lease duration. In certain cases, the Company has the option to renew the lease. Lease renewal future payments are included in the present value of the future minimum lease payments when the Company determines it is reasonably certain to renew.

The main leases entered into by the Company are for office space used by the Company’s operating units across the world. Additionally, the Company, to a lesser extent, has equipment leases mainly for office equipment. Further information relating to operating lease expense and other operating lease information are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Leases:
Lease cost	$	10,122	$	11,299	$	30,448	$	33,649
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	$	11,403	$	11,082	$	33,247	$	33,128
Right-of-use assets obtained in exchange for new lease liabilities	$	6,543	$	1,527	$	14,489	$	21,729

	As of September 30,
($ in thousands)	2023			2022
Right-of-use assets	$	155,662		$	163,940
Lease liabilities	$	188,141		$	199,889
Weighted-average remaining lease term	6.9 years			7.1 years
Weighted-average discount rate	4.55		%	4.50		%

Contractual maturities of the Company’s future minimum lease payments are as follows:

(In thousands)	September 30, 2023
Contractual Maturities:
2023	$	12,171
2024	44,531
2025	36,167
2026	28,933
2027	19,144
Thereafter	74,394
Total undiscounted future minimum lease payments	215,340
Less: Discount impact	27,199
Total lease liability	$	188,141

27

(22) Business Segments

    The Company’s reportable segments include the following two business segments, plus a corporate segment:

•Insurance - predominantly commercial insurance business, including excess and surplus lines, admitted lines and specialty personal lines throughout the United States, as well as insurance business in Asia, Australia, Canada, Continental Europe, Mexico, Scandinavia, South America and the United Kingdom.

•Reinsurance & Monoline Excess - reinsurance business on a facultative and treaty basis, primarily in the United States, the United Kingdom, Continental Europe, Australia, the Asia-Pacific Region and South Africa, as well as operations that solely retain risk on an excess basis.

    The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Income tax expense and benefits are calculated based upon the Company's overall effective tax rate.

    Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment.

	Revenues
(In thousands)	Earned Premiums (1)		Investment Income		Other		Total (2)		Pre-Tax Income (Loss)		Net Income (Loss) to Common Stockholders
Three months ended September 30, 2023
Insurance	$	2,319,435	$	206,792	$	9,143	$	2,535,370	$	415,279	$	329,519
Reinsurance & Monoline Excess	322,479		56,259		—		378,738		106,072		83,314
Corporate, other and eliminations (3)	—		7,893		151,063		158,956		(58,976)		(46,226)
Net investment losses	—		—		(42,426)		(42,426)		(42,426)		(33,021)
Total	$	2,641,914	$	270,944	$	117,780	$	3,030,638	$	419,949	$	333,586
Three months ended September 30, 2022
Insurance	$	2,129,014	$	134,519	$	8,341	$	2,271,874	$	322,312	$	258,521
Reinsurance & Monoline Excess	312,947		55,234		—		368,181		59,561		46,875
Corporate, other and eliminations (3)	—		13,063		138,692		151,755		(28,198)		(23,563)
Net investment losses	—		—		(67,410)		(67,410)		(67,410)		(52,954)
Total	$	2,441,961	$	202,816	$	79,623	$	2,724,400	$	286,265	$	228,879
Nine months ended September 30, 2023
Insurance	$	6,747,704	$	560,182	$	27,570	$	7,335,456	$	1,153,742	$	903,575
Reinsurance & Monoline Excess	938,369		148,525		—		1,086,894		313,290		248,279
Corporate, other and eliminations (3)	—		30,787		429,180		459,967		(253,066)		(199,040)
Net investment gains	—		—		39,239		39,239		39,239		31,206
Total	$	7,686,073	$	739,494	$	495,989	$	8,921,556	$	1,253,205	$	984,020
Nine months ended September 30, 2022
Insurance	$	6,162,005	$	386,297	$	25,354	$	6,573,656	$	1,052,185	$	850,207
Reinsurance & Monoline Excess	886,200		139,768		—		1,025,968		209,366		167,329
Corporate, other and eliminations (3)	—		21,837		403,937		425,774		(147,590)		(119,530)
Net investment gains	—		—		127,299		127,299		127,299		100,833
Total	$	7,048,205	$	547,902	$	556,590	$	8,152,697	$	1,241,260	$	998,839

_________________

(1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions.

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(2) Revenues for Insurance from foreign operations for the three months ended September 30, 2023 and 2022 were $298 million and $252 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $852 million and $750 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended September 30, 2023 and 2022 were $124 million and $117 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $333 million and $307 million, respectively.

(3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments.

Identifiable Assets

(In thousands)	September 30, 2023		December 31, 2022
Insurance	$	28,862,050	$	27,012,479
Reinsurance & Monoline Excess	5,194,783		5,195,752
Corporate, other and eliminations	2,054,515		1,606,872
Consolidated	$	36,111,348	$	33,815,103

    Net premiums earned by major line of business are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Insurance:
Other liability	$	918,054	$	824,595	$	2,668,831	$	2,363,349
Short-tail lines (1)	490,598		407,211		1,383,654		1,184,191
Commercial automobile	335,572		307,754		965,416		891,729
Workers' compensation	300,694		307,323		905,405		892,390
Professional liability	274,517		282,131		824,398		830,346
Total Insurance	2,319,435		2,129,014		6,747,704		6,162,005
Reinsurance & Monoline Excess:
Casualty reinsurance	192,071		193,726		574,660		568,507
Monoline excess (2)	60,363		54,675		177,853		161,181
Property reinsurance	70,045		64,546		185,856		156,512
Total Reinsurance & Monoline Excess	322,479		312,947		938,369		886,200
Total	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205

______________

(1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

(2) Monoline excess includes operations that solely retain risk on an excess basis.

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SAFE HARBOR STATEMENT

    This is a “Safe Harbor” Statement under the Private Securities Litigation Reform Act of 1995. Any forward-looking statements contained herein, including statements related to our outlook for the industry and for our performance for the year 2023 and beyond, are based upon the Company’s historical performance and on current plans, estimates and expectations. The inclusion of this forward-looking information should not be regarded as a representation by us or any other person that the future plans, estimates or expectations contemplated by us will be achieved. They are subject to various risks and uncertainties, including but not limited to: the cyclical nature of the property casualty industry; the impact of significant competition, including new entrants to the industry; the long-tail and potentially volatile nature of the insurance and reinsurance business; product demand and pricing; claims development and the process of estimating reserves; investment risks, including those of our portfolio of fixed maturity securities and investments in equity securities, including investments in financial institutions, municipal bonds, mortgage-backed securities, loans receivable, investment funds, including real estate, merger arbitrage, energy related and private equity investments; the effects of emerging claim and coverage issues; the uncertain nature of damage theories and loss amounts, including claims for cybersecurity-related risks; natural and man-made catastrophic losses, including as a result of terrorist activities; the ongoing effects of the COVID-19 pandemic, or other epidemics and pandemics; the impact of climate change, which may alter the frequency and increase the severity of catastrophe events; general economic and market activities, including inflation, changing interest rates, and volatility in the credit and capital markets; the impact of the conditions in the financial markets and the global economy, and the potential effect of legislative, regulatory, accounting or other initiatives taken in response, on our results and financial condition; foreign currency and political risks relating to our international operations; our ability to attract and retain key personnel and qualified employees; continued availability of capital and financing; the success of our new ventures or acquisitions and the availability of other opportunities; the availability of reinsurance; our retention under the Terrorism Risk Insurance Program Reauthorization Act of 2019; the ability or willingness of our reinsurers to pay reinsurance recoverables owed to us; other legislative and regulatory developments, including those related to business practices in the insurance industry; credit risk related to our policyholders, independent agents and brokers; changes in the ratings assigned to us or our insurance company subsidiaries by rating agencies; the availability of dividends from our insurance company subsidiaries; cyber security breaches of our information technology systems and the information technology systems of our vendors and other third parties, or related processes and systems; the effectiveness of our controls to ensure compliance with guidelines, policies and legal and regulatory standards; and other risks detailed from time to time in the Company’s filings with the Securities and Exchange Commission.

    These risks and uncertainties could cause our actual results for the year 2023 and beyond to differ materially from those expressed in any forward-looking statement we make. Any projections of growth in our revenues would not necessarily result in commensurate levels of earnings. Our future financial performance is dependent upon factors discussed in our Annual Report on Form 10-K, elsewhere in this Form 10-Q and our other SEC filings. Forward-looking statements speak only as of the date on which they are made. Except to the extent required by applicable laws, the Company does not undertake any obligation to update or revise any forward-looking statement, whether as a result of new information, future developments or otherwise.

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Item 2.     Management’s Discussion and Analysis of Financial Condition and Results of Operations

Overview

    W. R. Berkley Corporation is an insurance holding company that is among the largest commercial lines writers in the United States and operates worldwide in two segments of the property and casualty business: Insurance and Reinsurance & Monoline Excess. Our decentralized structure provides us with the flexibility to respond quickly and efficiently to local or specific market conditions and to pursue specialty business niches. It also allows us to be closer to our customers in order to better understand their individual needs and risk characteristics. While providing our business units with certain operating autonomy, our structure allows us to capitalize on the benefits of economies of scale through centralized capital, investment, reinsurance, enterprise risk management, and actuarial, financial and corporate legal staff support. The Company’s primary sources of revenues and earnings are its insurance operations and its investments.

    An important part of our strategy is to form new operating units to capitalize on various business opportunities. Over the years, the Company has formed numerous operating units that are focused on important parts of the economy in the U.S., including healthcare, cyber security, energy and agriculture, and on growing international markets, including the Asia-Pacific region, South America and Mexico.

    The profitability of the Company’s insurance business is affected primarily by the adequacy of premium rates. The ultimate adequacy of premium rates is not known with certainty at the time an insurance policy is issued because premiums are determined before claims are reported. The ultimate adequacy of premium rates is affected mainly by the severity and frequency of claims, which are influenced by many factors, including natural and other disasters, regulatory measures and court decisions that define and change the extent of coverage and the effects of economic inflation on the amount of compensation for injuries or losses. General insurance prices are also influenced by available insurance capacity, i.e., the level of capital employed in the industry, and the industry’s willingness to deploy that capital.

    The Company’s profitability is also affected by its investment income and investment gains. The Company’s invested assets are invested principally in fixed maturity securities. The return on fixed maturity securities is affected primarily by general interest rates, as well as the credit quality and duration of the securities.

    The Company also invests in equity securities, merger arbitrage securities, investment funds, private equity, loans and real estate-related assets. The Company's investments in investment funds and its other alternative investments have experienced, and the Company expects to continue to experience, greater fluctuations in investment income. The Company's share of the earnings or losses from investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million.

On March 7, 2022, the Company sold a real estate investment consisting of an office building located in London for £718 million. The Company realized a pre-tax gain of $317 million in the first quarter of 2022, before transaction expenses and the impact of foreign currency, including the reversal of the currency translation adjustment. The gain was $251 million after such adjustments.

The ultimate impact of COVID-19 on the economy and the Company’s results of operations, financial position and liquidity is not within the Company’s control and remains unclear due to, among other factors, its ongoing impact and uncertainty in connection with its claims, reserves and reinsurance recoverables.

Critical Accounting Estimates

    The following presents a discussion of accounting policies and estimates relating to reserves for losses and loss expenses, assumed premiums and allowance for expected credit losses on investments. Management believes these policies and estimates are the most critical to its operations and require the most difficult, subjective and complex judgments.

    Reserves for Losses and Loss Expenses. To recognize liabilities for unpaid losses, either known or unknown, insurers establish reserves, which is a balance sheet account representing estimates of future amounts needed to pay claims and related expenses with respect to insured events which have occurred. Estimates and assumptions relating to reserves for losses and loss expenses are based on complex and subjective judgments, often including the interplay of specific uncertainties with related accounting and actuarial measurements. Such estimates are also susceptible to change as significant periods of time may

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elapse between the occurrence of an insured loss, the report of the loss to the insurer, the ultimate determination of the cost of the loss and the insurer’s payment of that loss.

    In general, when a claim is reported, claims personnel establish a “case reserve” for the estimated amount of the ultimate payment based upon known information about the claim at that time. The estimate represents an informed judgment based on general reserving practices and reflects the experience and knowledge of the claims personnel regarding the nature and value of the specific type of claim. Reserves are also established on an aggregate basis to provide for losses incurred but not reported (“IBNR”) to the insurer, potential inadequacy of case reserves and the estimated expenses of settling claims, including legal and other fees and general expenses of administrating the claims adjustment process. Reserves are established based upon the then current legal interpretation of coverage provided.

    In examining reserve adequacy, several factors are considered in estimating the ultimate economic value of losses. These factors include, among other things, historical data, legal developments, changes in social attitudes and economic conditions, including the effects of inflation. The actuarial process relies on the basic assumption that past experience, adjusted judgmentally for the effects of current developments and anticipated trends, is an appropriate basis for predicting future outcomes. Reserve amounts are based on management’s informed estimates and judgments using currently available data. As additional experience and other data become available and are reviewed, these estimates and judgments may be revised. This may result in reserve increases or decreases that would be reflected in our results in periods in which such estimates and assumptions are changed.

    Reserves do not represent an exact calculation of liability. Rather, reserves represent an estimate of what management expects the ultimate settlement and claim administration will cost. While the methods for establishing reserves are well tested over time, some of the major assumptions about anticipated loss emergence patterns are subject to uncertainty. These estimates, which generally involve actuarial projections, are based on management’s assessment of facts and circumstances then known, as well as estimates of trends in claims severity and frequency, judicial theories of liability and other factors, including the actions of third parties which are beyond the Company’s control. These variables are affected by external and internal events, such as inflation and economic volatility, judicial and litigation trends, reinsurance coverage, legislative changes and claim handling and reserving practices, which make it more difficult to accurately predict claim costs. The inherent uncertainties of estimating reserves are greater for certain types of liabilities where long periods of time elapse before a definitive determination of liability is made. Because setting reserves is inherently uncertain, the Company cannot provide assurance that its current reserves will prove adequate in light of subsequent events.

    Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. For example, the paid loss and incurred loss development methods rely on historical paid and incurred loss data. For new lines of business, where there is insufficient history of paid and incurred claims data, or in circumstances where there have been significant changes in claim practices, the paid and incurred loss development methods would be less credible than other actuarial methods. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” and in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit.

    The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions. Examples of changes in terms and conditions that can have a significant impact on reserve levels are the use of aggregate policy limits, the expansion of coverage exclusions, whether or not defense costs are within policy limits, and changes in deductibles and attachment points.

    The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current

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reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns. Management believes the estimates and assumptions it makes in the reserving process provide the best estimate of the ultimate cost of settling claims and related expenses with respect to insured events which have occurred; however, different assumptions and variables could lead to significantly different reserve estimates.

    Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations.

    Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags.

    The key assumptions used in calculating the most recent estimate of the loss reserves are reviewed each quarter and adjusted, to the extent necessary, to reflect the latest reported loss data, current trends and other factors observed. If the actual level of loss frequency and severity are higher or lower than expected, the ultimate losses will be different than management’s estimate. The following table reflects the impact of changes (which could be favorable or unfavorable) in frequency and severity, relative to our assumptions, on our loss estimate for claims occurring in 2022:

(In thousands)	Frequency (+/-)
Severity (+/-)	1%		5%		10%
1%	$	116,072	$	349,370	$	640,993
5%	349,370		591,908		895,081
10%	640,993		895,081		1,212,690

    Our net reserves for losses and loss expenses of approximately $15.3 billion as of September 30, 2023 relate to multiple accident years. Therefore, the impact of changes in frequency or severity for more than one accident year could be higher or lower than the amounts reflected above. The impact of such changes would likely be manifested gradually over the course of many years, as the magnitude of the changes became evident.

    Approximately $3.1 billion, or 20%, of the Company’s net loss reserves as of September 30, 2023 relate to the Reinsurance & Monoline Excess segment. There is a higher degree of uncertainty and greater variability regarding estimates of excess workers' compensation and assumed reinsurance loss reserves. In the case of excess workers’ compensation, our policies generally attach at $1 million or higher. The claims which reach our layer therefore tend to involve the most serious injuries and many remain open for the lifetime of the claimant, which extends the claim settlement tail. These claims also occur less frequently but tend to be larger than primary claims, which increases claim variability. In the case of assumed reinsurance our loss reserve estimates are based, in part, upon information received from ceding companies. If information received from ceding companies is not timely or correct, the Company’s estimate of ultimate losses may not be accurate. Furthermore, due to delayed reporting of claim information by ceding companies, the claim settlement tail for assumed reinsurance is also extended. Management considers the impact of delayed reporting and the extended tail in its selection of loss development factors for these lines of business.

    Information received from ceding companies is used to set initial expected loss ratios, to establish case reserves and to estimate reserves for incurred but not reported losses on assumed reinsurance business. This information, which is generally provided through reinsurance intermediaries, is gathered through the underwriting process and from periodic claim reports and other correspondence with ceding companies. The Company performs underwriting and claim audits of selected ceding

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companies to determine the accuracy and completeness of information provided to the Company. The information received from the ceding companies is supplemented by the Company’s own loss development experience with similar lines of business as well as industry loss trends and loss development benchmarks.

    Following is a summary of the Company’s reserves for losses and loss expenses by business segment:

(In thousands)	September 30, 2023		December 31, 2022
Insurance	$	12,205,280	$	11,233,924
Reinsurance & Monoline Excess	3,080,644		3,014,955
Net reserves for losses and loss expenses	15,285,924		14,248,879
Ceded reserves for losses and loss expenses	2,987,386		2,762,344
Gross reserves for losses and loss expenses	$	18,273,310	$	17,011,223

    Following is a summary of the Company’s net reserves for losses and loss expenses by major line of business:

(In thousands)	Reported Case Reserves		Incurred But Not Reported		Total
September 30, 2023
Other liability	$	1,862,458	$	4,371,078	$	6,233,536
Workers’ compensation (1)	1,020,327		819,013		1,839,340
Professional liability	526,656		1,397,442		1,924,098
Commercial automobile	694,854		681,336		1,376,190
Short-tail lines (2)	388,558		443,558		832,116
Total Insurance	4,492,853		7,712,427		12,205,280
Reinsurance & Monoline Excess (1) (3)	1,549,878		1,530,766		3,080,644
Total	$	6,042,731	$	9,243,193	$	15,285,924
December 31, 2022
Other liability	$	1,808,700	$	3,826,444	$	5,635,144
Workers’ compensation (1)	1,023,961		899,215		1,923,176
Professional liability	501,572		1,243,604		1,745,176
Commercial automobile	629,149		528,398		1,157,547
Short-tail lines (2)	403,974		368,907		772,881
Total Insurance	4,367,356		6,866,568		11,233,924
Reinsurance & Monoline Excess (1) (3)	1,551,687		1,463,268		3,014,955
Total	$	5,919,043	$	8,329,836	$	14,248,879

___________

(1) Reserves for workers’ compensation and Reinsurance & Monoline Excess are net of an aggregate net discount of $390 million and $416 million as of September 30, 2023 and December 31, 2022, respectively.

(2) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

(3) Reinsurance & Monoline Excess includes property and casualty reinsurance, as well as operations that solely retain risk on an excess basis.

    The Company evaluates reserves for losses and loss adjustment expenses on a quarterly basis. Changes in estimates of prior year losses are reported when such changes are made. The changes in prior year loss reserve estimates are generally the result of ongoing analysis of recent loss development trends. Original estimates are increased or decreased as additional information becomes known regarding individual claims and aggregate claim trends.

    Certain of the Company's insurance and reinsurance contracts are retrospectively rated, whereby the Company collects more or less premiums based on the level of loss activity. For those contracts, changes in loss and loss adjustment expenses for prior years may be fully or partially offset by additional or return premiums.

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    Net prior year development (i.e., the sum of prior year reserve changes and prior year earned premiums changes) for the nine months ended September 30, 2023 and 2022 are as follows:

(In thousands)	2023		2022
Increase in prior year loss reserves	$	(27,186)	$	(54,632)
Increase in prior year earned premiums	7,291		17,953
Net unfavorable prior year development	$	(19,895)	$	(36,679)

The COVID-19 global pandemic impacted, and may further impact, the Company’s loss costs. Accordingly, the ultimate net impact of COVID-19 on the Company’s reserves remains uncertain. As of September 30, 2023, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $354 million, of which $299 million relates to the Insurance segment and $55 million relates to the Reinsurance & Monoline Excess segment. Such $354 million of COVID-19-related losses are considered reported losses. For the nine months ended September 30, 2023, the Company recognized current accident year losses for COVID-19-related claims activity, net of reinsurance, of approximately $670 thousand, all of which relates to the Insurance segment.

During the nine months ended September 30, 2023, adverse prior year development (net of additional and return premiums) of $20 million included $26 million of adverse development for the Insurance segment, partially offset by $6 million of favorable development for the Reinsurance & Monoline Excess segment.

Such adverse development during the nine months ended September 30, 2023 was concentrated in the first quarter, with $24 million of adverse development (net of additional and return premiums) in the first quarter, partially offset by favorable development of $4 million in the second and third quarters. This overall adverse development during the first quarter in both business segments was due to property catastrophe losses related to 2022 events which were still being adjusted and settled. In particular, losses related to U.S. winter storms which occurred during the month of December were a significant driver of the development, as information gathering and evaluation of many of these losses was still ongoing into the new year.

For the Insurance segment, in addition to the property prior year adverse development discussed above, the adverse development during the nine months ended September 30, 2023 included adverse prior year development on casualty lines for the 2016 through 2019 accident years, which was largely offset by favorable prior year development on casualty lines for the 2020 through 2022 accident years. The adverse development on the 2016 through 2019 accident years was concentrated in the general liability line of business, and to a lesser degree professional liability, including medical professional, and commercial auto liability. The development, which particularly impacted business attaching excess of primary policy limits, was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The favorable prior year development on casualty lines for the 2020 through 2022 accident years in the Insurance segment was concentrated in the professional liability, workers’ compensation, and general liability lines of business. Due to uncertainty regarding incurred loss frequency and severity in light of ongoing social inflation and the impacts of the COVID-19 pandemic, the Company set its initial loss ratios for the 2020 through 2022 accident years prudently, and largely maintained these estimates through the end of each respective accident year. The reported loss experience to date for these lines of business for the 2020 through 2022 accident years has been significantly better than was expected, and the Company has begun to react to this favorable emergence as the accident years mature beyond the age of 12 months. However, commercial auto liability experienced adverse prior year development for the 2020 through 2022 accident years, partially offsetting the favorable development discussed above, which was driven by a larger than expected number of large losses reported.

For the Reinsurance & Monoline Excess segment, the favorable development during the nine months ended September 30, 2023 was driven mainly by favorable development in excess workers’ compensation, partially offset by adverse development in property (discussed above) and non-proportional reinsurance assumed liability lines of business. The favorable excess workers’ compensation development was driven by continued lower claim frequency and reported losses relative to our expectations, and to favorable claim settlements. The favorable development was spread across many prior accident years. The adverse development on reinsurance assumed liability was associated primarily with our U.S. assumed reinsurance business, and related to accounts reinsuring excess and umbrella business and construction projects. The adverse development was concentrated mainly in accident years 2017 through 2020.

During the nine months ended September 30, 2022, adverse prior year development (net of additional and return premiums) of $37 million included $33 million for the Insurance segment and $4 million for the Reinsurance & Monoline Excess segment.

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The adverse development for the Insurance segment primarily related to COVID-19 losses at two businesses. These businesses wrote policies providing coverage for event cancellation and film production delay which were heavily impacted by losses directly caused by the COVID-19 pandemic. Most of this COVID-19-related adverse development emerged during the third quarter as a result of settlements of claims at values higher than our expectations.

The adverse development mentioned above includes favorable prior year development for the Insurance segment primarily attributable to the 2020 and 2021 accident years and adverse development on the 2015 through 2019 accident years. The favorable development on the 2020 and 2021 accident years was concentrated in the other liability lines of business, including professional liability, products liability, commercial multi-peril liability and workers’ compensation. The Company experienced lower reported claim frequency in these lines of business during 2020 and 2021 relative to historical averages, and continues to experience lower reported incurred losses relative to our expectations for these accident years as they develop during 2022. These trends began in 2020 and we believe were caused by the impacts of the COVID-19 pandemic, including for example, lockdowns, reduced driving/traffic and increased work from home. Due to the ongoing uncertainty regarding the ultimate impacts of the pandemic on accident years 2020 and 2021 incurred losses, the Company has been cautious in reacting to these lower trends in setting and updating its loss ratio estimates for these years. As these accident years have continued to mature, the Company has continued to recognize some of the favorable reported experience in its ultimate loss estimates made during 2022.

The adverse development on the 2015 through 2019 accident years was concentrated in the other liability and professional liability, including medical professional, lines of business, as well as commercial auto liability. The development was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The overall slight adverse development for the Reinsurance & Monoline Excess segment was driven mainly by adverse development in the professional liability and non-proportional reinsurance assumed property and liability lines of business, substantially offset by favorable development in excess workers’ compensation. The adverse development was spread mainly across accident years 2015 through 2021 and was associated primarily with our U.S. assumed reinsurance business and related to accounts insuring construction projects and professional liability exposures. The favorable excess workers’ compensation development was mainly in 2011 and prior accident years, and was driven by a review of the Company’s claim reporting patterns as well as a number of favorable claim settlements relative to expectations.

Reserve Discount. The Company discounts its liabilities for certain workers’ compensation reserves. The amount of workers’ compensation reserves that were discounted was $1,356 million and $1,464 million at September 30, 2023 and December 31, 2022, respectively. The aggregate net discount for those reserves, after reflecting the effects of ceded reinsurance, was $390 million and $416 million at September 30, 2023 and December 31, 2022, respectively. At September 30, 2023, discount rates by year ranged from 0.7% to 6.5%, with a weighted average discount rate of 3.4%.

    Substantially all of the workers’ compensation discount (97% of total discounted reserves at September 30, 2023) relates to excess workers’ compensation reserves. In order to properly match loss expenses with income earned on investment securities supporting the liabilities, reserves for excess workers’ compensation business are discounted using risk-free discount rates determined by reference to the U.S. Treasury yield curve. These rates are determined annually based on the weighted average rate for the period. Once established, no adjustments are made to the discount rate for that period, and any increases or decreases in loss reserves in subsequent years are discounted at the same rate, without regard to when any such adjustments are recognized. The expected loss and loss expense payout patterns subject to discounting are derived from the Company’s loss payout experience.

    The Company also discounts reserves for certain other long-duration workers’ compensation reserves (representing approximately 3% of total discounted reserves at September 30, 2023), including reserves for quota share reinsurance and reserves related to losses regarding occupational lung disease. These reserves are discounted at statutory rates permitted by the Department of Insurance of the State of Delaware.

    Assumed Reinsurance Premiums. The Company estimates the amount of assumed reinsurance premiums that it will receive under treaty reinsurance agreements at the inception of the contracts. These premium estimates are revised as the actual amount of assumed premiums is reported to the Company by the ceding companies. As estimates of assumed premiums are made or revised, the related amount of earned premiums, commissions and incurred losses associated with those premiums are recorded. Estimated assumed premiums receivable were approximately $58 million at September 30, 2023 and $60 million at December 31, 2022. The assumed premium estimates are based upon terms set forth in reinsurance agreements, information received from ceding companies during the underwriting and negotiation of agreements, reports received from ceding companies and discussions and correspondence with reinsurance intermediaries. The Company also considers its own view of

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market conditions, economic trends and experience with similar lines of business. These premium estimates represent management’s best estimate of the ultimate amount of premiums to be received under its assumed reinsurance agreements.

    Allowance for Expected Credit Losses on Investments.

    Fixed Maturity Securities – For fixed maturity securities in an unrealized loss position where the Company intends to sell, or it is more likely than not that it will be required to sell the security before recovery in value, the amortized cost basis is written down to fair value through net investment gains (losses). For fixed maturity securities in an unrealized loss position where the Company does not intend to sell, or it is more likely than not that it will not be required to sell the security before recovery in value, the Company evaluates whether the decline in fair value has resulted from credit losses or all other factors (non-credit factors). In making this assessment, the Company considers the extent to which fair value is less than amortized cost, changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, an allowance for expected credit losses is recorded for the credit loss through net investment gains (losses), limited by the amount that the fair value is less than the amortized cost basis. The allowance is adjusted for any change in expected credit losses and subsequent recoveries through net investment gains (losses). The impairment related to non-credit factors is recognized in other comprehensive income (loss).

    The Company’s credit assessment of allowance for expected credit losses uses a third party model for available for sale and held to maturity securities, as well as loans receivable. The allowance for expected credit losses is generally based on the performance of the underlying collateral under various economic and default scenarios that involve subjective judgments and estimates by management. Modeling these securities involves various factors, such as projected default rates, the nature and realizable value of the collateral, if any, the ability of the issuer to make scheduled payments, historical performance and other relevant economic and performance factors. A discounted cash flow analysis is used to ascertain the amount of the allowance for expected credit losses, if any. In general, the model reverts to the rating-level long-term average marginal default rates based on 10 years of historical data, beyond the forecast period. For other inputs, the model in most cases reverts to the baseline long-term assumptions linearly over 5 years beyond the forecast period. The long-term assumptions are based on the historical averages.

    The Company classifies its fixed maturity securities by credit rating, primarily based on ratings assigned by credit rating agencies. For purposes of classifying securities with different ratings, the Company uses the average of the credit ratings assigned, unless in limited situations the Company’s own analysis indicates an internal rating is more appropriate. Securities that are not rated by a rating agency are evaluated and classified by the Company on a case-by-case basis.

    A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2023 is presented in the table below:

($ in thousands)	Number of Securities	Aggregate Fair Value		Gross Unrealized Loss
Foreign government	44	$	88,668	$	91,468
Corporate	26	35,644		3,523
State and municipal	5	22,866		6,374
Mortgage-backed	15	4,328		214
Asset-backed	5	244		107
Total	95	$	151,750	$	101,686

    As of September 30, 2023, the Company has recorded an allowance for expected credit losses on fixed maturity securities of $46 million. The Company has evaluated the remaining fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due.

Loans Receivable – For loans receivable, the Company estimates an allowance for expected credit losses based on relevant information about past events, including historical loss experience, current conditions and forecasts that affect the expected collectability of the amortized cost of the financial asset. The allowance for expected credit losses is presented as a reduction to amortized cost of the financial asset in the consolidated balance sheet and changes to the estimate for expected credit losses are recognized through net investment gains (losses). Loans receivable are reported net of an allowance for expected credit losses of $4 million and $2 million as of September 30, 2023 and December 31, 2022, respectively.

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    Fair Value Measurements. The Company’s fixed maturity available for sale securities, equity securities, and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for similar assets in active markets. Level 3 inputs are unobservable inputs for the asset or liability. Unobservable inputs may only be used to measure fair value to the extent that observable inputs are not available. The fair value of the vast majority of the Company’s portfolio is based on observable data (other than quoted prices) and, accordingly, is classified as Level 2.

    In classifying particular financial securities in the fair value hierarchy, the Company uses its judgment to determine whether the market for a security is active and whether significant pricing inputs are observable. The Company determines the existence of an active market by assessing whether transactions occur with sufficient frequency and volume to provide reliable pricing information. The Company determines whether inputs are observable based on the use of such information by pricing services and external investment managers, the uninterrupted availability of such inputs, the need to make significant adjustments to such inputs and the volatility of such inputs over time. If the market for a security is determined to be inactive or if significant inputs used to price a security are determined to be unobservable, the security is categorized in Level 3 of the fair value hierarchy.

    Because many fixed maturity securities do not trade on a daily basis, the Company utilizes pricing models and processes which may include benchmark curves, benchmarking of like securities, sector groupings and matrix pricing. Market inputs used to evaluate securities include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data. Quoted prices are often unavailable for recently issued securities that are infrequently traded or securities that are only traded in private transactions. For publicly traded securities for which quoted prices are unavailable, the Company determines fair value based on independent broker quotations and other observable market data. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial data, projections and business developments of the issuer and other relevant information.

    The following is a summary of pricing sources for the Company's fixed maturity securities available for sale as of September 30, 2023:

($ in thousands)	Carrying Value		Percent of Total
Pricing source:
Independent pricing services	$	18,502,851	97.5	%
Syndicate manager	75,978		0.4
Directly by the Company based on:
Observable data	403,648		2.1
Total	$	18,982,477	100.0	%

    Independent pricing services – Substantially all of the Company’s fixed maturity securities available for sale were priced by independent pricing services (generally one U.S. pricing service plus additional pricing services with respect to a limited number of foreign securities held by the Company). The prices provided by the independent pricing services are generally based on observable market data in active markets (e.g., broker quotes and prices observed for comparable securities). The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness based upon current trading levels for similar securities. If the prices appear unusual to the Company, they are re-examined and the value is either confirmed or revised. In addition, the Company periodically performs independent price tests of a sample of securities to ensure proper valuation and to verify our understanding of how securities are priced. As of September 30, 2023, the Company did not make any adjustments to the prices provided by the pricing services. Based upon the Company’s review of the methodologies used by the independent pricing services, these securities were classified as Level 2.

    Syndicate manager – The Company has a 15% participation in a Lloyd’s syndicate, and the Company’s share of the securities owned by the syndicate is priced by the syndicate’s manager. The majority of the securities are liquid, short duration fixed maturity securities. The Company reviews the syndicate manager’s pricing methodology and audited financial statements and holds discussions with the syndicate manager as necessary to confirm its understanding and agreement with security prices.

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Based upon the Company’s review of the methodologies used by the syndicate manager, these securities were classified as Level 2.

    Observable data – If independent pricing is not available, the Company prices the securities directly. Prices are based on observable market data where available, including current trading levels for similar securities and non-binding quotations from brokers. The Company generally requests two or more quotes. If more than one quote is received, the Company sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes obtained from brokers. Since these securities were priced based on observable data, they were classified as Level 2.

    Cash flow model – If the above methodologies are not available, the Company prices securities using a discounted cash flow model based upon assumptions as to prevailing credit spreads, interest rates and interest rate volatility, time to maturity and subordination levels. Discount rates are adjusted to reflect illiquidity where appropriate. These securities were classified as Level 3.

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Results of Operations for the Nine Months Ended September 30, 2023 and 2022

Business Segment Results

Following is a summary of gross and net premiums written, net premiums earned, loss ratios (losses and loss expenses incurred expressed as a percentage of net premiums earned), expense ratios (underwriting expenses expressed as a percentage of net premiums earned) and GAAP combined ratios (sum of loss ratio and expense ratio) for each of our business segments for the nine months ended September 30, 2023 and 2022. The GAAP combined ratio represents a measure of underwriting profitability, excluding investment income. A GAAP combined ratio in excess of 100 indicates an underwriting loss; a number below 100 indicates an underwriting profit.

($ in thousands)	2023			2022
Insurance:
Gross premiums written	$	8,659,128		$	7,976,288
Net premiums written	7,246,773			6,637,024
Net premiums earned	6,747,704			6,162,005
Loss ratio	62.8		%	61.3		%
Expense ratio	28.4		%	27.9		%
GAAP combined ratio	91.2		%	89.2		%
Reinsurance & Monoline Excess:
Gross premiums written	$	1,080,168		$	1,017,887
Net premiums written	988,026			939,139
Net premiums earned	938,369			886,200
Loss ratio	53.7		%	63.7		%
Expense ratio	28.7		%	28.4		%
GAAP combined ratio	82.4		%	92.1		%
Consolidated:
Gross premiums written	$	9,739,296		$	8,994,175
Net premiums written	8,234,799			7,576,163
Net premiums earned	7,686,073			7,048,205
Loss ratio	61.7		%	61.6		%
Expense ratio	28.4		%	28.0		%
GAAP combined ratio	90.1		%	89.6		%

    Net Income to Common Stockholders. The following table presents the Company’s net income to common stockholders and net income per diluted share for the nine months ended September 30, 2023 and 2022:

(In thousands, except per share data)	2023		2022
Net income to common stockholders	$	984,020	$	998,839
Weighted average diluted shares	274,146		279,644
Net income per diluted share	$	3.59	$	3.57

    The Company reported net income to common stockholders of $984 million in 2023 compared to $999 million in 2022. The $15 million reduction in net income was primarily due to an after-tax reduction in net investment gains of $69 million mainly due to the gain on sale of a real estate investment in 2022, an after-tax decrease in foreign currency gains of $66 million mainly due to lower strengthening of the U.S. dollar against other currencies in 2023, an increase of $27 million in tax expense due to a change in the effective tax rate, an after-tax increase in corporate expenses of $23 million primarily due to increased compensation-related costs and an after-tax decrease in profits from non-insurance businesses of $5 million, partially offset by an after-tax increase in net investment income of $151 million primarily due to rising interest rates and a larger investment portfolio of fixed maturity securities, an after-tax increase in underwriting income of $19 million, an after-tax reduction in minority interest of $3 million and an after-tax reduction in interest expense of $2 million due to debt repayments in 2022. The number of weighted average diluted shares decreased by 5.5 million for 2023 compared to 2022, mainly reflecting shares repurchased in 2023.

    Premiums. Gross premiums written were $9,739 million in 2023, an increase of 8% from $8,994 million in 2022. The increase was due to a $683 million increase in the Insurance segment and a $62 million increase in the Reinsurance & Monoline

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Excess segment. Approximately 80% of premiums expiring in 2023 were renewed, and 82% of premiums expiring in 2022 were renewed.

    Average renewal premium rates for insurance and facultative reinsurance increased 7.2% in 2023 when adjusted for changes in exposures, and increased 8.3% excluding workers' compensation.

    A summary of gross premiums written in 2023 compared with 2022 by line of business within each business segment follows:

•Insurance - gross premiums increased 9% to $8,659 million in 2023 from $7,976 million in 2022. Gross premiums increased $360 million (12%) for other liability, $325 million (18%) for short-tail lines, $101 million (10%) for commercial automobile and $1 million (less than 1%) for workers' compensation, partially offset by a reduction of $104 million (8%) for professional liability.

•Reinsurance & Monoline Excess - gross premiums increased 6% to $1,080 million in 2023 from $1,018 million in 2022. Gross premiums increased $54 million (28%) for property reinsurance and $22 million (10%) for monoline excess, partially offset by a reduction of $14 million (2%) for casualty reinsurance.

    Net premiums written were $8,235 million in 2023, an increase of 9% from $7,576 million in 2022. Ceded reinsurance premiums as a percentage of gross written premiums were 15% in 2023 and 16% in 2022.

    Premiums earned increased 9% to $7,686 million in 2023 from $7,048 million in 2022. Insurance premiums (including the impact of rate changes) are generally earned evenly over the policy term, and accordingly, recent rate increases will be earned over the upcoming quarters. Premiums earned in 2023 are related to business written during both 2023 and 2022. Audit premiums were $271 million in 2023 compared with $219 million in 2022 due to an increase in exposures.

    Net Investment Income. Following is a summary of net investment income for the nine months ended September 30, 2023 and 2022:

	Amount				Average Annualized Yield
($ in thousands)	2023		2022		2023		2022
Fixed maturity securities, including cash and cash equivalents and loans receivable	$	653,200	$	371,724	4.2	%	2.6	%
Arbitrage trading account	53,168		24,008		5.9		2.8
Equity securities	41,714		38,303		5.0		4.9
Investment funds	5,444		121,919		0.5		10.1
Real estate	(7,821)		(1,702)		(0.8)		(0.2)
Gross investment income	745,705		554,252		3.8		3.1
Investment expenses	(6,211)		(6,350)		—		—
Total	$	739,494	$	547,902	3.8	%	3.0	%

    Net investment income increased 35% to $739 million in 2023 from $548 million in 2022 due primarily to an $282 million increase in income from fixed maturity securities mainly driven by rising interest rates and a larger investment portfolio, a $29 million increase from the arbitrage trading account (including investment income from trading account receivables from brokers and clearing organizations) and a $3 million increase from equity securities, partially offset by a $117 million decrease in income from investment funds primarily due to financial services and real estate funds and a $6 million decrease in real estate. The Company maintained the shortened duration of its fixed maturity security portfolio, thereby reducing the potential impact of mark-to-market on the portfolio and positioning the Company to react quickly to changes in the current interest rate environment. We expect investment income to increase as we reinvest our fixed maturity portfolio at the current higher rates. Average invested assets, at cost (including cash and cash equivalents), were $26.1 billion in 2023 up 8.1% from $24.2 billion in 2022.

    Insurance Service Fees. The Company earns fees from an insurance distribution business (part of which was sold in June 2023), a third-party administrator and as a servicing carrier of workers' compensation assigned risk plans for certain states. Insurance service fees were $81 million in 2023 and $82 million in 2022.

    Net Realized and Unrealized Gains on Investments. The Company buys and sells securities and other investment assets on a regular basis in order to maximize its total return on investments. Decisions to sell securities and other investment assets are based on management’s view of the underlying fundamentals of specific investments as well as management’s expectations

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regarding interest rates, credit spreads, currency values and general economic conditions. Net realized and unrealized gains on investments were $50 million in 2023 compared with $140 million in 2022. The gains of $50 million in 2023 reflected net realized gains on investments of $5 million (primarily a pre-tax net realized gain of $88 million on the sale of the property

and casualty insurance services division of Breckenridge IS, Inc., partially offset by the impairment of $72 million recognized on the real estate investments) and an increase in unrealized gains on equity securities of $45 million. The gains of $140 million in 2022 reflected net realized gains on investments of $228 million (primarily a $251 million net gain from the sale of a real estate investment in London after transaction expenses and the foreign currency impact, including the reversal of the currency translation adjustment) partially offset by an increase in unrealized losses on equity securities of $89 million.

Change in Allowance for Expected Credit Losses on Investments. Based on credit factors, the allowance for expected credit losses is increased or decreased depending on the percentage of unrealized loss relative to amortized cost by security, changes in rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. The pre-tax change in allowance for expected credit losses on investments increased by $11 million ($9 million after-tax) and $12 million ($10 million after-tax) in 2023 and 2022, respectively, which are both reflected in net investment gains (losses), primarily due to change in estimate.

Revenues from Non-Insurance Businesses. Revenues from non-insurance businesses were derived from businesses engaged in the distribution of promotional merchandise, world-wide textile solutions and aviation-related businesses that provide services to aviation markets, including (i) the distribution, manufacturing, repair and overhaul of aircraft parts and components, (ii) the sale of new and used aircraft, and (iii) avionics, fuel, maintenance, storage and charter services. Revenues from non-insurance businesses were $375 million in 2023 and $345 million in 2022. The increase mainly relates to aviation-related business and the commercial and residential textile business, which we acquired in 2022, partially offset by the decrease of promotional merchandise and existing textile business.

    Losses and Loss Expenses. Losses and loss expenses increased to $4,745 million in 2023 from $4,340 million in 2022. The consolidated loss ratio was 61.7% in 2023 and 61.6% in 2022. Catastrophe losses, net of reinsurance recoveries, were $163 million (including current accident year losses of approximately $670 thousand related to COVID-19) in 2023 and $181 million (including losses of approximately $4 million related to COVID-19) in 2022. Adverse prior year reserve development (net of premium offsets) was $20 million in 2023 and $37 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development increased 0.9 points to 59.4% in 2023 from 58.5% in 2022.

    A summary of loss ratios in 2023 compared with 2022 by business segment follows:

•Insurance - The loss ratio was 62.8% in 2023 and 61.3% in 2022. Catastrophe losses were $139 million in 2023 compared with $102 million in 2022. Adverse prior year reserve development was $26 million in 2023, principally from property catastrophe losses, and $33 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development increased 1.3 points to 60.4% in 2023 from 59.1% in 2022.

•Reinsurance & Monoline Excess - The loss ratio was 53.7% in 2023 and 63.7% in 2022. Catastrophe losses were $24 million in 2023 compared with $79 million in 2022. Favorable prior year reserve development was $6 million in 2023, and adverse prior year reserve development was $4 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development decreased 2.4 points to 51.9% in 2023 from 54.3% in 2022.

Other Operating Costs and Expenses. Following is a summary of other operating costs and expenses for the nine months ended September 30, 2023 and 2022:

($ in thousands)	2023		2022
Policy acquisition and insurance operating expenses	$	2,183,517	$	1,974,676
Insurance service expenses	70,336		71,348
Net foreign currency gains	(1,777)		(85,060)
Other costs and expenses	205,849		178,292
Total	$	2,457,925	$	2,139,256

    Policy acquisition and insurance operating expenses are comprised of commissions paid to agents and brokers, premium taxes and other assessments and internal underwriting costs. Policy acquisition and insurance operating expenses increased 11% and net premiums earned increased 9% from 2022. The expense ratio (underwriting expenses expressed as a percentage of net premiums earned) increased by 0.4 points to 28.4% in 2023 from 28.0% in 2022 mainly due to lower ceding commissions, increased compensation costs and new start-up operating unit expenses.

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    Service expenses, which represent the costs associated with the fee-based businesses, were $70 million in 2023 and $71 million in 2022.

    Net foreign currency gains result from transactions denominated in a currency other than a company's operating functional currency. Net foreign currency gains were $2 million in 2023 compared to $85 million in 2022, primarily due to lower strengthening of the U.S. dollar against other currencies in 2023.

    Other costs and expenses represent general and administrative expenses of the parent company and other expenses not allocated to business segments, including the cost of certain long-term incentive plans and new business ventures. Other costs and expenses increased to $206 million in 2023 from $178 million in 2022, primarily due to the increase in compensation-related costs in 2023.

    Expenses from Non-Insurance Businesses. Expenses from non-insurance businesses represent costs associated with businesses engaged in the distribution of promotional merchandise, world-wide textile solutions and aviation-related businesses that include (i) cost of goods sold related to aircraft and products sold and services provided, and (ii) general and administrative expenses. Expenses from non-insurance businesses were $370 million in 2023 compared to $334 million in 2022. The increase mainly relates to the aviation-related business and the residential and commercial textile business, which we acquired in 2022, partially offset by the decrease of promotional merchandise and existing textile business.

Interest Expense. Interest expense was $96 million in 2023 and $98 million in 2022. In the first quarter of 2022, the Company repaid at maturity its $77 million aggregate principal amount of 8.7% senior notes in January and its $350 million aggregate principal amount of 4.625% senior notes in March.

Income Taxes. The effective income tax rate was 21.4% and 19.2% for the nine months ended September 30, 2023 and 2022, respectively. The higher effective income tax rate for the nine months ended September 30, 2023, as compared to the earlier period, was primarily due to a net reduction to the Company’s valuation allowance against foreign tax credits and foreign net operating losses in the earlier period.

    The Company has not provided U.S. deferred income taxes on the undistributed earnings of approximately $217 million of its non-U.S. subsidiaries since these earnings are intended to be permanently reinvested in the non-U.S. subsidiaries. In the future, if such earnings were distributed, the Company projects that the incremental tax, if any, will be immaterial.

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Results of Operations for the Three Months Ended September 30, 2023 and 2022

Business Segment Results

Following is a summary of gross and net premiums written, net premiums earned, loss ratios (losses and loss expenses incurred expressed as a percentage of net premiums earned), expense ratios (underwriting expenses expressed as a percentage of net premiums earned) and GAAP combined ratios (sum of loss ratio and expense ratio) for each of our business segments for the three months ended September 30, 2023 and 2022. The GAAP combined ratio represents a measure of underwriting profitability, excluding investment income. A GAAP combined ratio in excess of 100 indicates an underwriting loss; a number below 100 indicates an underwriting profit.

($ in thousands)	2023			2022
Insurance:
Gross premiums written	$	2,990,869		$	2,719,824
Net premiums written	2,508,740			2,237,608
Net premiums earned	2,319,435			2,129,014
Loss ratio	62.6		%	63.2		%
Expense ratio	28.4		%	28.0		%
GAAP combined ratio	91.0		%	91.2		%
Reinsurance & Monoline Excess:
Gross premiums written	$	362,336		$	362,114
Net premiums written	339,719			339,666
Net premiums earned	322,479			312,947
Loss ratio	56.8		%	70.2		%
Expense ratio	27.8		%	28.4		%
GAAP combined ratio	84.6		%	98.6		%
Consolidated:
Gross premiums written	$	3,353,205		$	3,081,938
Net premiums written	2,848,459			2,577,274
Net premiums earned	2,641,914			2,441,961
Loss ratio	61.9		%	64.1		%
Expense ratio	28.3		%	28.0		%
GAAP combined ratio	90.2		%	92.1		%

    Net Income to Common Stockholders. The following table presents the Company’s net income to common stockholders and net income per diluted share for the three months ended September 30, 2023 and 2022:

(In thousands, except per share data)	2023		2022
Net income to common stockholders	$	333,586	$	228,879
Weighted average diluted shares	271,439		279,642
Net income per diluted share	$	1.23	$	0.82

    The Company reported net income to common stockholders of $334 million in 2023 compared to $229 million in 2022. The $105 million increase in net income was primarily due to an after-tax increase in net investment income of $54 million primarily due to rising interest rates and a larger investment portfolio of fixed maturity securities, an after-tax increase in underwriting income of $53 million mainly due to the growth in premium rates, an after-tax decrease in net investment losses of $20 million mainly due to the change in market value on equity securities, and an after-tax reduction in minority interest of $2 million, partially offset by an after-tax decrease in foreign currency gains of $15 million mainly due to lower strengthening of the U.S. dollar against other currencies in 2023, an after-tax increase in corporate expenses of $5 million due to increased compensation-related costs, an increase of $3 million in tax expense due to a change in the effective tax rate and an after-tax decrease in profits from insurance service income of $1 million. The number of weighted average diluted shares decreased by 8.2 million for 2023 compared to 2022, mainly reflecting shares repurchased in 2023.

    Premiums. Gross premiums written were $3,353 million in 2023, an increase of 9% from $3,082 million in 2022. The increase was due to a $271 million increase in the Insurance segment and a $222 thousand increase in the Reinsurance & Monoline Excess segment. Approximately 80.5% of premiums expiring in 2023 were renewed, and 81% of premiums expiring in 2022 were renewed.

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    Average renewal premium rates for insurance and facultative reinsurance increased 7.2% in 2023 when adjusted for changes in exposures, and increased 8.5% excluding workers' compensation.

    A summary of gross premiums written in 2023 compared with 2022 by line of business within each business segment follows:

•Insurance - gross premiums increased 10% to $2,991 million in 2023 from $2,720 million in 2022. Gross premiums increased $135 million (13%) for other liability, $122 million (20%) for short-tail lines, and $58 million (16%) for commercial automobile, and decreased $40 million (9%) for professional liability and $4 million (1%) for workers' compensation.

•Reinsurance & Monoline Excess - gross premiums remained flat in 2023 with 2022 at $362 million. Gross premiums increased $9 million (11%) for property reinsurance and $9 million (12%) for monoline excess, and decreased $18 million (9%) for casualty reinsurance.

    Net premiums written were $2,848 million in 2023, an increase of 11% from $2,577 million in 2022. Ceded reinsurance premiums as a percentage of gross written premiums were 15% in 2023 and 16% in 2022.

    Premiums earned increased 8% to $2,642 million in 2023 from $2,442 million in 2022. Insurance premiums (including the impact of rate changes) are generally earned evenly over the policy term, and accordingly, recent rate increases will be earned over the upcoming quarters. Premiums earned in 2023 are related to business written during both 2023 and 2022. Audit premiums were $88 million in 2023 compared with $77 million in 2022 due to an increase in exposures.

    Net Investment Income. Following is a summary of net investment income for the three months ended September 30, 2023 and 2022:

	Amount				Average Annualized Yield
($ in thousands)	2023		2022		2023		2022
Fixed maturity securities, including cash and cash equivalents and loans receivable	$	239,727	$	146,051	4.5	%	3.0	%
Arbitrage trading account	17,876		10,694		5.9		3.7
Equity securities	12,714		14,650		4.7		5.1
Investment funds	4,450		36,045		1.1		8.5
Real estate	(1,986)		(2,297)		(0.6)		(0.7)
Gross investment income	272,781		205,143		4.1		3.3
Investment expenses	(1,837)		(2,327)		—		—
Total	$	270,944	$	202,816	4.1	%	3.3	%

    Net investment income increased 34% to $271 million in 2023 from $203 million in 2022 due primarily to a $94 million increase in income from fixed maturity securities mainly driven by rising interest rates and a larger investment portfolio, a $7 million increase from arbitrage trading account (including investment income from trading account receivables from brokers and clearing organizations) and a $1 million reduction from investment expenses, partially offset by a $32 million decrease in income from investment funds primarily due to real estate funds and transportation funds and a $2 million decrease from equity securities. The Company maintained the short duration of its fixed maturity security portfolio, thereby reducing the potential impact of mark-to-market on the portfolio and positioning the Company to react quickly to changes in the current interest rate environment. We expect investment income to increase as we reinvest our fixed maturity portfolio at the current higher rates. Average invested assets, at cost (including cash and cash equivalents), were $26.7 billion in 2023 and $24.6 billion in 2022.

    Insurance Service Fees. The Company earns fees from an insurance distribution business, a third-party administrator and as a servicing carrier of workers' compensation assigned risk plans for certain states. Insurance service fees were $23 million in 2023 and $28 million in 2022. The decrease in service fees resulted from the sale of the property and casualty insurance services division of Breckenridge IS, Inc.

    Net Realized and Unrealized Gains (Losses) on Investments. The Company buys and sells securities and other investment assets on a regular basis in order to maximize its total return on investments. Decisions to sell securities and other investment assets are based on management’s view of the underlying fundamentals of specific investments as well as management’s expectations regarding interest rates, credit spreads, currency values and general economic conditions. Net realized and unrealized losses on investments were $41 million in 2023 and $66 million in 2022. The losses of $41 million in

45

2023 reflected net realized losses on investments of $22 million (primarily due to an impairment of $21 million recognized on a real estate investment) and an increase in unrealized losses on equity securities of $19 million. The losses of $66 million in 2022 reflected net realized losses on investments of $16 million (primarily due to foreign exchange losses on investments) and an increase in unrealized losses on equity securities of $50 million.

Change in Allowance for Expected Credit Losses on Investments. Based on credit factors, the allowance for expected credit losses is increased or decreased depending on the percentage of unrealized loss relative to amortized cost by security, changes in rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. The pre-tax change in allowance for expected credit losses on investments increased by $2 million ($1 million after-tax) and $1 million ($0.9 million after-tax) in 2023 and 2022, respectively, which are reflected in net investment gains (losses), primarily due to change in estimate.

Revenues from Non-Insurance Businesses. Revenues from non-insurance businesses were derived from businesses engaged in the distribution of promotional merchandise, world-wide textile solutions and aviation-related businesses that provide services to aviation markets, including (i) the distribution, manufacturing, repair and overhaul of aircraft parts and components, (ii) the sale of new and used aircraft, and (iii) avionics, fuel, maintenance, storage and charter services. Revenues from non-insurance businesses increased to $137 million in 2023 from $119 million in 2022 mainly due to the aviation-related businesses.

    Losses and Loss Expenses. Losses and loss expenses increased to $1,636 million in 2023 from $1,565 million in 2022. The consolidated loss ratio was 61.9% in 2023 and 64.1% in 2022. Catastrophe losses, net of reinsurance recoveries, were $62 million (including current accident year losses of approximately $411 thousand related to COVID-19) in 2023 and $94 million (including losses of approximately $1 million related to COVID-19) in 2022. Favorable prior year reserve development (net of premium offsets) was $1 million in 2023 and adverse prior year reserve development was $39 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development increased 1.0 point to 59.6% in 2023 from 58.6% in 2022.

    A summary of loss ratios in 2023 compared with 2022 by business segment follows:

•Insurance - The loss ratio was 62.6% in 2023 and 63.2% in 2022. Catastrophe losses were $46 million in 2023 compared with $51 million in 2022. Adverse prior year reserve development was $1 million in 2023 and $35 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development increased 1.5 points to 60.6% in 2023 from 59.1% in 2022.

•Reinsurance & Monoline Excess - The loss ratio was 56.8% in 2023 and 70.2% in 2022. Catastrophe losses were $16 million in 2023 compared with $43 million in 2022. Favorable prior year reserve development was $2 million in 2023 and adverse prior year reserve development was $4 million in 2022. The loss ratio excluding catastrophe losses and prior year reserve development decreased 2.7 points to 52.6% in 2023 from 55.3% in 2022.

Other Operating Costs and Expenses. Following is a summary of other operating costs and expenses for the three months ended September 30, 2023 and 2022:

($ in thousands)	2023		2022
Policy acquisition and insurance operating expenses	$	747,007	$	685,325
Insurance service expenses	21,225		24,991
Net foreign currency gains	(22,498)		(41,065)
Other costs and expenses	62,935		56,286
Total	$	808,669	$	725,537

    Policy acquisition and insurance operating expenses are comprised of commissions paid to agents and brokers, premium taxes and other assessments and internal underwriting costs. Policy acquisition and insurance operating expenses increased 9% and net premiums earned increased 8% from 2022. The expense ratio (underwriting expenses expressed as a percentage of net premiums earned) increased by 0.3% to 28.3% in 2023 from 28.0% in 2022 mainly due to lower ceding commissions, increased compensation costs and new start-up operating unit expenses.

    Service expenses, which represent the costs associated with the fee-based businesses, were $21 million in 2023, down from $25 million in 2022, as a result of the sale of the property and casualty insurance services division of Breckenridge IS, Inc.

    Net foreign currency gains result from transactions denominated in a currency other than a company's operating functional currency. Net foreign currency gains were $22 million in 2023 compared to $41 million in 2022, primarily due to lower strengthening of the U.S. dollar against other currencies in 2023.

46

Other costs and expenses represent general and administrative expenses of the parent company and other expenses not allocated to business segments, including the cost of certain long-term incentive plans and new business ventures. Other costs and expenses increased to $63 million in 2023 from $56 million in 2022, primarily due to the increase in compensation-related costs in 2023.

    Expenses from Non-Insurance Businesses. Expenses from non-insurance businesses represent costs associated with businesses engaged in the distribution of promotional merchandise, world-wide textile solutions and aviation-related businesses that include (i) cost of goods sold related to aircraft and products sold and services provided, and (ii) general and administrative expenses. Expenses from non-insurance businesses increased to $134 million in 2023 from $116 million in 2022 mainly due to the aviation-related businesses.

Interest Expense. Interest expense was $32 million in both 2023 and 2022.

Income Taxes. The effective income tax rate was 20.6% and 19.5% for the three months ended September 30, 2023 and 2022, respectively. The effective income tax rate increased for the three months ended September 30, 2023, primarily due to a lower tax benefit related to equity-based compensation, as well as higher foreign and state income taxes.

    The Company has not provided U.S. deferred income taxes on the undistributed earnings of approximately $217 million of its non-U.S. subsidiaries since these earnings are intended to be permanently reinvested in the non-U.S. subsidiaries. In the future, if such earnings were distributed the Company projects that the incremental tax, if any, will be immaterial.

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Investments

    As part of its investment strategy, the Company establishes a level of cash and highly liquid short-term and intermediate-term securities that, combined with expected cash flow, it believes is adequate to meet its payment obligations. In addition to fixed maturity securities, the Company invests in equity securities, merger arbitrage securities, investment funds, private equity, loans and real estate related assets. The Company's investments in investment funds and its other alternative investments have experienced, and the Company expects to continue to experience, greater fluctuations in investment income.

    The Company also attempts to maintain an appropriate relationship between the average duration of the investment portfolio and the approximate duration of its liabilities (i.e., policy claims and debt obligations). The average duration of the fixed maturity portfolio, including cash and cash equivalents, was 2.4 years at both September 30, 2023 and December 31, 2022. The Company’s fixed maturity investment portfolio and investment-related assets as of September 30, 2023 were as follows:

($ in thousands)	Carrying Value		Percent of Total
Fixed maturity securities:
U.S. government and government agencies	$	1,467,199	5.6	%
State and municipal:
Special revenue	1,646,921		6.3
State general obligation	405,969		1.6
Local general obligation	385,340		1.5
Corporate backed	179,973		0.7
Pre-refunded (1)	102,594		0.3
Total state and municipal	2,720,797		10.4
Mortgage-backed:
Agency	1,250,357		4.8
Commercial	629,512		2.4
Residential-Prime	196,519		0.8
Residential-Alt A	2,937		—
Total mortgage-backed	2,079,325		8.0
Asset-backed	4,087,458		15.6
Corporate:
Industrial	3,344,567		12.8
Financial	2,679,247		10.3
Utilities	643,277		2.5
Other	581,723		2.2
Total corporate	7,248,814		27.8
Foreign government and foreign government agencies	1,431,712		5.5
Total fixed maturity securities	19,035,305		72.9
Equity securities:
Common stocks	961,433		3.7
Preferred stocks	220,628		0.8
Total equity securities	1,182,061		4.5
Cash and cash equivalents (2)	2,035,399		7.8
Investment funds	1,600,495		6.1
Real estate	1,270,545		4.9
Arbitrage trading account	825,049		3.1
Loans receivable	177,750		0.7
Total investments	$	26,126,604	100.0	%

____________________

(1) Pre-refunded securities are securities for which an escrow account has been established to fund the remaining payments of principal and interest through maturity. Such escrow accounts are funded almost exclusively with U.S. Treasury and U.S. government agency securities.

(2) Cash and cash equivalents includes trading accounts receivable from brokers and clearing organizations, trading account securities sold but not yet purchased and unsettled purchases.

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Fixed Maturity Securities. The Company’s investment policy with respect to fixed maturity securities is generally to purchase instruments with the expectation of holding them to their maturity. However, management of the available for sale portfolio is considered necessary to maintain an approximate matching of assets and liabilities as well as to adjust the portfolio as a result of changes in financial market conditions and tax considerations.

The Company’s philosophy related to holding or selling fixed maturity securities is based on its objective of maximizing total return. The key factors that management considers in its investment decisions as to whether to hold or sell fixed maturity securities are its view of the underlying fundamentals of specific securities as well as its expectations regarding interest rates, credit spreads and currency values. In a period in which management expects interest rates to rise, the Company may sell longer duration securities in order to mitigate the impact of an interest rate rise on the fair value of the portfolio. Similarly, in a period in which management expects credit spreads to widen, the Company may sell lower quality securities, and in a period in which management expects certain foreign currencies to decline in value, the Company may sell securities denominated in those foreign currencies. The sale of fixed maturity securities in order to achieve the objective of maximizing total return may result in realized gains or losses; however, there is no reason to expect these gains or losses to continue in future periods.

Equity Securities. Equity securities primarily represent investments in common and preferred stocks in companies with potential growth opportunities in different sectors, mainly in the financial institutions, energy and technology sectors.

Investment Funds. At September 30, 2023, the carrying value of investment funds was $1.6 billion, including investments in financial services funds of $430 million, other funds of $403 million (which includes a deferred compensation trust asset of $31 million), transportation funds of $336 million, real estate funds of $191 million, infrastructure funds of $125 million and energy funds of $115 million. Investment funds are generally reported on a one-quarter lag.

Real Estate. Real estate is directly owned property held for investment. At September 30, 2023, real estate properties in operation included a long-term ground lease in Washington D.C., an office complex in New York City and the completed portion of a mixed-use project in Washington D.C. In addition, part of the previously mentioned mixed-use project in Washington D.C. is under development. The Company expects to fund further development costs for the project with a combination of its own funds and external financing. The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively. During the first quarter of 2022, the Company sold an office building in London.

Arbitrage Trading Account. The arbitrage trading account is comprised of direct investments in arbitrage securities. Merger arbitrage is the business of investing in the securities of publicly held companies that are the targets in announced tender offers and mergers.

Loans Receivable. Loans receivable, which are carried at amortized cost (net of allowance for expected credit losses), had an amortized cost of $178 million and an aggregate fair value of $174 million at September 30, 2023. The amortized cost of loans receivable is net of an allowance for expected credit losses of $4 million as of September 30, 2023. Loans receivable include real estate loans of $160 million that are secured by commercial and residential real estate located primarily in London and New York. Real estate loans generally earn interest at fixed or stepped interest rates and have maturities through 2026. Loans receivable include commercial loans of $18 million that are secured by business assets and have fixed interest rates with varying maturities not exceeding 10 years.

Market Risk. The fair value of the Company’s investments is subject to risks of fluctuations in credit quality and interest rates. The Company uses various models and stress test scenarios to monitor and manage interest rate risk. The Company attempts to manage its interest rate risk by maintaining an appropriate relationship between the effective duration of the investment portfolio and the approximate duration of its liabilities (i.e., policy claims and debt obligations). The effective duration for the fixed maturity portfolio (including cash and cash equivalents) was 2.4 years at both September 30, 2023 and December 31, 2022.

In addition, the fair value of the Company’s international investments is subject to currency risk. The Company attempts to manage its currency risk by matching its foreign currency assets and liabilities where considered appropriate.

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Liquidity and Capital Resources

    Cash Flow. Cash flow provided from operating activities increased to $2,231 million in the nine months ended September 30, 2023 from $1,773 million in the nine months ended September 30, 2022, primarily due to increased premium receipts, partially offset by an increase in loss and loss expense payments.

    The Company's insurance subsidiaries' principal sources of cash are premiums, investment income, service fees and proceeds from sales and maturities of portfolio investments. The principal uses of cash are payments for claims, taxes, operating expenses and dividends. The Company expects its insurance subsidiaries to fund the payment of losses with cash received from premiums, investment income and fees. The Company generally targets an average duration for its investment portfolio that is within 1.5 years of the average duration of its liabilities so that portions of its investment portfolio mature throughout the claim cycle and are available for the payment of claims if necessary. In the event operating cash flow and proceeds from maturities and prepayments of fixed income securities are not sufficient to fund claim payments and other cash requirements, the remainder of the Company's cash and investments is available to pay claims and other obligations as they become due. The Company's investment portfolio is highly liquid, with approximately 80% invested in cash, cash equivalents and marketable fixed maturity securities as of September 30, 2023. If the sale of fixed maturity securities were to become necessary, a realized gain or loss equal to the difference between the cost and sales price of securities sold would be recognized.

    Debt. At September 30, 2023, the Company had senior notes, subordinated debentures and other debt outstanding with a carrying value of $2,837 million and a face amount of $2,865 million. In the first quarter of 2022, the Company repaid at maturity its $77 million aggregate principal amount of 8.7% senior notes in January and its $350 million aggregate principal amount of 4.625% senior notes in March. The maturities of the outstanding debt are $7 million in 2024, $3 million in 2025, $250 million in 2037, $350 million in 2044, $470 million in 2050, $400 million in 2052, $185 million in 2058, $300 million in 2059, $250 million in 2060, and $650 million in 2061.

On April 1, 2022, the Company entered into a senior unsecured revolving credit facility that provides for revolving, unsecured borrowings up to an aggregate of $300 million with a $50 million sublimit for letters of credit. The Company may increase the amount available under the facility to a maximum of $500 million subject to obtaining lender commitments for the increase and other customary conditions. Borrowings under the facility may be used for working capital and other general corporate purposes. All borrowings under the facility must be repaid by April 1, 2027, except that letters of credit outstanding on that date may remain outstanding until April 1, 2028 (or such later date approved by all lenders). Our ability to utilize the facility is conditioned on the satisfaction of representations, warranties and covenants that are customary for facilities of this type. As of September 30, 2023, there were no borrowings outstanding under the facility.

    Equity. At September 30, 2023, total common stockholders’ equity was $6.9 billion, common shares outstanding were 258,043,531 and stockholders’ equity per outstanding share was $26.80. During the nine months ended September 30, 2023, the Company repurchased 7,146,975 shares of its common stock for $430.5 million. In the third quarter of 2023, the board of directors of the Company declared a regular quarterly cash dividend of $0.11 per share and a special cash dividend of $0.50 per share. In the second quarter of 2023, the board of directors of the Company declared a regular quarterly cash dividend of $0.11 per share. In the first quarter of 2023, the board of directors of the Company declared a regular quarterly cash dividend of $0.10 per share and a special cash dividend of $0.50 per share. The number of common shares outstanding excludes shares held in a grantor trust established by the Company for delivery upon settlement of vested but mandatorily deferred RSUs.

    Total Capital. Total capitalization (equity, debt and subordinated debentures) was $9.8 billion at September 30, 2023. The percentage of the Company’s capital attributable to senior notes, subordinated debentures and other debt was 29% at September 30, 2023 and 30% at December 31, 2022.

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Item 3.     Quantitative and Qualitative Disclosure About Market Risk

    Reference is made to the information under “Investments - Market Risk” under the caption “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in this Form 10-Q.

Item 4.     Controls and Procedures

    Disclosure Controls and Procedures. The Company’s management, including its Chief Executive Officer and Chief Financial Officer, has conducted an evaluation of the effectiveness of the Company’s disclosure controls and procedures pursuant to Securities Exchange Act Rule 13a-14 as of the end of the period covered by this quarterly report. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that the Company has in place effective controls and procedures designed to ensure that information required to be disclosed by the Company in the reports it files or submits under the Securities Exchange Act of 1934, as amended, and the rules thereunder, is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission’s rules and forms.

    Changes in Internal Control over Financial Reporting. During the quarter ended September 30, 2023, there were no changes in the Company’s internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

PART II — OTHER INFORMATION

Item 1. Legal Proceedings

    Please see Note 20 to the notes to the interim consolidated financial statements.

Item 1A. Risk Factors

There have been no material changes from the risk factors previously disclosed in the Company’s annual report on Form 10-K for the fiscal year ended December 31, 2022.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds    

    Set forth below is a summary of the shares repurchased by the Company during the three months ended September 30, 2023, and the number of shares remaining authorized for purchase by the Company:

	Total number of shares purchased	Average price paid per share		Total number of shares purchased as part of publicly announced plans or programs	Maximum number of shares that may yet be purchased under the plans or programs
July 2023	—	$	—	—	14,850,000
August 2023	48,016	$	60.75	48,016	14,801,984
September 2023	—	$	—	—	14,801,984

Item 5. Other Information

None of the Company's directors or officers adopted, modified or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement during the quarter ended September 30, 2023, as such terms are defined under Item 408(a) of Regulation S-K.

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Item 6. Exhibits

Number
(31.1)	Certification of the Chief Executive Officer pursuant to Rule 13a-14(a)/ 15d-14(a).
(31.2)	Certification of the Chief Financial Officer pursuant to Rule 13a-14(a)/ 15d-14(a).
(32.1)	Certification of the Chief Executive Officer and Chief Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned thereunto duly authorized.

		W. R. BERKLEY CORPORATION
Date:	November 3, 2023	/s/ W. Robert Berkley, Jr.
		W. Robert Berkley, Jr.
		President and Chief Executive Officer
Date:	November 3, 2023	/s/ Richard M. Baio
		Richard M. Baio
		Executive Vice President - Chief Financial Officer

53

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, W. Robert Berkley, Jr., President and Chief Executive Officer of W. R. Berkley Corporation (the “registrant”), certify that:

1. I have reviewed this quarterly report on Form 10-Q of the registrant;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ W. Robert Berkley, Jr.

W. Robert Berkley, Jr.

President and
Chief Executive Officer 

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, Richard M. Baio, Senior Vice President - Chief Financial Officer and Treasurer of W. R. Berkley Corporation (the “registrant”), certify that:

1. I have reviewed this quarterly report on Form 10-Q of the registrant;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Richard M. Baio

Richard M. Baio

Executive Vice President,
Chief Financial Officer and Treasurer

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of W. R. Berkley Corporation (the “Company”) on Form 10-Q for the period ended September 30, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), we, W. Robert Berkley, Jr., President and Chief Executive Officer of the Company, and Richard M. Baio, Senior Vice President - Chief Financial Officer and Treasurer of the Company, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that:

(1)The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ W. Robert Berkley, Jr.

W. Robert Berkley, Jr.

President and Chief Executive Officer

/s/ Richard M. Baio

Richard M. Baio

Executive Vice President,
Chief Financial Officer and Treasurer

November 3, 2023

A signed original of this written statement required by Section 906 has been provided to W. R. Berkley Corporation (the “Company”) and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.

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Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 30, 2023
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	1-15202
Entity Registrant Name	W. R. BERKLEY CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-1867895
Entity Address, Address Line One	475 Steamboat Road
Entity Address, City or Town	Greenwich
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06830
City Area Code	(203)
Local Phone Number	629-3000
Title of 12(b) Security	Common Stock, par value $.20 per share
Trading Symbol	WRB
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		257,872,034
Entity Central Index Key	0000011544
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
5.700% Subordinated Debentures due 2058
Entity Information [Line Items]
Title of 12(b) Security	5.700% Subordinated Debentures due 2058
Trading Symbol	WRB-PE
Security Exchange Name	NYSE
5.100% Subordinated Debentures due 2059
Entity Information [Line Items]
Title of 12(b) Security	5.100% Subordinated Debentures due 2059
Trading Symbol	WRB-PF
Security Exchange Name	NYSE
4.250% Subordinated Debentures due 2060
Entity Information [Line Items]
Title of 12(b) Security	4.250% Subordinated Debentures due 2060
Trading Symbol	WRB-PG
Security Exchange Name	NYSE
4.125% Subordinated Debentures due 2061
Entity Information [Line Items]
Title of 12(b) Security	4.125% Subordinated Debentures due 2061
Trading Symbol	WRB-PH
Security Exchange Name	NYSE

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Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Investments:
Fixed maturity securities (amortized cost of $20,232,773 and $18,715,483; allowance for expected credit losses of $46,412 and $37,466 at September 30, 2023 and December 31, 2022, respectively)	$ 19,035,305	$ 17,587,349
Investment funds	1,600,495	1,608,548
Real estate	1,270,545	1,340,622
Equity securities	1,182,061	1,185,894
Arbitrage trading account	825,049	944,230
Loans receivable (net of allowance for expected credit losses of $4,009 and $1,791 at September 30, 2023 and December 31, 2022, respectively)	177,750	193,002
Total investments	24,091,205	22,859,645
Cash and cash equivalents	1,646,074	1,449,346
Premiums and fees receivable (net of allowance for expected credit losses of $33,602 and $30,660 at September 30, 2023 and December 31, 2022, respectively)	3,104,609	2,779,244
Due from reinsurers (net of allowance for expected credit losses of $9,443 and $8,064 at September 30, 2023 and December 31, 2022, respectively)	3,426,196	3,187,730
Deferred policy acquisition costs	854,374	763,486
Prepaid reinsurance premiums	756,236	696,468
Trading account receivables from brokers and clearing organizations	401,982	233,863
Property, furniture and equipment	423,279	423,232
Goodwill	174,597	185,509
Accrued investment income	201,206	166,784
Current and deferred federal and foreign income taxes	291,363	333,774
Other assets	740,227	736,022
Total assets	36,111,348	33,815,103
Liabilities:
Reserves for losses and loss expenses	18,273,310	17,011,223
Unearned premiums	5,899,738	5,297,654
Due to reinsurers	626,448	523,131
Trading account securities sold but not yet purchased	7,538	0
Other liabilities	1,537,449	1,377,740
Senior notes and other debt	1,828,046	1,828,823
Subordinated debentures	1,008,910	1,008,371
Total liabilities	29,181,439	27,046,942
Equity:
Perferred stock, par value $.10 per share: Authorized 5,000,000 shares; issued and outstanding - none	0	0
Common stock, par value $.20 per share: Authorized 500,000,000 shares, issued and outstanding, net of treasury shares, 177,930,502 and 183,411,907 shares, respectively	105,803	105,803
Additional paid-in capital	1,008,301	997,534
Retained earnings	10,800,697	10,161,005
Accumulated other comprehensive loss	(1,322,819)	(1,264,581)
Treasury stock, at cost, 270,971,091 and 264,468,528 shares, respectively	(3,676,403)	(3,251,429)
Total stockholders’ equity	6,915,579	6,748,332
Noncontrolling interests	14,330	19,829
Total equity	6,929,909	6,768,161
Total liabilities and equity	$ 36,111,348	$ 33,815,103

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Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 20,232,773	$ 18,715,483
Fixed maturity securities, allowance for credit loss	46,412	37,466
Cumulative effect adjustment resulting from changes in accounting principles	4,009	1,791
Cumulative effect adjustment resulting from changes in accounting principles	33,602	30,660
Reinsurance recoverable, allowance for credit loss	$ 9,443	$ 8,064
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock issued (in shares)	5,000,000	5,000,000
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollar per share)	$ 0.20	$ 0.20
Common shares authorized (in shares)		1,250,000,000
Common shares issued (in shares)	258,043,531	264,546,100
Common shares outstanding (in shares)	258,043,531	264,546,100
Treasury stock issued at cost (in shares)	270,971,091	264,468,528

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Consolidated Statements Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
REVENUES:
Net premiums written	$ 2,848,459	$ 2,577,274	$ 8,234,799	$ 7,576,163
Change in net unearned premiums	(206,545)	(135,313)	(548,726)	(527,958)
Net premiums earned	2,641,914	2,441,961	7,686,073	7,048,205
Net investment income	270,944	202,816	739,494	547,902
Net realized and unrealized (losses) gains on investments	(40,855)	(66,282)	50,403	139,664
Change in allowance for expected credit losses on investments	(1,571)	(1,128)	(11,164)	(12,365)
Net investment (losses) gains	(42,426)	(67,410)	39,239	127,299
Revenues from non-insurance businesses	137,116	119,013	375,225	345,210
Insurance service fees	22,962	27,940	81,290	82,284
Other income	128	80	235	1,797
Total revenues	3,030,638	2,724,400	8,921,556	8,152,697
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,636,193	1,564,578	4,744,602	4,339,646
Other operating costs and expenses	808,669	725,537	2,457,925	2,139,256
Expenses from non-insurance businesses	133,939	116,240	370,244	334,062
Interest expense	31,888	31,780	95,580	98,473
Total operating costs and expenses	2,610,689	2,438,135	7,668,351	6,911,437
Income before income taxes	419,949	286,265	1,253,205	1,241,260
Income tax expense	(86,519)	(55,791)	(268,322)	(238,290)
Net income before noncontrolling interests	333,430	230,474	984,883	1,002,970
Noncontrolling interests	156	(1,595)	(863)	(4,131)
Net income to common stockholders	$ 333,586	$ 228,879	$ 984,020	$ 998,839
NET INCOME PER SHARE:
Basic (in dollar per share)	$ 1.24	$ 0.83	$ 3.62	$ 3.61
Diluted (in dollar per share)	$ 1.23	$ 0.82	$ 3.59	$ 3.57

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Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 333,430	$ 230,474	$ 984,883	$ 1,002,970
Other comprehensive loss:
Change in unrealized currency translation adjustments	(22,781)	(40,516)	(7,387)	(27,637)
Change in unrealized investment losses, net of taxes	(118,365)	(315,664)	(50,850)	(1,076,217)
Other comprehensive loss	(141,146)	(356,180)	(58,237)	(1,103,854)
Comprehensive income (loss)	192,284	(125,706)	926,646	(100,884)
Noncontrolling interests	156	(1,595)	(862)	(4,130)
Comprehensive income (loss) to common stockholders	$ 192,440	$ (127,301)	$ 925,784	$ (105,014)

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Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated Other Comprehensive Income (Loss)	Unrealized investment gain	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		$ 105,803	$ 981,104	$ 9,015,135	$ (281,955)	$ 90,900	$ (372,855)	$ (3,167,076)	$ 14,719
Beginning of period at Dec. 31, 2021		105,803	981,104	9,015,135	(281,955)	90,900	(372,855)	(3,167,076)	14,719
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(30,751)
Restricted stock units expensed			34,450
Net income before noncontrolling interests	$ 1,002,970			998,839					4,131
Dividends ($0.61, $0.10, $1.32 and $0.79 per share, respectively)				(208,737)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(1,076,217)					(1,055,628)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(20,590)
Net change in period	(27,637)						(27,637)
Stock exercised/vested								9,679
Stock repurchased								(6,570)
Other	0
(Distributions) contributions									5,061
Other comprehensive loss, net of tax	$ (1,103,854)				(1,103,854)		(27,637)		(1)
End of period at Sep. 30, 2022			984,803	9,805,237	(1,385,810)	(985,318)	(400,492)	(3,163,967)	23,910
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.79
Cumulative effect adjustment resulting from changes in accounting principles		105,803	1,001,093	9,602,948	(1,029,630)	(669,654)	(359,976)	(3,165,729)	22,388
Beginning of period at Jun. 30, 2022		105,803	1,001,093	9,602,948	(1,029,630)	(669,654)	(359,976)	(3,165,729)	22,388
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(28,381)
Restricted stock units expensed			12,091
Net income before noncontrolling interests	$ 230,474			228,879					1,595
Dividends ($0.61, $0.10, $1.32 and $0.79 per share, respectively)				(26,590)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(315,664)					(311,659)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(4,005)
Net change in period	(40,516)						(40,516)
Stock exercised/vested								8,332
Stock repurchased								(6,570)
Other	0
(Distributions) contributions									(73)
Other comprehensive loss, net of tax	$ (356,180)				(356,180)		(40,516)		0
End of period at Sep. 30, 2022			984,803	9,805,237	(1,385,810)	(985,318)	(400,492)	(3,163,967)	23,910
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.10
Cumulative effect adjustment resulting from changes in accounting principles			984,803	9,805,237	(1,385,810)	(985,318)	(400,492)	(3,163,967)	23,910
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,768,161	105,803	997,534	10,161,005	(1,264,581)	(892,905)	(371,676)	(3,251,429)	19,829
Beginning of period at Dec. 31, 2022	6,768,161	105,803	997,534	10,161,005	(1,264,581)	(892,905)	(371,676)	(3,251,429)	19,829
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(25,228)
Restricted stock units expensed			35,995
Net income before noncontrolling interests	984,883			984,020					863
Dividends ($0.61, $0.10, $1.32 and $0.79 per share, respectively)				(344,328)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(50,850)					(47,757)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(3,094)
Net change in period	(7,387)						(7,387)
Stock exercised/vested								9,461
Stock repurchased								(430,536)
Other	(3,899)
(Distributions) contributions									(6,361)
Other comprehensive loss, net of tax	(58,237)				(58,237)		(7,387)		(1)
End of period at Sep. 30, 2023	$ 6,929,909		1,008,301	10,800,697	(1,322,819)	(943,756)	(379,063)	(3,676,403)	14,330
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 1.32
Cumulative effect adjustment resulting from changes in accounting principles		105,803	1,020,818	10,624,518	(1,181,673)	(825,391)	(356,282)	(3,682,281)	21,167
Beginning of period at Jun. 30, 2023		$ 105,803	1,020,818	10,624,518	(1,181,673)	(825,391)	(356,282)	(3,682,281)	21,167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(25,226)
Restricted stock units expensed			12,709
Net income before noncontrolling interests	$ 333,430			333,586					(156)
Dividends ($0.61, $0.10, $1.32 and $0.79 per share, respectively)				(157,407)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(118,365)					(108,121)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(10,244)
Net change in period	(22,781)						(22,781)
Stock exercised/vested								8,469
Stock repurchased								(2,917)
Other	326
(Distributions) contributions									(6,681)
Other comprehensive loss, net of tax	(141,146)				(141,146)		(22,781)		0
End of period at Sep. 30, 2023	$ 6,929,909		1,008,301	10,800,697	(1,322,819)	(943,756)	(379,063)	(3,676,403)	14,330
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.61
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,929,909		$ 1,008,301	$ 10,800,697	$ (1,322,819)	$ (943,756)	$ (379,063)	$ (3,676,403)	$ 14,330

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Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 984,020	$ 998,839
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(39,239)	(127,299)
Depreciation and amortization	3,294	46,037
Noncontrolling interests	863	4,131
Investment funds	(5,444)	(121,919)
Stock incentive plans	37,796	36,247
Change in:
Arbitrage trading account	(41,399)	(39,389)
Premiums and fees receivable	(340,056)	(247,782)
Reinsurance accounts	(194,610)	(187,453)
Deferred policy acquisition costs	(93,270)	(92,724)
Income taxes	49,722	(111,231)
Reserves for losses and loss expenses	1,288,975	1,225,679
Unearned premiums	608,300	551,894
Other	(27,790)	(161,727)
Net cash from operating activities	2,231,162	1,773,303
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	877,019	1,638,049
Proceeds from sale of equity securities	161,470	20,057
Distributions from (contributions to) investment funds	8,385	(72,925)
Proceeds from maturities and prepayments of fixed maturity securities	2,654,140	3,916,331
Purchase of fixed maturity securities	(5,091,866)	(7,694,663)
Purchase of equity securities	(63,815)	(340,158)
Real estate additions	(15,158)	(18,670)
Change in loans receivable	12,796	2,066
Net purchases of property, furniture and equipment	(42,127)	(35,270)
Change in balances due to security brokers	8,224	177,457
Cash received in connection with business disposition	94,076	906,789
Payment for business purchased net of cash acquired	0	(49,572)
Other	320	94
Net cash used in investing activities	(1,396,536)	(1,550,415)
CASH USED IN FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(1,954)	(426,503)
Net proceeds from issuance of debt	1,100	2,181
Cash dividends to common stockholders	(186,921)	(182,147)
Purchase of common treasury shares	(430,536)	(6,570)
Other, net	(20,545)	(21,808)
Net cash used in financing activities	(638,856)	(634,847)
Net impact on cash due to change in foreign exchange rates	959	(26,134)
Net change in cash and cash equivalents	196,728	(438,093)
Cash and cash equivalents at beginning of period	1,449,346	1,568,843
Cash and cash equivalents at end of period	$ 1,646,074	$ 1,130,750

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Consolidated Statements of Comprehensive (Loss) Income

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Consolidated Statements of Comprehensive (Loss) Income

Consolidated Statements of Comprehensive (Loss) Income

    The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"):

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(892,905)		$	(371,676)	$	(1,264,581)
Other comprehensive loss before reclassifications	(103,087)			(7,387)		(110,474)
Amounts reclassified from AOCI	52,237			—		52,237
Other comprehensive loss	(50,850)			(7,387)		(58,237)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	66,123	(1)	$	—	$	66,123
Tax effect	(13,886)		(2)	—		(13,886)
After-tax amounts reclassified	$	52,237		$	—	$	52,237
Other comprehensive loss
Pre-tax	$	(62,476)		$	(7,387)	$	(69,863)
Tax effect	11,626			—		11,626
Other comprehensive loss	$	(50,850)		$	(7,387)	$	(58,237)
As of and for the three months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(825,391)		$	(356,282)	$	(1,181,673)
Other comprehensive loss before reclassifications	(133,018)			(22,781)		(155,799)
Amounts reclassified from AOCI	14,653			—		14,653
Other comprehensive loss	(118,365)			(22,781)		(141,146)
Unrealized investment loss related to noncontrolling interest	—			—		—
Ending balance	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	18,548	(1)	$	—	$	18,548
Tax effect	(3,895)		(2)	—		(3,895)
After-tax amounts reclassified	$	14,653		$	—	$	14,653
Other comprehensive loss
Pre-tax	$	(150,455)		$	(22,781)	$	(173,236)
Tax effect	32,090			—		32,090
Other comprehensive loss	$	(118,365)		$	(22,781)	$	(141,146)

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2022
Changes in AOCI
Beginning of period	$	90,900		$	(372,855)	$	(281,955)
Other comprehensive loss before reclassifications	(1,134,657)			(27,637)		(1,162,294)
Amounts reclassified from AOCI	58,440			—		58,440
Other comprehensive loss	(1,076,217)			(27,637)		(1,103,854)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	73,975	(1)	$	—	$	73,975
Tax effect	(15,535)		(2)	—		(15,535)
After-tax amounts reclassified	$	58,440		$	—	$	58,440
Other comprehensive loss
Pre-tax	$	(1,365,064)		$	(27,637)	$	(1,392,701)
Tax effect	288,847			—		288,847
Other comprehensive loss	$	(1,076,217)		$	(27,637)	$	(1,103,854)
As of and for the three months ended September 30, 2022
Changes in AOCI
Beginning of period	$	(669,654)		$	(359,976)	$	(1,029,630)
Other comprehensive loss before reclassifications	(335,034)			(40,516)		(375,550)
Amounts reclassified from AOCI	19,370			—		19,370
Other comprehensive loss	(315,664)			(40,516)		(356,180)
Unrealized investment loss related to noncontrolling interest	—					—
Ending balance	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	24,519	(1)	$	—	$	24,519
Tax effect	(5,149)		(2)	—		(5,149)
After-tax amounts reclassified	$	19,370		$	—	$	19,370
Other comprehensive loss
Pre-tax	$	(394,832)		$	(40,516)	$	(435,348)
Tax effect	79,168			—		79,168
Other comprehensive loss	$	(315,664)		$	(40,516)	$	(356,180)

____________

(1) Net investment (losses) gains in the consolidated statements of income.

(2) Income tax expense in the consolidated statements of income.

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Statements of Cash Flows	9 Months Ended
	Sep. 30, 2023
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flows	Statements of Cash Flows    Interest payments were $79,336,000 and $115,756,000 for the nine months ended September 30, 2023 and 2022, respectively. Income taxes paid were $180,000,000 and $263,971,000 for the nine months ended September 30, 2023 and 2022, respectively.

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General

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

General

General

    The unaudited consolidated financial statements, which include the accounts of W. R. Berkley Corporation and its subsidiaries (the “Company”), have been prepared on the basis of U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. Reclassifications have been made in the 2022 financial statements as originally reported to conform to the presentation of the 2023 financial statements. For the for nine months ended September 30, 2022, the Company did not correct the proceeds from sale of fixed maturity securities and purchase of fixed maturity securities lines within the consolidated statements of cash flows for an incremental inter-company elimination as the effects were not material and had no impact on the total amount of investing activities.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the revenues and expenses reflected during the reporting period. For further information related to areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective income tax rate differs from the federal income tax rate of 21% primarily due to tax benefits related to equity-based compensation and tax-exempt investment income, which was partially offset by state income taxes.

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Per Share Data

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Per Share Data

Per Share Data

    The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 11,416,856 and 11,592,699 common shares held in a grantor trust as of September 30, 2023 and 2022, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.

    The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:

	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(In thousands)	2023	2022	2023	2022
Basic	269,191	277,192	271,656	276,928
Diluted	271,439	279,642	274,146	279,644

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Recent Accounting Pronouncements and Accounting Policies

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Recent Accounting Pronouncements and Accounting Policies

Recent Accounting Pronouncements and Accounting Policies

Recently adopted accounting pronouncements:

    All accounting and reporting standards that became effective in 2023 were either not applicable to the Company or their adoption did not have a material impact on the Company.

Accounting and reporting standards that are not yet effective:

    All recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

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Investments In Fixed Maturity Securities

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Investments In Fixed Maturity Securities

Investments in Fixed Maturity Securities

    At September 30, 2023 and December 31, 2022, investments in fixed maturity securities were as follows:

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
September 30, 2023
Held to maturity:
State and municipal	$	49,847	$	(48)	$	1,825	$	—	$	51,624	$	49,799
Residential mortgage-backed	3,029		—		19		—		3,048		3,029
Total held to maturity	52,876		(48)		1,844		—		54,672		52,828
Available for sale:
U.S. government and government agency	1,546,889		—		2,077		(81,767)		1,467,199		1,467,199
State and municipal:
Special revenue	1,771,219		—		2,287		(126,585)		1,646,921		1,646,921
State general obligation	378,650		—		1,247		(23,727)		356,170		356,170
Pre-refunded	103,219		—		202		(827)		102,594		102,594
Corporate backed	194,976		(821)		159		(14,341)		179,973		179,973
Local general obligation	401,286		—		1,767		(17,713)		385,340		385,340
Total state and municipal	2,849,350		(821)		5,662		(183,193)		2,670,998		2,670,998
Mortgage-backed:
Residential	1,660,790		(24)		399		(214,381)		1,446,784		1,446,784
Commercial	651,966		(2,076)		11		(20,389)		629,512		629,512
Total mortgage-backed	2,312,756		(2,100)		410		(234,770)		2,076,296		2,076,296
Asset-backed	4,197,235		(1,502)		750		(109,025)		4,087,458		4,087,458
Corporate:
Industrial	3,567,020		—		5,026		(227,479)		3,344,567		3,344,567
Financial	2,813,603		(5,406)		1,362		(130,312)		2,679,247		2,679,247
Utilities	683,468		(364)		164		(39,991)		643,277		643,277
Other	593,466		—		134		(11,877)		581,723		581,723
Total corporate	7,657,557		(5,770)		6,686		(409,659)		7,248,814		7,248,814
Foreign government	1,616,110		(36,171)		1,361		(149,588)		1,431,712		1,431,712
Total available for sale	20,179,897		(46,364)		16,946		(1,168,002)		18,982,477		18,982,477
Total investments in fixed maturity securities	$	20,232,773	$	(46,412)	$	18,790	$	(1,168,002)	$	19,037,149	$	19,035,305

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
December 31, 2022
Held to maturity:
State and municipal	$	47,802	$	(114)	$	4,239	$	—	$	51,927	$	47,688
Residential mortgage-backed	3,608		—		38		—		3,646		3,608
Total held to maturity	51,410		(114)		4,277		—		55,573		51,296
Available for sale:
U.S. government and government agency	960,479		—		937		(69,158)		892,258		892,258
State and municipal:
Special revenue	1,837,309		—		3,662		(119,474)		1,721,497		1,721,497
State general obligation	387,709		—		2,651		(21,335)		369,025		369,025
Pre-refunded	156,106		—		2,741		(7)		158,840		158,840
Corporate backed	210,228		—		334		(10,923)		199,639		199,639
Local general obligation	454,983		—		2,967		(16,853)		441,097		441,097
Total state and municipal	3,046,335		—		12,355		(168,592)		2,890,098		2,890,098
Mortgage-backed:
Residential	1,308,019		(18)		395		(171,595)		1,136,801		1,136,801
Commercial	547,757		—		215		(19,363)		528,609		528,609
Total mortgage-backed securities	1,855,776		(18)		610		(190,958)		1,665,410		1,665,410
Asset-backed	4,132,365		—		2,730		(152,322)		3,982,773		3,982,773
Corporate:
Industrial	3,491,645		(1,704)		4,439		(241,381)		3,252,999		3,252,999
Financial	2,585,247		(2,997)		5,505		(117,383)		2,470,372		2,470,372
Utilities	586,066		—		1,307		(36,325)		551,048		551,048
Other	441,230		—		—		(11,657)		429,573		429,573
Total corporate	7,104,188		(4,701)		11,251		(406,746)		6,703,992		6,703,992
Foreign government	1,564,930		(32,633)		4,283		(135,058)		1,401,522		1,401,522
Total available for sale	18,664,073		(37,352)		32,166		(1,122,834)		17,536,053		17,536,053
Total investments in fixed maturity securities	$	18,715,483	$	(37,466)	$	36,443	$	(1,122,834)	$	17,591,626	$	17,587,349

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	114	$	387
Provision for expected credit losses	(66)		(266)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	53	$	127
Provision for expected credit losses	(5)		(6)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	32,633	$	4,701	$	18	$	—	$	—	$	37,352	$	22,222	$	16	$	—	$	22,238
Expected credit losses on securities for which credit losses were not previously recorded	—		942		1,766		1,444		821		4,973		1,897		1,205		21		3,123
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,538		134		316		58		—		4,046		9,289		(22)		—		9,267
Reduction due to disposals	—		(7)		—		—		—		(7)		(33)		—		—		(33)
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. During the nine months ended September 30, 2022, the Company increased the allowance for expected credit losses for available for sale securities mainly due to an increase in unrealized losses primarily associated with foreign government securities.

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	33,052	$	8,867	$	885	$	1,444	$	—	$	44,248	$	33,096	$	182	$	—	$	33,278
Expected credit losses on securities for which credit losses were not previously recorded	—		756		905		—		821		2,482		—		1,023		21		1,044
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,119		(3,853)		310		58		—		(366)		279		(6)		—		273
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

The amortized cost and fair value of fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  

(In thousands)	Amortized Cost (1)		Fair Value
Due in one year or less	$	1,818,820	$	1,742,384
Due after one year through five years	9,180,726		8,704,308
Due after five years through ten years	4,308,202		4,074,956
Due after ten years	2,609,192		2,436,157
Mortgage-backed securities	2,315,785		2,079,344
Total	$	20,232,725	$	19,037,149

________________

(1) Amortized cost is reduced by the allowance for expected credit losses of $48 thousand related to held to maturity securities.    At September 30, 2023 and December 31, 2022, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.

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Investments in Equity Securities

9 Months Ended

Sep. 30, 2023

Debt Securities, Available-for-sale [Line Items]

Investments in Equity Securities

Investments in Fixed Maturity Securities

    At September 30, 2023 and December 31, 2022, investments in fixed maturity securities were as follows:

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
September 30, 2023
Held to maturity:
State and municipal	$	49,847	$	(48)	$	1,825	$	—	$	51,624	$	49,799
Residential mortgage-backed	3,029		—		19		—		3,048		3,029
Total held to maturity	52,876		(48)		1,844		—		54,672		52,828
Available for sale:
U.S. government and government agency	1,546,889		—		2,077		(81,767)		1,467,199		1,467,199
State and municipal:
Special revenue	1,771,219		—		2,287		(126,585)		1,646,921		1,646,921
State general obligation	378,650		—		1,247		(23,727)		356,170		356,170
Pre-refunded	103,219		—		202		(827)		102,594		102,594
Corporate backed	194,976		(821)		159		(14,341)		179,973		179,973
Local general obligation	401,286		—		1,767		(17,713)		385,340		385,340
Total state and municipal	2,849,350		(821)		5,662		(183,193)		2,670,998		2,670,998
Mortgage-backed:
Residential	1,660,790		(24)		399		(214,381)		1,446,784		1,446,784
Commercial	651,966		(2,076)		11		(20,389)		629,512		629,512
Total mortgage-backed	2,312,756		(2,100)		410		(234,770)		2,076,296		2,076,296
Asset-backed	4,197,235		(1,502)		750		(109,025)		4,087,458		4,087,458
Corporate:
Industrial	3,567,020		—		5,026		(227,479)		3,344,567		3,344,567
Financial	2,813,603		(5,406)		1,362		(130,312)		2,679,247		2,679,247
Utilities	683,468		(364)		164		(39,991)		643,277		643,277
Other	593,466		—		134		(11,877)		581,723		581,723
Total corporate	7,657,557		(5,770)		6,686		(409,659)		7,248,814		7,248,814
Foreign government	1,616,110		(36,171)		1,361		(149,588)		1,431,712		1,431,712
Total available for sale	20,179,897		(46,364)		16,946		(1,168,002)		18,982,477		18,982,477
Total investments in fixed maturity securities	$	20,232,773	$	(46,412)	$	18,790	$	(1,168,002)	$	19,037,149	$	19,035,305

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
December 31, 2022
Held to maturity:
State and municipal	$	47,802	$	(114)	$	4,239	$	—	$	51,927	$	47,688
Residential mortgage-backed	3,608		—		38		—		3,646		3,608
Total held to maturity	51,410		(114)		4,277		—		55,573		51,296
Available for sale:
U.S. government and government agency	960,479		—		937		(69,158)		892,258		892,258
State and municipal:
Special revenue	1,837,309		—		3,662		(119,474)		1,721,497		1,721,497
State general obligation	387,709		—		2,651		(21,335)		369,025		369,025
Pre-refunded	156,106		—		2,741		(7)		158,840		158,840
Corporate backed	210,228		—		334		(10,923)		199,639		199,639
Local general obligation	454,983		—		2,967		(16,853)		441,097		441,097
Total state and municipal	3,046,335		—		12,355		(168,592)		2,890,098		2,890,098
Mortgage-backed:
Residential	1,308,019		(18)		395		(171,595)		1,136,801		1,136,801
Commercial	547,757		—		215		(19,363)		528,609		528,609
Total mortgage-backed securities	1,855,776		(18)		610		(190,958)		1,665,410		1,665,410
Asset-backed	4,132,365		—		2,730		(152,322)		3,982,773		3,982,773
Corporate:
Industrial	3,491,645		(1,704)		4,439		(241,381)		3,252,999		3,252,999
Financial	2,585,247		(2,997)		5,505		(117,383)		2,470,372		2,470,372
Utilities	586,066		—		1,307		(36,325)		551,048		551,048
Other	441,230		—		—		(11,657)		429,573		429,573
Total corporate	7,104,188		(4,701)		11,251		(406,746)		6,703,992		6,703,992
Foreign government	1,564,930		(32,633)		4,283		(135,058)		1,401,522		1,401,522
Total available for sale	18,664,073		(37,352)		32,166		(1,122,834)		17,536,053		17,536,053
Total investments in fixed maturity securities	$	18,715,483	$	(37,466)	$	36,443	$	(1,122,834)	$	17,591,626	$	17,587,349

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	114	$	387
Provision for expected credit losses	(66)		(266)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	53	$	127
Provision for expected credit losses	(5)		(6)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	32,633	$	4,701	$	18	$	—	$	—	$	37,352	$	22,222	$	16	$	—	$	22,238
Expected credit losses on securities for which credit losses were not previously recorded	—		942		1,766		1,444		821		4,973		1,897		1,205		21		3,123
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,538		134		316		58		—		4,046		9,289		(22)		—		9,267
Reduction due to disposals	—		(7)		—		—		—		(7)		(33)		—		—		(33)
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. During the nine months ended September 30, 2022, the Company increased the allowance for expected credit losses for available for sale securities mainly due to an increase in unrealized losses primarily associated with foreign government securities.

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	33,052	$	8,867	$	885	$	1,444	$	—	$	44,248	$	33,096	$	182	$	—	$	33,278
Expected credit losses on securities for which credit losses were not previously recorded	—		756		905		—		821		2,482		—		1,023		21		1,044
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,119		(3,853)		310		58		—		(366)		279		(6)		—		273
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

The amortized cost and fair value of fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  

(In thousands)	Amortized Cost (1)		Fair Value
Due in one year or less	$	1,818,820	$	1,742,384
Due after one year through five years	9,180,726		8,704,308
Due after five years through ten years	4,308,202		4,074,956
Due after ten years	2,609,192		2,436,157
Mortgage-backed securities	2,315,785		2,079,344
Total	$	20,232,725	$	19,037,149

________________

(1) Amortized cost is reduced by the allowance for expected credit losses of $48 thousand related to held to maturity securities.    At September 30, 2023 and December 31, 2022, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.

Equity securities

Debt Securities, Available-for-sale [Line Items]

Investments in Equity Securities

Investments in Equity Securities

    At September 30, 2023 and December 31, 2022, investments in equity securities were as follows:

(In thousands)	Cost		Gross Unrealized				Fair Value		Carrying Value
			Gains		Losses
September 30, 2023
Common stocks	$	792,512	$	209,979	$	(41,058)	$	961,433	$	961,433
Preferred stocks	273,376		2,383		(55,131)		220,628		220,628
Total	$	1,065,888	$	212,362	$	(96,189)	$	1,182,061	$	1,182,061
December 31, 2022
Common stocks	$	855,987	$	192,165	$	(65,401)	$	982,751	$	982,751
Preferred stocks	259,341		1,053		(57,251)		203,143		203,143
Total	$	1,115,328	$	193,218	$	(122,652)	$	1,185,894	$	1,185,894

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Arbitrage Trading Account

9 Months Ended

Sep. 30, 2023

Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]

Arbitrage Trading Account

Arbitrage Trading Account

    At September 30, 2023 and December 31, 2022, the fair and carrying values of the arbitrage trading account were $825 million and $944 million, respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less).

    The Company uses put options and call options in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options are reported at fair value. As of September 30, 2023, the fair value of long option contracts outstanding was $256 thousand (notional amount of $50 million) and the fair value of short option contracts was $6 million (notional amount of $50 million). Other than with respect to the use of these trading account securities, the Company does not make use of derivatives.

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Net Investment Income

9 Months Ended

Sep. 30, 2023

Net Investment Income [Abstract]

Net Investment Income

Net Investment Income

    Net investment income consisted of the following: 

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Investment income (loss) earned on:
Fixed maturity securities, including cash and cash equivalents and loans receivable	$	239,727	$	146,051	$	653,200	$	371,724
Arbitrage trading account (1)	17,876		10,694		53,168		24,008
Equity securities	12,714		14,650		41,714		38,303
Investment funds	4,450		36,045		5,444		121,919
Real estate	(1,986)		(2,297)		(7,821)		(1,702)
Gross investment income	272,781		205,143		745,705		554,252
Investment expense	(1,837)		(2,327)		(6,211)		(6,350)
Net investment income	$	270,944	$	202,816	$	739,494	$	547,902

(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.

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Investment Funds

9 Months Ended

Sep. 30, 2023

Equity Method Investments and Joint Ventures [Abstract]

Investment Funds

Investment Funds

    The Company evaluates whether it is an investor in a variable interest entity ("VIE"). Such entities do not have sufficient equity at risk to finance their activities without additional subordinated financial support, or the equity investors, as a group, do not have the characteristics of a controlling financial interest (primary beneficiary). The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE's capital structure, contractual terms, nature of the VIE's operations and purpose, and the Company's relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE and on an ongoing basis. The Company is not the primary beneficiary in any of its investment funds, and accordingly, carries its interests in investment funds under the equity method of accounting.    

    The Company’s maximum exposure to loss with respect to these investments is limited to the carrying amount reported on the Company’s consolidated balance sheet and its unfunded commitments, which were $353 million as of September 30, 2023.

    Investment funds consisted of the following:

	Carrying Value as of				Income (Loss) from Investment Funds
	September 30,		December 31,		For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Financial services	$	429,889	$	465,683	$	(15,606)	$	27,472
Transportation	336,020		336,753		37,894		48,249
Real Estate	191,445		204,644		(5,062)		42,708
Infrastructure	124,528		115,428		7,813		1,277
Energy	115,349		116,432		3,921		1,966
Other funds	403,264		369,608		(23,516)		247
Total	$	1,600,495	$	1,608,548	$	5,444	$	121,919

    The Company's share of the earnings or losses from investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

Financial services investment funds include the minority investment in Lifson Re, a Bermuda reinsurance company. Effective January 1, 2021, Lifson Re participated on a fully collateralized basis in a majority of the Company’s reinsurance placements for a 22.5% share of placed amounts. The percentage increased from 22.5% to 30% effective July 1, 2022. This pertains to all traditional reinsurance/retrocessional placements for both property and casualty business where there is more than one open market reinsurer participating. For the nine months ended September 30, 2023 and 2022, the Company ceded approximately $348 million and $308 million, respectively, of written premiums to Lifson Re.

Other funds include deferred compensation trust assets of $31 million and $30 million as of September 30, 2023 and December 31, 2022, respectively. These assets support other liabilities reflected in the balance sheet of an equal amount for employees who have elected to defer a portion of their compensation. The change in the net asset value of the trust is recorded in other funds within net investment income with an offsetting equal amount within corporate expenses.

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Real Estate

9 Months Ended

Sep. 30, 2023

Real Estate [Abstract]

Real Estate

Real Estate

    Investment in real estate represents directly owned property held for investment, as follows:

	Carrying Value
	September 30,		December 31,
(In thousands)	2023		2022
Properties in operation	$	1,043,419	$	1,114,167
Properties under development	227,126		226,455
Total	$	1,270,545	$	1,340,622

    As of September 30, 2023, properties in operation included a long-term ground lease in Washington, D.C., an office complex in New York City and the completed portion of a mixed-use project in Washington D.C. Properties in operation are

net of accumulated depreciation and amortization of $31,039,000 and $33,206,000 as of September 30, 2023 and December 31, 2022, respectively. Related depreciation expense was $6,667,000 and $9,934,000 for the nine months ended September 30, 2023 and 2022, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $8,368,709 in 2023, $35,249,642 in 2024, $34,435,718 in 2025, $32,583,382 in 2026, $32,074,240 in 2027, $32,823,410 in 2028 and $505,344,609 thereafter.

The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

During the first quarter of 2022, the Company sold a real estate investment in London (proceeds from the real estate and related entity is presented on the business disposition line within the Consolidated Statements of Cash Flows).

    A mixed-use project in Washington, D.C. had been under development in 2023 and 2022, with the completed portion reported in properties in operation as of September 30, 2023.

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Loans Receivable

9 Months Ended

Sep. 30, 2023

Receivables [Abstract]

Loans Receivable

Loans Receivable

At September 30, 2023 and December 31, 2022, loans receivable were as follows:

(In thousands)	September 30, 2023		December 31, 2022
Amortized cost (net of allowance for expected credit losses):
Real estate loans	$	159,857	$	173,616
Commercial loans	17,893		19,386
Total	$	177,750	$	193,002
Fair value:
Real estate loans	$	156,407	$	168,595
Commercial loans	17,893		19,386
Total	$	174,300	$	187,981

The real estate loans are secured by commercial and residential real estate primarily located in London and New York. These loans generally earn interest at fixed or stepped interest rates and have maturities through 2026. The commercial loans are with small business owners who have secured the related financing with the assets of the business. Commercial loans primarily earn interest on a fixed basis and have varying maturities generally not exceeding 10 years.

Loans receivable in non-accrual status were none as of both September 30, 2023 and December 31, 2022, respectively.

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the nine months ended September 30, 2023 and 2022:

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	1,100	$	691	$	1,791	$	1,362	$	356	$	1,718
Change in expected credit losses	2,302		(84)		2,218		(200)		474		274
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses due to changes in economic assumptions utilized in its credit loss model. During the nine months ended September 30, 2022, the Company increased the allowance primarily due to an increase in the weighted average life of the loans receivable portfolio.

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended September 30, 2023 and 2022:

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	3,658	$	892	$	4,550	$	1,228	$	947	$	2,175
Change in expected credit losses	(256)		(285)		(541)		(66)		(117)		(183)
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

The Company monitors the performance of its loans receivable and assesses the ability of the borrower to pay principal and interest based upon loan structure, underlying property values, cash flow and related financial and operating performance of the property and market conditions.

    In evaluating the real estate loans, the Company considers their credit quality indicators, including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and performance with respect to loan terms, the position in the capital structure, the overall leverage in the capital structure and other market conditions.

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Net Investment (Losses) Gains

9 Months Ended

Sep. 30, 2023

Realized and Unrealized Investment Gains (Losses) [Abstract]

Net Investment (Losses) Gains

Net Investment (Losses) Gains

     Net investment (losses) gains were as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Net investment (losses) gains:
Fixed maturity securities:
Gains	$	299	$	1,053	$	1,357	$	3,405
Losses	(2,700)		(2,309)		(24,470)		(8,752)
Equity securities (1):
Net realized gains on investment sales (2)	23,631		—		135,763		946
Change in unrealized (losses) gains	(19,059)		(50,384)		45,605		(88,701)
Investment funds	(3,329)		(1,717)		(3,417)		(6,241)
Real estate (3) (4)	(24,234)		9,026		(68,944)		295,576
Loans receivable	(1,428)		—		(1,428)		(32)
Other	(14,035)		(21,951)		(34,063)		(56,537)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(40,855)		(66,282)		50,403		139,664
Change in allowance for expected credit losses on investments:
Fixed maturity securities	(2,112)		(1,311)		(8,946)		(12,091)
Loans receivable	541		183		(2,218)		(274)
Change in allowance for expected credit losses on investments	(1,571)		(1,128)		(11,164)		(12,365)
Net investment (losses) gains	(42,426)		(67,410)		39,239		127,299
Income tax benefit (expense)	9,405		14,456		(8,033)		(26,466)
After-tax net investment (losses) gains	$	(33,021)	$	(52,954)	$	31,206	$	100,833

Change in unrealized investment (losses) gains on available for sale securities:
Fixed maturity securities without allowance for expected credit losses	$	(136,388)	$	(385,503)	$	(57,293)	$	(1,335,413)
Fixed maturity securities with allowance for expected credit losses	(10,244)		(4,005)		(3,094)		(20,590)
Investment funds	(3,217)		(5,031)		(818)		(7,863)
Other	(606)		(293)		(1,271)		(1,198)
Total change in unrealized investment losses	(150,455)		(394,832)		(62,476)		(1,365,064)
Income tax benefit	32,090		79,168		11,626		288,847
Noncontrolling interests	—		—		(1)		(1)
After-tax change in unrealized investment losses of available for sale securities	$	(118,365)	$	(315,664)	$	(50,851)	$	(1,076,218)

______________________

(1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized (losses) gains consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held.

(2) In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million on the sale (proceeds from the sale is presented on the business disposition line within the Consolidated Statements of Cash Flows).

(3) The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

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Fixed Maturity Securities In An Unrealized Loss Position

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Fixed Maturity Securities In An Unrealized Loss Position

Fixed Maturity Securities in an Unrealized Loss Position

    The following tables summarize all fixed maturity securities in an unrealized loss position at September 30, 2023 and December 31, 2022 by the length of time those securities have been continuously in an unrealized loss position:

	Less Than 12 Months				12 Months or Greater				Total
(In thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
September 30, 2023
U.S. government and government agency	$	605,944	$	17,390	$	592,215	$	64,377	$	1,198,159	$	81,767
State and municipal	645,642		15,255		1,728,892		167,938		2,374,534		183,193
Mortgage-backed	688,848		17,058		1,296,384		217,712		1,985,232		234,770
Asset-backed	1,025,656		8,774		2,584,224		100,251		3,609,880		109,025
Corporate	2,091,830		46,758		4,695,101		362,901		6,786,931		409,659
Foreign government	563,657		15,038		779,455		134,550		1,343,112		149,588
Fixed maturity securities	$	5,621,577	$	120,273	$	11,676,271	$	1,047,729	$	17,297,848	$	1,168,002
December 31, 2022
U.S. government and government agency	$	285,391	$	10,219	$	453,520	$	58,939	$	738,911	$	69,158
State and municipal	1,720,443		89,272		598,797		79,320		2,319,240		168,592
Mortgage-backed	1,099,549		75,430		473,318		115,528		1,572,867		190,958
Asset-backed	1,569,647		48,390		2,176,638		103,932		3,746,285		152,322
Corporate	3,690,856		150,115		2,349,281		256,631		6,040,137		406,746
Foreign government	477,672		29,815		711,786		105,243		1,189,458		135,058
Fixed maturity securities	$	8,843,558	$	403,241	$	6,763,340	$	719,593	$	15,606,898	$	1,122,834

    Substantially all of the securities in an unrealized loss position are rated investment grade, except for the securities in the foreign government classification. A significant amount of the unrealized loss on foreign government securities is the result of changes in currency exchange rates. 

    A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2023 is presented in the table below:

($ in thousands)	Number of Securities	Aggregate Fair Value		Gross Unrealized Loss
Foreign government	44	$	88,668	$	91,468
Corporate	26	35,644		3,523
State and municipal	5	22,866		6,374
Mortgage-backed	15	4,328		214
Asset-backed	5	244		107
Total	95	$	151,750	$	101,686

    For fixed maturity securities that management does not intend to sell or to be required to sell, the portion of the decline in value that is considered to be due to credit factors is recognized in earnings, and the portion of the decline in value that is considered to be due to non-credit factors is recognized in other comprehensive income (loss).

     The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due.

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Fair Value Measurements

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

    The Company’s fixed maturity available for sale securities, equity securities and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows:

Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable.

Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available.

    Substantially all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation.

    If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.

    For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate.

    The following tables present the assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 by level:

(In thousands)	Total		Level 1		Level 2		Level 3
September 30, 2023
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	1,467,199	$	—	$	1,467,199	$	—
State and municipal	2,670,998		—		2,670,998		—
Mortgage-backed	2,076,296		—		2,076,296		—
Asset-backed	4,087,458		—		4,087,458		—
Corporate	7,248,814		—		7,248,814		—
Foreign government	1,431,712		—		1,431,712		—
Total fixed maturity securities available for sale	18,982,477		—		18,982,477		—
Equity securities:
Common stocks	961,433		958,202		1,060		2,171
Preferred stocks	220,628		—		216,930		3,698
Total equity securities	1,182,061		958,202		217,990		5,869
Arbitrage trading account	825,049		614,995		206,536		3,518
Total	$	20,989,587	$	1,573,197	$	19,407,003	$	9,387
Liabilities:
Trading account securities sold but not yet purchased	$	7,538	$	7,538	$	—	$	—
December 31, 2022
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	892,258	$	—	$	892,258	$	—
State and municipal	2,890,098		—		2,890,098		—
Mortgage-backed	1,665,410		—		1,665,410		—
Asset-backed	3,982,773		—		3,982,773		—
Corporate	6,703,992		—		6,703,992		—
Foreign government	1,401,522		—		1,401,522		—
Total fixed maturity securities available for sale	17,536,053		—		17,536,053		—
Equity securities:
Common stocks	982,751		978,991		1,161		2,599
Preferred stocks	203,143		—		191,844		11,299
Total equity securities	1,185,894		978,991		193,005		13,898
Arbitrage trading account	944,230		822,192		118,448		3,590
Total	$	19,666,177	$	1,801,183	$	17,847,506	$	17,488
Liabilities:
Trading account securities sold but not yet purchased	$	—	$	—	$	—	$	—

    The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2023 and for the year ended December 31, 2022:

Gains (Losses) Included In:
(In thousands)	Beginning Balance		Earnings (Losses)		Other Comprehensive Income (Losses)		Impairments		Purchases		Sales		Paydowns / Maturities		Transfers In / (Out)		Ending Balance
Nine Months Ended September 30, 2023
Assets:
Equity securities:
Common stocks	$	2,599	$	(428)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,171
Preferred stocks	11,299		—		—		(7,601)		—		—		—		—		3,698
Total	13,898		(428)		—		(7,601)		—		—		—		—		5,869
Arbitrage trading account	3,590		(72)		—		—		—		—		—		—		3,518
Total	$	17,488	$	(500)	$	—	$	(7,601)	$	—	$	—	$	—	$	—	$	9,387
Year Ended December 31, 2022
Assets:
Equity securities:
Common stocks	$	9,294	$	(6,695)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,599
Preferred stocks	11,296		3		—		—		925		(925)		—		—		11,299
Total	20,590		(6,692)		—		—		925		(925)		—		—		13,898
Arbitrage trading account	—		(179)		—		—		4,686		(917)		—		—		3,590
Total	$	20,590	$	(6,871)	$	—	$	—	$	5,611	$	(1,842)	$	—	$	—	$	17,488

    For the nine months ended September 30, 2023 and for the year ended December 31, 2022, there were no securities transferred into or out of Level 3.

Fair Value of Financial Instruments

    The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:

	September 30, 2023				December 31, 2022
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Fixed maturity securities	$	19,035,305	$	19,037,149	$	17,587,349	$	17,591,626
Equity securities	1,182,061		1,182,061		1,185,894		1,185,894
Arbitrage trading account	825,049		825,049		944,230		944,230
Loans receivable	177,750		174,300		193,002		187,981
Cash and cash equivalents	1,646,074		1,646,074		1,449,346		1,449,346
Trading account receivables from brokers and clearing organizations	401,982		401,982		233,863		233,863
Due from broker	—		—		3,609		3,609
Liabilities:
Due to broker	5,118		5,118		—		—
Trading account securities sold but not yet purchased	7,538		7,538		—		—
Senior notes and other debt	1,828,046		1,321,014		1,828,823		1,439,188
Subordinated debentures	1,008,910		786,798		1,008,371		805,600

    The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

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Reserves for Loss and Loss Expenses

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Reserves for Loss and Loss Expenses

Reserves for Loss and Loss Expenses

    The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities ("IBNR"). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims.

    Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit.

    The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions.

    The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns.

    Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations.

    Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags.

    The key assumptions used in calculating the most recent estimate of the loss reserves are reviewed each quarter and adjusted, to the extent necessary, to reflect the latest reported loss data, current trends and other factors observed.

    The table below provides a reconciliation of the beginning and ending reserve balances:

	September 30,
(In thousands)	2023		2022
Net reserves at beginning of period	$	14,248,879	$	12,848,362
Net provision for losses and loss expenses:
Claims occurring during the current year (1)	4,694,554		4,260,179
Increase in estimates for claims occurring in prior years (2) (3)	27,186		54,632
Loss reserve discount accretion	22,862		24,835
Total	4,744,602		4,339,646
Net payments for claims:
Current year	743,416		643,908
Prior years	2,915,979		2,499,319
Total	3,659,395		3,143,227
Foreign currency translation	(48,162)		(193,755)
Net reserves at end of period	15,285,924		13,851,026
Ceded reserves at end of period	2,987,386		2,689,097
Gross reserves at end of period	$	18,273,310	$	16,540,123

_______________________________________

(1) Claims occurring during the current year are net of loss reserve discounts of $35 million and $26 million for the nine months ended September 30, 2023 and 2022, respectively.

(2) The change in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $12 million and increased by $20 million for the nine months ended September 30, 2023 and 2022, respectively.

(3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Adverse development, net of additional and return premiums, was $20 million and $37 million for the nine months ended September 30, 2023 and 2022, respectively.

The COVID-19 global pandemic impacted, and may further impact, the Company’s loss costs. Accordingly, the ultimate net impact of COVID-19 on the Company’s reserves remains uncertain. As of September 30, 2023, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $354 million, of which $299 million relates to the Insurance segment and $55 million relates to the Reinsurance & Monoline Excess segment. Such $354 million of COVID-19-related losses are considered reported losses. For the nine months ended September 30, 2023, the Company recognized current accident year losses for COVID-19-related claims activity, net of reinsurance, of approximately $670 thousand, all of which relates to the Insurance segment.

During the nine months ended September 30, 2023, adverse prior year development (net of additional and return premiums) of $20 million included $26 million of adverse development for the Insurance segment, partially offset by $6 million of favorable development for the Reinsurance & Monoline Excess segment.

Such adverse development during the nine months ended September 30, 2023 was concentrated in the first quarter, with $24 million of adverse development (net of additional and return premiums) in the first quarter, partially offset by favorable development of $4 million in the second and third quarters. This overall adverse development during the first quarter in both business segments was due to property catastrophe losses related to 2022 events which were still being adjusted and settled. In particular, losses related to U.S. winter storms which occurred during the month of December were a significant driver of the development, as information gathering and evaluation of many of these losses was still ongoing into the new year.

For the Insurance segment, in addition to the property prior year adverse development discussed above, the adverse development during the nine months ended September 30, 2023 included adverse prior year development on casualty lines for the 2016 through 2019 accident years, which was largely offset by favorable prior year development on casualty lines for the 2020 through 2022 accident years. The adverse development on the 2016 through 2019 accident years was concentrated in the general liability line of business, and to a lesser degree professional liability, including medical professional, and commercial auto liability. The development, which particularly impacted business attaching excess of primary policy limits, was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The favorable prior year development on casualty lines for the 2020 through 2022 accident years in the Insurance segment was concentrated in the professional liability, workers’ compensation, and general liability lines of business. Due to uncertainty regarding incurred loss frequency and severity in light of ongoing social inflation and the impacts of the COVID-19 pandemic, the Company set its initial loss ratios for the 2020 through 2022 accident years prudently, and largely maintained these estimates through the end of each respective accident year. The reported loss experience to date for these lines of business for the 2020 through 2022 accident years has been significantly better than was expected, and the Company has begun to react to this favorable emergence as the accident years mature beyond the age of 12 months. However, commercial auto liability experienced adverse prior year development for the 2020 through 2022 accident years, partially offsetting the favorable development discussed above, which was driven by a larger than expected number of large losses reported.

For the Reinsurance & Monoline Excess segment, the favorable development during the nine months ended September 30, 2023 was driven mainly by favorable development in excess workers’ compensation, partially offset by adverse development in property (discussed above) and non-proportional reinsurance assumed liability lines of business. The favorable excess workers’ compensation development was driven by continued lower claim frequency and reported losses relative to our expectations, and to favorable claim settlements. The favorable development was spread across many prior accident years. The adverse development on reinsurance assumed liability was associated primarily with our U.S. assumed reinsurance business, and related to accounts reinsuring excess and umbrella business and construction projects. The adverse development was concentrated mainly in accident years 2017 through 2020.

During the nine months ended September 30, 2022, adverse prior year development (net of additional and return premiums) of $37 million included $33 million for the Insurance segment and $4 million for the Reinsurance & Monoline Excess segment.

The adverse development for the Insurance segment primarily related to COVID-19 losses at two businesses. These businesses wrote policies providing coverage for event cancellation and film production delay which were heavily impacted by losses directly caused by the COVID-19 pandemic. Most of this COVID-19-related adverse development emerged during the third quarter as a result of settlements of claims at values higher than our expectations.

The adverse development mentioned above includes favorable prior year development for the Insurance segment primarily attributable to the 2020 and 2021 accident years and adverse development on the 2015 through 2019 accident years. The favorable development on the 2020 and 2021 accident years was concentrated in the other liability lines of business, including professional liability, products liability, commercial multi-peril liability and workers’ compensation. The Company experienced lower reported claim frequency in these lines of business during 2020 and 2021 relative to historical averages, and continues to experience lower reported incurred losses relative to our expectations for these accident years as they develop during 2022. These trends began in 2020 and we believe were caused by the impacts of the COVID-19 pandemic, including for example, lockdowns, reduced driving/traffic and increased work from home. Due to the ongoing uncertainty regarding the ultimate impacts of the pandemic on accident years 2020 and 2021 incurred losses, the Company has been cautious in reacting to these lower trends in setting and updating its loss ratio estimates for these years. As these accident years have continued to mature, the Company has continued to recognize some of the favorable reported experience in its ultimate loss estimates made during 2022.

The adverse development on the 2015 through 2019 accident years was concentrated in the other liability and professional liability, including medical professional, lines of business, as well as commercial auto liability. The development was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The overall slight adverse development for the Reinsurance & Monoline Excess segment was driven mainly by adverse development in the professional liability and non-proportional reinsurance assumed property and liability lines of business, substantially offset by favorable development in excess workers’ compensation. The adverse development was spread mainly across accident years 2015 through 2021 and was associated primarily with our U.S. assumed reinsurance business and related to accounts insuring construction projects and professional liability exposures. The favorable excess workers’ compensation development was mainly in 2011 and prior accident years, and was driven by a review of the Company’s claim reporting patterns as well as a number of favorable claim settlements relative to expectations.

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Fair Value Of Financial Instruments

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value Of Financial Instruments

Fair Value Measurements

    The Company’s fixed maturity available for sale securities, equity securities and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows:

Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable.

Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available.

    Substantially all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation.

    If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.

    For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate.

    The following tables present the assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 by level:

(In thousands)	Total		Level 1		Level 2		Level 3
September 30, 2023
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	1,467,199	$	—	$	1,467,199	$	—
State and municipal	2,670,998		—		2,670,998		—
Mortgage-backed	2,076,296		—		2,076,296		—
Asset-backed	4,087,458		—		4,087,458		—
Corporate	7,248,814		—		7,248,814		—
Foreign government	1,431,712		—		1,431,712		—
Total fixed maturity securities available for sale	18,982,477		—		18,982,477		—
Equity securities:
Common stocks	961,433		958,202		1,060		2,171
Preferred stocks	220,628		—		216,930		3,698
Total equity securities	1,182,061		958,202		217,990		5,869
Arbitrage trading account	825,049		614,995		206,536		3,518
Total	$	20,989,587	$	1,573,197	$	19,407,003	$	9,387
Liabilities:
Trading account securities sold but not yet purchased	$	7,538	$	7,538	$	—	$	—
December 31, 2022
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	892,258	$	—	$	892,258	$	—
State and municipal	2,890,098		—		2,890,098		—
Mortgage-backed	1,665,410		—		1,665,410		—
Asset-backed	3,982,773		—		3,982,773		—
Corporate	6,703,992		—		6,703,992		—
Foreign government	1,401,522		—		1,401,522		—
Total fixed maturity securities available for sale	17,536,053		—		17,536,053		—
Equity securities:
Common stocks	982,751		978,991		1,161		2,599
Preferred stocks	203,143		—		191,844		11,299
Total equity securities	1,185,894		978,991		193,005		13,898
Arbitrage trading account	944,230		822,192		118,448		3,590
Total	$	19,666,177	$	1,801,183	$	17,847,506	$	17,488
Liabilities:
Trading account securities sold but not yet purchased	$	—	$	—	$	—	$	—

    The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2023 and for the year ended December 31, 2022:

Gains (Losses) Included In:
(In thousands)	Beginning Balance		Earnings (Losses)		Other Comprehensive Income (Losses)		Impairments		Purchases		Sales		Paydowns / Maturities		Transfers In / (Out)		Ending Balance
Nine Months Ended September 30, 2023
Assets:
Equity securities:
Common stocks	$	2,599	$	(428)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,171
Preferred stocks	11,299		—		—		(7,601)		—		—		—		—		3,698
Total	13,898		(428)		—		(7,601)		—		—		—		—		5,869
Arbitrage trading account	3,590		(72)		—		—		—		—		—		—		3,518
Total	$	17,488	$	(500)	$	—	$	(7,601)	$	—	$	—	$	—	$	—	$	9,387
Year Ended December 31, 2022
Assets:
Equity securities:
Common stocks	$	9,294	$	(6,695)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,599
Preferred stocks	11,296		3		—		—		925		(925)		—		—		11,299
Total	20,590		(6,692)		—		—		925		(925)		—		—		13,898
Arbitrage trading account	—		(179)		—		—		4,686		(917)		—		—		3,590
Total	$	20,590	$	(6,871)	$	—	$	—	$	5,611	$	(1,842)	$	—	$	—	$	17,488

    For the nine months ended September 30, 2023 and for the year ended December 31, 2022, there were no securities transferred into or out of Level 3.

Fair Value of Financial Instruments

    The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:

	September 30, 2023				December 31, 2022
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Fixed maturity securities	$	19,035,305	$	19,037,149	$	17,587,349	$	17,591,626
Equity securities	1,182,061		1,182,061		1,185,894		1,185,894
Arbitrage trading account	825,049		825,049		944,230		944,230
Loans receivable	177,750		174,300		193,002		187,981
Cash and cash equivalents	1,646,074		1,646,074		1,449,346		1,449,346
Trading account receivables from brokers and clearing organizations	401,982		401,982		233,863		233,863
Due from broker	—		—		3,609		3,609
Liabilities:
Due to broker	5,118		5,118		—		—
Trading account securities sold but not yet purchased	7,538		7,538		—		—
Senior notes and other debt	1,828,046		1,321,014		1,828,823		1,439,188
Subordinated debentures	1,008,910		786,798		1,008,371		805,600

    The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

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Premiums and Reinsurance Related Information

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Premiums and Reinsurance Related Information

Premiums and Reinsurance Related Information

The following is a summary of insurance and reinsurance financial information:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Written premiums:
Direct	$	3,037,932	$	2,775,236	$	8,762,249	$	8,075,311
Assumed	315,273		306,702		977,047		918,864
Ceded	(504,746)		(504,664)		(1,504,497)		(1,418,012)
Total net premiums written	$	2,848,459	$	2,577,274	$	8,234,799	$	7,576,163
Earned premiums:
Direct	$	2,825,176	$	2,617,680	$	8,217,888	$	7,533,856
Assumed	316,134		318,962		913,795		903,882
Ceded	(499,396)		(494,681)		(1,445,610)		(1,389,533)
Total net premiums earned	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205
Ceded losses and loss expenses incurred	$	320,995	$	347,439	$	970,267	$	905,667
Ceded commissions earned	$	118,207	$	121,721	$	354,148	$	356,157

    The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	30,660	$	25,218
Change in expected credit losses	2,942		5,360
Allowance for expected credit losses, end of period	$	33,602	$	30,578

The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	32,770	$	30,557
Change in expected credit losses	832		21
Allowance for expected credit losses, end of period	$	33,602	$	30,578

The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of an allowance for expected credit losses.

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	8,064	$	7,713
Change in expected credit losses	1,379		286
Allowance for expected credit losses, end of period	$	9,443	$	7,999

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	9,365	$	7,744
Change in expected credit losses	78		255
Allowance for expected credit losses, end of period	$	9,443	$	7,999

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Restricted Stock Units

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Restricted Stock Units

Restricted Stock Units

    Pursuant to its stock incentive plan, the Company may issue restricted stock units ("RSUs") to employees of the Company and its subsidiaries. The RSUs generally vest three to five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $36 million and $34 million for the nine months ended September 30, 2023 and 2022, respectively. A summary of RSUs issued in the nine months ended September 30, 2023 and 2022 follows:

($ in thousands)	Units	Fair Value
2023	1,092,130	$	68,936
2022	1,023,871	$	67,345

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Litigation and Contingent Liabilities	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingent Liabilities	Litigation and Contingent Liabilities    In the ordinary course of business, the Company is subject to disputes, litigation and arbitration arising from its insurance and reinsurance businesses. These matters are generally related to insurance and reinsurance claims and are considered in the establishment of loss and loss expense reserves. In addition, the Company may also become involved in legal actions which seek extra-contractual damages, punitive damages or penalties, including claims alleging bad faith in handling of insurance claims. The Company expects its ultimate liability with respect to such matters will not be material to its financial condition. However, adverse outcomes on such matters are possible, from time to time, and could be material to the Company’s results of operations in any particular financial reporting period.

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Leases

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Leases

Leases

    Lessees are required to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months on the balance sheet. All leases disclosed within this footnote are classified as operating leases. Recognized right-of-use asset and lease liability are reported within other assets and other liabilities, respectively, in the consolidated balance sheet. Lease expense is reported in other operating costs and expenses in the consolidated statement of income and accounted for on a straight-line basis over the lease term.

    To determine the discount rate used to calculate present value of future minimum lease payments, the Company uses its incremental borrowing rate during the lease commencement period in line with the respective lease duration. In certain cases, the Company has the option to renew the lease. Lease renewal future payments are included in the present value of the future minimum lease payments when the Company determines it is reasonably certain to renew.

The main leases entered into by the Company are for office space used by the Company’s operating units across the world. Additionally, the Company, to a lesser extent, has equipment leases mainly for office equipment. Further information relating to operating lease expense and other operating lease information are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Leases:
Lease cost	$	10,122	$	11,299	$	30,448	$	33,649
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	$	11,403	$	11,082	$	33,247	$	33,128
Right-of-use assets obtained in exchange for new lease liabilities	$	6,543	$	1,527	$	14,489	$	21,729

	As of September 30,
($ in thousands)	2023			2022
Right-of-use assets	$	155,662		$	163,940
Lease liabilities	$	188,141		$	199,889
Weighted-average remaining lease term	6.9 years			7.1 years
Weighted-average discount rate	4.55		%	4.50		%

Contractual maturities of the Company’s future minimum lease payments are as follows:

(In thousands)	September 30, 2023
Contractual Maturities:
2023	$	12,171
2024	44,531
2025	36,167
2026	28,933
2027	19,144
Thereafter	74,394
Total undiscounted future minimum lease payments	215,340
Less: Discount impact	27,199
Total lease liability	$	188,141

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Business Segments

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Business Segments

Business Segments

    The Company’s reportable segments include the following two business segments, plus a corporate segment:

•Insurance - predominantly commercial insurance business, including excess and surplus lines, admitted lines and specialty personal lines throughout the United States, as well as insurance business in Asia, Australia, Canada, Continental Europe, Mexico, Scandinavia, South America and the United Kingdom.

•Reinsurance & Monoline Excess - reinsurance business on a facultative and treaty basis, primarily in the United States, the United Kingdom, Continental Europe, Australia, the Asia-Pacific Region and South Africa, as well as operations that solely retain risk on an excess basis.

    The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Income tax expense and benefits are calculated based upon the Company's overall effective tax rate.

    Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment.

	Revenues
(In thousands)	Earned Premiums (1)		Investment Income		Other		Total (2)		Pre-Tax Income (Loss)		Net Income (Loss) to Common Stockholders
Three months ended September 30, 2023
Insurance	$	2,319,435	$	206,792	$	9,143	$	2,535,370	$	415,279	$	329,519
Reinsurance & Monoline Excess	322,479		56,259		—		378,738		106,072		83,314
Corporate, other and eliminations (3)	—		7,893		151,063		158,956		(58,976)		(46,226)
Net investment losses	—		—		(42,426)		(42,426)		(42,426)		(33,021)
Total	$	2,641,914	$	270,944	$	117,780	$	3,030,638	$	419,949	$	333,586
Three months ended September 30, 2022
Insurance	$	2,129,014	$	134,519	$	8,341	$	2,271,874	$	322,312	$	258,521
Reinsurance & Monoline Excess	312,947		55,234		—		368,181		59,561		46,875
Corporate, other and eliminations (3)	—		13,063		138,692		151,755		(28,198)		(23,563)
Net investment losses	—		—		(67,410)		(67,410)		(67,410)		(52,954)
Total	$	2,441,961	$	202,816	$	79,623	$	2,724,400	$	286,265	$	228,879
Nine months ended September 30, 2023
Insurance	$	6,747,704	$	560,182	$	27,570	$	7,335,456	$	1,153,742	$	903,575
Reinsurance & Monoline Excess	938,369		148,525		—		1,086,894		313,290		248,279
Corporate, other and eliminations (3)	—		30,787		429,180		459,967		(253,066)		(199,040)
Net investment gains	—		—		39,239		39,239		39,239		31,206
Total	$	7,686,073	$	739,494	$	495,989	$	8,921,556	$	1,253,205	$	984,020
Nine months ended September 30, 2022
Insurance	$	6,162,005	$	386,297	$	25,354	$	6,573,656	$	1,052,185	$	850,207
Reinsurance & Monoline Excess	886,200		139,768		—		1,025,968		209,366		167,329
Corporate, other and eliminations (3)	—		21,837		403,937		425,774		(147,590)		(119,530)
Net investment gains	—		—		127,299		127,299		127,299		100,833
Total	$	7,048,205	$	547,902	$	556,590	$	8,152,697	$	1,241,260	$	998,839

_________________

(1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions.

(2) Revenues for Insurance from foreign operations for the three months ended September 30, 2023 and 2022 were $298 million and $252 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $852 million and $750 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended September 30, 2023 and 2022 were $124 million and $117 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $333 million and $307 million, respectively.

(3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments.

Identifiable Assets

(In thousands)	September 30, 2023		December 31, 2022
Insurance	$	28,862,050	$	27,012,479
Reinsurance & Monoline Excess	5,194,783		5,195,752
Corporate, other and eliminations	2,054,515		1,606,872
Consolidated	$	36,111,348	$	33,815,103

    Net premiums earned by major line of business are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Insurance:
Other liability	$	918,054	$	824,595	$	2,668,831	$	2,363,349
Short-tail lines (1)	490,598		407,211		1,383,654		1,184,191
Commercial automobile	335,572		307,754		965,416		891,729
Workers' compensation	300,694		307,323		905,405		892,390
Professional liability	274,517		282,131		824,398		830,346
Total Insurance	2,319,435		2,129,014		6,747,704		6,162,005
Reinsurance & Monoline Excess:
Casualty reinsurance	192,071		193,726		574,660		568,507
Monoline excess (2)	60,363		54,675		177,853		161,181
Property reinsurance	70,045		64,546		185,856		156,512
Total Reinsurance & Monoline Excess	322,479		312,947		938,369		886,200
Total	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205

______________

(1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

(2) Monoline excess includes operations that solely retain risk on an excess basis.

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Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss) to Common Stockholders	$ 333,586	$ 228,879	$ 984,020	$ 998,839

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Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

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Recent Accounting Pronouncements and Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Per Share Data

Per Share Data

    The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 11,416,856 and 11,592,699 common shares held in a grantor trust as of September 30, 2023 and 2022, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.

    The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:

	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(In thousands)	2023	2022	2023	2022
Basic	269,191	277,192	271,656	276,928
Diluted	271,439	279,642	274,146	279,644

Recent Accounting Pronouncements

Recent Accounting Pronouncements and Accounting Policies

Recently adopted accounting pronouncements:

    All accounting and reporting standards that became effective in 2023 were either not applicable to the Company or their adoption did not have a material impact on the Company.

Accounting and reporting standards that are not yet effective:

    All recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

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Consolidated Statements of Comprehensive (Loss) Income (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Components of changes in accumulated other comprehensive income (loss)

The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"):

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(892,905)		$	(371,676)	$	(1,264,581)
Other comprehensive loss before reclassifications	(103,087)			(7,387)		(110,474)
Amounts reclassified from AOCI	52,237			—		52,237
Other comprehensive loss	(50,850)			(7,387)		(58,237)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	66,123	(1)	$	—	$	66,123
Tax effect	(13,886)		(2)	—		(13,886)
After-tax amounts reclassified	$	52,237		$	—	$	52,237
Other comprehensive loss
Pre-tax	$	(62,476)		$	(7,387)	$	(69,863)
Tax effect	11,626			—		11,626
Other comprehensive loss	$	(50,850)		$	(7,387)	$	(58,237)
As of and for the three months ended September 30, 2023
Changes in AOCI
Beginning of period	$	(825,391)		$	(356,282)	$	(1,181,673)
Other comprehensive loss before reclassifications	(133,018)			(22,781)		(155,799)
Amounts reclassified from AOCI	14,653			—		14,653
Other comprehensive loss	(118,365)			(22,781)		(141,146)
Unrealized investment loss related to noncontrolling interest	—			—		—
Ending balance	$	(943,756)		$	(379,063)	$	(1,322,819)
Amounts reclassified from AOCI
Pre-tax	$	18,548	(1)	$	—	$	18,548
Tax effect	(3,895)		(2)	—		(3,895)
After-tax amounts reclassified	$	14,653		$	—	$	14,653
Other comprehensive loss
Pre-tax	$	(150,455)		$	(22,781)	$	(173,236)
Tax effect	32,090			—		32,090
Other comprehensive loss	$	(118,365)		$	(22,781)	$	(141,146)

(In thousands)	Unrealized Investment (Losses) Gains			Currency Translation Adjustments		Accumulated Other Comprehensive (Loss) Income
As of and for the nine months ended September 30, 2022
Changes in AOCI
Beginning of period	$	90,900		$	(372,855)	$	(281,955)
Other comprehensive loss before reclassifications	(1,134,657)			(27,637)		(1,162,294)
Amounts reclassified from AOCI	58,440			—		58,440
Other comprehensive loss	(1,076,217)			(27,637)		(1,103,854)
Unrealized investment loss related to noncontrolling interest	(1)			—		(1)
End of period	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	73,975	(1)	$	—	$	73,975
Tax effect	(15,535)		(2)	—		(15,535)
After-tax amounts reclassified	$	58,440		$	—	$	58,440
Other comprehensive loss
Pre-tax	$	(1,365,064)		$	(27,637)	$	(1,392,701)
Tax effect	288,847			—		288,847
Other comprehensive loss	$	(1,076,217)		$	(27,637)	$	(1,103,854)
As of and for the three months ended September 30, 2022
Changes in AOCI
Beginning of period	$	(669,654)		$	(359,976)	$	(1,029,630)
Other comprehensive loss before reclassifications	(335,034)			(40,516)		(375,550)
Amounts reclassified from AOCI	19,370			—		19,370
Other comprehensive loss	(315,664)			(40,516)		(356,180)
Unrealized investment loss related to noncontrolling interest	—					—
Ending balance	$	(985,318)		$	(400,492)	$	(1,385,810)
Amounts reclassified from AOCI
Pre-tax	$	24,519	(1)	$	—	$	24,519
Tax effect	(5,149)		(2)	—		(5,149)
After-tax amounts reclassified	$	19,370		$	—	$	19,370
Other comprehensive loss
Pre-tax	$	(394,832)		$	(40,516)	$	(435,348)
Tax effect	79,168			—		79,168
Other comprehensive loss	$	(315,664)		$	(40,516)	$	(356,180)

____________

(1) Net investment (losses) gains in the consolidated statements of income.

(2) Income tax expense in the consolidated statements of income.

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Per Share Data (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Weighted average number of common shares

The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:

	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(In thousands)	2023	2022	2023	2022
Basic	269,191	277,192	271,656	276,928
Diluted	271,439	279,642	274,146	279,644

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Investments in Fixed Maturity Securities (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of investments in fixed maturity securities

At September 30, 2023 and December 31, 2022, investments in fixed maturity securities were as follows:

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
September 30, 2023
Held to maturity:
State and municipal	$	49,847	$	(48)	$	1,825	$	—	$	51,624	$	49,799
Residential mortgage-backed	3,029		—		19		—		3,048		3,029
Total held to maturity	52,876		(48)		1,844		—		54,672		52,828
Available for sale:
U.S. government and government agency	1,546,889		—		2,077		(81,767)		1,467,199		1,467,199
State and municipal:
Special revenue	1,771,219		—		2,287		(126,585)		1,646,921		1,646,921
State general obligation	378,650		—		1,247		(23,727)		356,170		356,170
Pre-refunded	103,219		—		202		(827)		102,594		102,594
Corporate backed	194,976		(821)		159		(14,341)		179,973		179,973
Local general obligation	401,286		—		1,767		(17,713)		385,340		385,340
Total state and municipal	2,849,350		(821)		5,662		(183,193)		2,670,998		2,670,998
Mortgage-backed:
Residential	1,660,790		(24)		399		(214,381)		1,446,784		1,446,784
Commercial	651,966		(2,076)		11		(20,389)		629,512		629,512
Total mortgage-backed	2,312,756		(2,100)		410		(234,770)		2,076,296		2,076,296
Asset-backed	4,197,235		(1,502)		750		(109,025)		4,087,458		4,087,458
Corporate:
Industrial	3,567,020		—		5,026		(227,479)		3,344,567		3,344,567
Financial	2,813,603		(5,406)		1,362		(130,312)		2,679,247		2,679,247
Utilities	683,468		(364)		164		(39,991)		643,277		643,277
Other	593,466		—		134		(11,877)		581,723		581,723
Total corporate	7,657,557		(5,770)		6,686		(409,659)		7,248,814		7,248,814
Foreign government	1,616,110		(36,171)		1,361		(149,588)		1,431,712		1,431,712
Total available for sale	20,179,897		(46,364)		16,946		(1,168,002)		18,982,477		18,982,477
Total investments in fixed maturity securities	$	20,232,773	$	(46,412)	$	18,790	$	(1,168,002)	$	19,037,149	$	19,035,305

____________

(1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors.

(In thousands)	Amortized Cost		Allowance for Expected Credit Losses (1)		Gross Unrealized				Fair Value		Carrying Value
					Gains		Losses
December 31, 2022
Held to maturity:
State and municipal	$	47,802	$	(114)	$	4,239	$	—	$	51,927	$	47,688
Residential mortgage-backed	3,608		—		38		—		3,646		3,608
Total held to maturity	51,410		(114)		4,277		—		55,573		51,296
Available for sale:
U.S. government and government agency	960,479		—		937		(69,158)		892,258		892,258
State and municipal:
Special revenue	1,837,309		—		3,662		(119,474)		1,721,497		1,721,497
State general obligation	387,709		—		2,651		(21,335)		369,025		369,025
Pre-refunded	156,106		—		2,741		(7)		158,840		158,840
Corporate backed	210,228		—		334		(10,923)		199,639		199,639
Local general obligation	454,983		—		2,967		(16,853)		441,097		441,097
Total state and municipal	3,046,335		—		12,355		(168,592)		2,890,098		2,890,098
Mortgage-backed:
Residential	1,308,019		(18)		395		(171,595)		1,136,801		1,136,801
Commercial	547,757		—		215		(19,363)		528,609		528,609
Total mortgage-backed securities	1,855,776		(18)		610		(190,958)		1,665,410		1,665,410
Asset-backed	4,132,365		—		2,730		(152,322)		3,982,773		3,982,773
Corporate:
Industrial	3,491,645		(1,704)		4,439		(241,381)		3,252,999		3,252,999
Financial	2,585,247		(2,997)		5,505		(117,383)		2,470,372		2,470,372
Utilities	586,066		—		1,307		(36,325)		551,048		551,048
Other	441,230		—		—		(11,657)		429,573		429,573
Total corporate	7,104,188		(4,701)		11,251		(406,746)		6,703,992		6,703,992
Foreign government	1,564,930		(32,633)		4,283		(135,058)		1,401,522		1,401,522
Total available for sale	18,664,073		(37,352)		32,166		(1,122,834)		17,536,053		17,536,053
Total investments in fixed maturity securities	$	18,715,483	$	(37,466)	$	36,443	$	(1,122,834)	$	17,591,626	$	17,587,349

Debt Securities, Held-to-maturity, Allowance for Credit Loss

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	114	$	387
Provision for expected credit losses	(66)		(266)
Allowance for expected credit losses, end of period	$	48	$	121

The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	53	$	127
Provision for expected credit losses	(5)		(6)
Allowance for expected credit losses, end of period	$	48	$	121

Debt Securities, Available-for-sale, Allowance for Credit Loss

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	32,633	$	4,701	$	18	$	—	$	—	$	37,352	$	22,222	$	16	$	—	$	22,238
Expected credit losses on securities for which credit losses were not previously recorded	—		942		1,766		1,444		821		4,973		1,897		1,205		21		3,123
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,538		134		316		58		—		4,046		9,289		(22)		—		9,267
Reduction due to disposals	—		(7)		—		—		—		(7)		(33)		—		—		(33)
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. During the nine months ended September 30, 2022, the Company increased the allowance for expected credit losses for available for sale securities mainly due to an increase in unrealized losses primarily associated with foreign government securities.

The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2023 and 2022:

	2023												2022
(In thousands)	Foreign Government		Corporate		Mortgage-backed		Asset-backed		State and Municipal		Total		Foreign Government		Corporate		Mortgage-backed		Total
Allowance for expected credit losses, beginning of period	$	33,052	$	8,867	$	885	$	1,444	$	—	$	44,248	$	33,096	$	182	$	—	$	33,278
Expected credit losses on securities for which credit losses were not previously recorded	—		756		905		—		821		2,482		—		1,023		21		1,044
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,119		(3,853)		310		58		—		(366)		279		(6)		—		273
Allowance for expected credit losses, end of period	$	36,171	$	5,770	$	2,100	$	1,502	$	821	$	46,364	$	33,375	$	1,199	$	21	$	34,595

Amortized cost and fair value of fixed maturity securities by contractual maturity

The amortized cost and fair value of fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  

(In thousands)	Amortized Cost (1)		Fair Value
Due in one year or less	$	1,818,820	$	1,742,384
Due after one year through five years	9,180,726		8,704,308
Due after five years through ten years	4,308,202		4,074,956
Due after ten years	2,609,192		2,436,157
Mortgage-backed securities	2,315,785		2,079,344
Total	$	20,232,725	$	19,037,149

________________

(1) Amortized cost is reduced by the allowance for expected credit losses of $48 thousand related to held to maturity securities.

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Investments in Equity Securities (Tables)

9 Months Ended

Sep. 30, 2023

Equity securities

Debt Securities, Available-for-sale [Line Items]

Schedule of Investments in Equity Securities

At September 30, 2023 and December 31, 2022, investments in equity securities were as follows:

(In thousands)	Cost		Gross Unrealized				Fair Value		Carrying Value
			Gains		Losses
September 30, 2023
Common stocks	$	792,512	$	209,979	$	(41,058)	$	961,433	$	961,433
Preferred stocks	273,376		2,383		(55,131)		220,628		220,628
Total	$	1,065,888	$	212,362	$	(96,189)	$	1,182,061	$	1,182,061
December 31, 2022
Common stocks	$	855,987	$	192,165	$	(65,401)	$	982,751	$	982,751
Preferred stocks	259,341		1,053		(57,251)		203,143		203,143
Total	$	1,115,328	$	193,218	$	(122,652)	$	1,185,894	$	1,185,894

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Net Investment Income (Tables)

9 Months Ended

Sep. 30, 2023

Net Investment Income [Abstract]

Schedule of Net Investment Income

Net investment income consisted of the following: 

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Investment income (loss) earned on:
Fixed maturity securities, including cash and cash equivalents and loans receivable	$	239,727	$	146,051	$	653,200	$	371,724
Arbitrage trading account (1)	17,876		10,694		53,168		24,008
Equity securities	12,714		14,650		41,714		38,303
Investment funds	4,450		36,045		5,444		121,919
Real estate	(1,986)		(2,297)		(7,821)		(1,702)
Gross investment income	272,781		205,143		745,705		554,252
Investment expense	(1,837)		(2,327)		(6,211)		(6,350)
Net investment income	$	270,944	$	202,816	$	739,494	$	547,902

(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.

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Investment Funds (Tables)

9 Months Ended

Sep. 30, 2023

Equity Method Investments and Joint Ventures [Abstract]

Schedule of Investment Funds

Investment funds consisted of the following:

	Carrying Value as of				Income (Loss) from Investment Funds
	September 30,		December 31,		For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Financial services	$	429,889	$	465,683	$	(15,606)	$	27,472
Transportation	336,020		336,753		37,894		48,249
Real Estate	191,445		204,644		(5,062)		42,708
Infrastructure	124,528		115,428		7,813		1,277
Energy	115,349		116,432		3,921		1,966
Other funds	403,264		369,608		(23,516)		247
Total	$	1,600,495	$	1,608,548	$	5,444	$	121,919

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Real Estate (Tables)

9 Months Ended

Sep. 30, 2023

Real Estate [Abstract]

Schedule of Real Estate Investments

Investment in real estate represents directly owned property held for investment, as follows:

	Carrying Value
	September 30,		December 31,
(In thousands)	2023		2022
Properties in operation	$	1,043,419	$	1,114,167
Properties under development	227,126		226,455
Total	$	1,270,545	$	1,340,622

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Loans Receivable Loans Receivable (Tables)

9 Months Ended

Sep. 30, 2023

Receivables [Abstract]

Schedule of Loans Receivable

At September 30, 2023 and December 31, 2022, loans receivable were as follows:

(In thousands)	September 30, 2023		December 31, 2022
Amortized cost (net of allowance for expected credit losses):
Real estate loans	$	159,857	$	173,616
Commercial loans	17,893		19,386
Total	$	177,750	$	193,002
Fair value:
Real estate loans	$	156,407	$	168,595
Commercial loans	17,893		19,386
Total	$	174,300	$	187,981

Financing Receivable, Allowance for Credit Loss

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the nine months ended September 30, 2023 and 2022:

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	1,100	$	691	$	1,791	$	1,362	$	356	$	1,718
Change in expected credit losses	2,302		(84)		2,218		(200)		474		274
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses due to changes in economic assumptions utilized in its credit loss model. During the nine months ended September 30, 2022, the Company increased the allowance primarily due to an increase in the weighted average life of the loans receivable portfolio.

The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended September 30, 2023 and 2022:

	2023						2022
(In thousands)	Real Estate Loans		Commercial Loans		Total		Real Estate Loans		Commercial Loans		Total
Allowance for expected credit losses, beginning of period	$	3,658	$	892	$	4,550	$	1,228	$	947	$	2,175
Change in expected credit losses	(256)		(285)		(541)		(66)		(117)		(183)
Allowance for expected credit losses, end of period	$	3,402	$	607	$	4,009	$	1,162	$	830	$	1,992

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Net Investment (Losses) Gains (Tables)

9 Months Ended

Sep. 30, 2023

Realized and Unrealized Investment Gains (Losses) [Abstract]

Realized And Unrealized Investment Gains (Losses)

Net investment (losses) gains were as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Net investment (losses) gains:
Fixed maturity securities:
Gains	$	299	$	1,053	$	1,357	$	3,405
Losses	(2,700)		(2,309)		(24,470)		(8,752)
Equity securities (1):
Net realized gains on investment sales (2)	23,631		—		135,763		946
Change in unrealized (losses) gains	(19,059)		(50,384)		45,605		(88,701)
Investment funds	(3,329)		(1,717)		(3,417)		(6,241)
Real estate (3) (4)	(24,234)		9,026		(68,944)		295,576
Loans receivable	(1,428)		—		(1,428)		(32)
Other	(14,035)		(21,951)		(34,063)		(56,537)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(40,855)		(66,282)		50,403		139,664
Change in allowance for expected credit losses on investments:
Fixed maturity securities	(2,112)		(1,311)		(8,946)		(12,091)
Loans receivable	541		183		(2,218)		(274)
Change in allowance for expected credit losses on investments	(1,571)		(1,128)		(11,164)		(12,365)
Net investment (losses) gains	(42,426)		(67,410)		39,239		127,299
Income tax benefit (expense)	9,405		14,456		(8,033)		(26,466)
After-tax net investment (losses) gains	$	(33,021)	$	(52,954)	$	31,206	$	100,833

Change in unrealized investment (losses) gains on available for sale securities:
Fixed maturity securities without allowance for expected credit losses	$	(136,388)	$	(385,503)	$	(57,293)	$	(1,335,413)
Fixed maturity securities with allowance for expected credit losses	(10,244)		(4,005)		(3,094)		(20,590)
Investment funds	(3,217)		(5,031)		(818)		(7,863)
Other	(606)		(293)		(1,271)		(1,198)
Total change in unrealized investment losses	(150,455)		(394,832)		(62,476)		(1,365,064)
Income tax benefit	32,090		79,168		11,626		288,847
Noncontrolling interests	—		—		(1)		(1)
After-tax change in unrealized investment losses of available for sale securities	$	(118,365)	$	(315,664)	$	(50,851)	$	(1,076,218)

______________________

(1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized (losses) gains consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held.

(2) In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million on the sale (proceeds from the sale is presented on the business disposition line within the Consolidated Statements of Cash Flows).

(3) The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

(4) During March 2022, the Company realized a gain on the sale of a real estate investment in London, U.K. of $251 million, net of transaction expenses and the foreign currency impact, including the reversal of the currency translation adjustment.

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Fixed Maturity Securities In An Unrealized Loss Position (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Securities in an unrealized loss position

The following tables summarize all fixed maturity securities in an unrealized loss position at September 30, 2023 and December 31, 2022 by the length of time those securities have been continuously in an unrealized loss position:

	Less Than 12 Months				12 Months or Greater				Total
(In thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
September 30, 2023
U.S. government and government agency	$	605,944	$	17,390	$	592,215	$	64,377	$	1,198,159	$	81,767
State and municipal	645,642		15,255		1,728,892		167,938		2,374,534		183,193
Mortgage-backed	688,848		17,058		1,296,384		217,712		1,985,232		234,770
Asset-backed	1,025,656		8,774		2,584,224		100,251		3,609,880		109,025
Corporate	2,091,830		46,758		4,695,101		362,901		6,786,931		409,659
Foreign government	563,657		15,038		779,455		134,550		1,343,112		149,588
Fixed maturity securities	$	5,621,577	$	120,273	$	11,676,271	$	1,047,729	$	17,297,848	$	1,168,002
December 31, 2022
U.S. government and government agency	$	285,391	$	10,219	$	453,520	$	58,939	$	738,911	$	69,158
State and municipal	1,720,443		89,272		598,797		79,320		2,319,240		168,592
Mortgage-backed	1,099,549		75,430		473,318		115,528		1,572,867		190,958
Asset-backed	1,569,647		48,390		2,176,638		103,932		3,746,285		152,322
Corporate	3,690,856		150,115		2,349,281		256,631		6,040,137		406,746
Foreign government	477,672		29,815		711,786		105,243		1,189,458		135,058
Fixed maturity securities	$	8,843,558	$	403,241	$	6,763,340	$	719,593	$	15,606,898	$	1,122,834

Non-Investment Grade Fixed Maturity Securities

A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2023 is presented in the table below:

($ in thousands)	Number of Securities	Aggregate Fair Value		Gross Unrealized Loss
Foreign government	44	$	88,668	$	91,468
Corporate	26	35,644		3,523
State and municipal	5	22,866		6,374
Mortgage-backed	15	4,328		214
Asset-backed	5	244		107
Total	95	$	151,750	$	101,686

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Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Assets And Liabilities Measured At Fair value, On A Recurring Basis

The following tables present the assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 by level:

(In thousands)	Total		Level 1		Level 2		Level 3
September 30, 2023
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	1,467,199	$	—	$	1,467,199	$	—
State and municipal	2,670,998		—		2,670,998		—
Mortgage-backed	2,076,296		—		2,076,296		—
Asset-backed	4,087,458		—		4,087,458		—
Corporate	7,248,814		—		7,248,814		—
Foreign government	1,431,712		—		1,431,712		—
Total fixed maturity securities available for sale	18,982,477		—		18,982,477		—
Equity securities:
Common stocks	961,433		958,202		1,060		2,171
Preferred stocks	220,628		—		216,930		3,698
Total equity securities	1,182,061		958,202		217,990		5,869
Arbitrage trading account	825,049		614,995		206,536		3,518
Total	$	20,989,587	$	1,573,197	$	19,407,003	$	9,387
Liabilities:
Trading account securities sold but not yet purchased	$	7,538	$	7,538	$	—	$	—
December 31, 2022
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency	$	892,258	$	—	$	892,258	$	—
State and municipal	2,890,098		—		2,890,098		—
Mortgage-backed	1,665,410		—		1,665,410		—
Asset-backed	3,982,773		—		3,982,773		—
Corporate	6,703,992		—		6,703,992		—
Foreign government	1,401,522		—		1,401,522		—
Total fixed maturity securities available for sale	17,536,053		—		17,536,053		—
Equity securities:
Common stocks	982,751		978,991		1,161		2,599
Preferred stocks	203,143		—		191,844		11,299
Total equity securities	1,185,894		978,991		193,005		13,898
Arbitrage trading account	944,230		822,192		118,448		3,590
Total	$	19,666,177	$	1,801,183	$	17,847,506	$	17,488
Liabilities:
Trading account securities sold but not yet purchased	$	—	$	—	$	—	$	—

Summarize Changes In Level 3 Assets

The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2023 and for the year ended December 31, 2022:

Gains (Losses) Included In:
(In thousands)	Beginning Balance		Earnings (Losses)		Other Comprehensive Income (Losses)		Impairments		Purchases		Sales		Paydowns / Maturities		Transfers In / (Out)		Ending Balance
Nine Months Ended September 30, 2023
Assets:
Equity securities:
Common stocks	$	2,599	$	(428)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,171
Preferred stocks	11,299		—		—		(7,601)		—		—		—		—		3,698
Total	13,898		(428)		—		(7,601)		—		—		—		—		5,869
Arbitrage trading account	3,590		(72)		—		—		—		—		—		—		3,518
Total	$	17,488	$	(500)	$	—	$	(7,601)	$	—	$	—	$	—	$	—	$	9,387
Year Ended December 31, 2022
Assets:
Equity securities:
Common stocks	$	9,294	$	(6,695)	$	—	$	—	$	—	$	—	$	—	$	—	$	2,599
Preferred stocks	11,296		3		—		—		925		(925)		—		—		11,299
Total	20,590		(6,692)		—		—		925		(925)		—		—		13,898
Arbitrage trading account	—		(179)		—		—		4,686		(917)		—		—		3,590
Total	$	20,590	$	(6,871)	$	—	$	—	$	5,611	$	(1,842)	$	—	$	—	$	17,488

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Reserves for Loss and Loss Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Reserve Balances

The table below provides a reconciliation of the beginning and ending reserve balances:

	September 30,
(In thousands)	2023		2022
Net reserves at beginning of period	$	14,248,879	$	12,848,362
Net provision for losses and loss expenses:
Claims occurring during the current year (1)	4,694,554		4,260,179
Increase in estimates for claims occurring in prior years (2) (3)	27,186		54,632
Loss reserve discount accretion	22,862		24,835
Total	4,744,602		4,339,646
Net payments for claims:
Current year	743,416		643,908
Prior years	2,915,979		2,499,319
Total	3,659,395		3,143,227
Foreign currency translation	(48,162)		(193,755)
Net reserves at end of period	15,285,924		13,851,026
Ceded reserves at end of period	2,987,386		2,689,097
Gross reserves at end of period	$	18,273,310	$	16,540,123

_______________________________________

(1) Claims occurring during the current year are net of loss reserve discounts of $35 million and $26 million for the nine months ended September 30, 2023 and 2022, respectively.

(2) The change in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $12 million and increased by $20 million for the nine months ended September 30, 2023 and 2022, respectively.

(3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Adverse development, net of additional and return premiums, was $20 million and $37 million for the nine months ended September 30, 2023 and 2022, respectively.

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Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Carrying Amounts And Estimated Fair Values Of Financial Instruments

The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:

	September 30, 2023				December 31, 2022
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets:
Fixed maturity securities	$	19,035,305	$	19,037,149	$	17,587,349	$	17,591,626
Equity securities	1,182,061		1,182,061		1,185,894		1,185,894
Arbitrage trading account	825,049		825,049		944,230		944,230
Loans receivable	177,750		174,300		193,002		187,981
Cash and cash equivalents	1,646,074		1,646,074		1,449,346		1,449,346
Trading account receivables from brokers and clearing organizations	401,982		401,982		233,863		233,863
Due from broker	—		—		3,609		3,609
Liabilities:
Due to broker	5,118		5,118		—		—
Trading account securities sold but not yet purchased	7,538		7,538		—		—
Senior notes and other debt	1,828,046		1,321,014		1,828,823		1,439,188
Subordinated debentures	1,008,910		786,798		1,008,371		805,600

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Premiums and Reinsurance Related Information (Tables)

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Reinsurance Financial Information

The following is a summary of insurance and reinsurance financial information:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Written premiums:
Direct	$	3,037,932	$	2,775,236	$	8,762,249	$	8,075,311
Assumed	315,273		306,702		977,047		918,864
Ceded	(504,746)		(504,664)		(1,504,497)		(1,418,012)
Total net premiums written	$	2,848,459	$	2,577,274	$	8,234,799	$	7,576,163
Earned premiums:
Direct	$	2,825,176	$	2,617,680	$	8,217,888	$	7,533,856
Assumed	316,134		318,962		913,795		903,882
Ceded	(499,396)		(494,681)		(1,445,610)		(1,389,533)
Total net premiums earned	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205
Ceded losses and loss expenses incurred	$	320,995	$	347,439	$	970,267	$	905,667
Ceded commissions earned	$	118,207	$	121,721	$	354,148	$	356,157

Premium receivable, allowance for credit loss

The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	30,660	$	25,218
Change in expected credit losses	2,942		5,360
Allowance for expected credit losses, end of period	$	33,602	$	30,578

The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	32,770	$	30,557
Change in expected credit losses	832		21
Allowance for expected credit losses, end of period	$	33,602	$	30,578

Reinsurance Recoverable, Allowance for Credit Loss

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the nine months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	8,064	$	7,713
Change in expected credit losses	1,379		286
Allowance for expected credit losses, end of period	$	9,443	$	7,999

The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended September 30, 2023 and 2022:

(In thousands)	2023		2022
Allowance for expected credit losses, beginning of period	$	9,365	$	7,744
Change in expected credit losses	78		255
Allowance for expected credit losses, end of period	$	9,443	$	7,999

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Restricted Stock Units (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary Of Restricted Stock Units Issued

A summary of RSUs issued in the nine months ended September 30, 2023 and 2022 follows:

($ in thousands)	Units	Fair Value
2023	1,092,130	$	68,936
2022	1,023,871	$	67,345

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Leases (Tables)

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Lease, Cost

Further information relating to operating lease expense and other operating lease information are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Leases:
Lease cost	$	10,122	$	11,299	$	30,448	$	33,649
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	$	11,403	$	11,082	$	33,247	$	33,128
Right-of-use assets obtained in exchange for new lease liabilities	$	6,543	$	1,527	$	14,489	$	21,729

Supplemental Balance Sheet Information

	As of September 30,
($ in thousands)	2023			2022
Right-of-use assets	$	155,662		$	163,940
Lease liabilities	$	188,141		$	199,889
Weighted-average remaining lease term	6.9 years			7.1 years
Weighted-average discount rate	4.55		%	4.50		%

Maturities of Operating Lease Liabilities

Contractual maturities of the Company’s future minimum lease payments are as follows:

(In thousands)	September 30, 2023
Contractual Maturities:
2023	$	12,171
2024	44,531
2025	36,167
2026	28,933
2027	19,144
Thereafter	74,394
Total undiscounted future minimum lease payments	215,340
Less: Discount impact	27,199
Total lease liability	$	188,141

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Business Segments (Tables)

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Financial Information Of Company Operating Segments

	Revenues
(In thousands)	Earned Premiums (1)		Investment Income		Other		Total (2)		Pre-Tax Income (Loss)		Net Income (Loss) to Common Stockholders
Three months ended September 30, 2023
Insurance	$	2,319,435	$	206,792	$	9,143	$	2,535,370	$	415,279	$	329,519
Reinsurance & Monoline Excess	322,479		56,259		—		378,738		106,072		83,314
Corporate, other and eliminations (3)	—		7,893		151,063		158,956		(58,976)		(46,226)
Net investment losses	—		—		(42,426)		(42,426)		(42,426)		(33,021)
Total	$	2,641,914	$	270,944	$	117,780	$	3,030,638	$	419,949	$	333,586
Three months ended September 30, 2022
Insurance	$	2,129,014	$	134,519	$	8,341	$	2,271,874	$	322,312	$	258,521
Reinsurance & Monoline Excess	312,947		55,234		—		368,181		59,561		46,875
Corporate, other and eliminations (3)	—		13,063		138,692		151,755		(28,198)		(23,563)
Net investment losses	—		—		(67,410)		(67,410)		(67,410)		(52,954)
Total	$	2,441,961	$	202,816	$	79,623	$	2,724,400	$	286,265	$	228,879
Nine months ended September 30, 2023
Insurance	$	6,747,704	$	560,182	$	27,570	$	7,335,456	$	1,153,742	$	903,575
Reinsurance & Monoline Excess	938,369		148,525		—		1,086,894		313,290		248,279
Corporate, other and eliminations (3)	—		30,787		429,180		459,967		(253,066)		(199,040)
Net investment gains	—		—		39,239		39,239		39,239		31,206
Total	$	7,686,073	$	739,494	$	495,989	$	8,921,556	$	1,253,205	$	984,020
Nine months ended September 30, 2022
Insurance	$	6,162,005	$	386,297	$	25,354	$	6,573,656	$	1,052,185	$	850,207
Reinsurance & Monoline Excess	886,200		139,768		—		1,025,968		209,366		167,329
Corporate, other and eliminations (3)	—		21,837		403,937		425,774		(147,590)		(119,530)
Net investment gains	—		—		127,299		127,299		127,299		100,833
Total	$	7,048,205	$	547,902	$	556,590	$	8,152,697	$	1,241,260	$	998,839

_________________

(1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions.

(2) Revenues for Insurance from foreign operations for the three months ended September 30, 2023 and 2022 were $298 million and $252 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $852 million and $750 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended September 30, 2023 and 2022 were $124 million and $117 million, respectively, and for the nine months ended September 30, 2023 and 2022 were $333 million and $307 million, respectively.(3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments

Identifiable Assets By Segment

(In thousands)	September 30, 2023		December 31, 2022
Insurance	$	28,862,050	$	27,012,479
Reinsurance & Monoline Excess	5,194,783		5,195,752
Corporate, other and eliminations	2,054,515		1,606,872
Consolidated	$	36,111,348	$	33,815,103

Net Premiums Earned By Major Line Of Business

Net premiums earned by major line of business are as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Insurance:
Other liability	$	918,054	$	824,595	$	2,668,831	$	2,363,349
Short-tail lines (1)	490,598		407,211		1,383,654		1,184,191
Commercial automobile	335,572		307,754		965,416		891,729
Workers' compensation	300,694		307,323		905,405		892,390
Professional liability	274,517		282,131		824,398		830,346
Total Insurance	2,319,435		2,129,014		6,747,704		6,162,005
Reinsurance & Monoline Excess:
Casualty reinsurance	192,071		193,726		574,660		568,507
Monoline excess (2)	60,363		54,675		177,853		161,181
Property reinsurance	70,045		64,546		185,856		156,512
Total Reinsurance & Monoline Excess	322,479		312,947		938,369		886,200
Total	$	2,641,914	$	2,441,961	$	7,686,073	$	7,048,205

______________

(1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

(2) Monoline excess includes operations that solely retain risk on an excess basis.

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Consolidated Statements of Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 6,768,161
Other comprehensive loss	$ (141,146)	$ (356,180)	(58,237)	$ (1,103,854)
End of period	6,929,909		6,929,909
Net realized and unrealized (losses) gains on investments	(40,855)	(66,282)	50,403	139,664
Income before income taxes	419,949	286,265	1,253,205	1,241,260
Tax effect	(86,519)	(55,791)	(268,322)	(238,290)
Net income before noncontrolling interests	333,430	230,474	984,883	1,002,970
Total change in unrealized investment losses	(150,455)	(394,832)	(62,476)	(1,365,064)
Net change in period	(22,781)	(40,516)	(7,387)	(27,637)
Other comprehensive income (loss), pre-tax	(173,236)	(435,348)	(69,863)	(1,392,701)
Other comprehensive income (loss), tax effect	32,090	79,168	11,626	288,847
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(1,181,673)	(1,029,630)	(1,264,581)	(281,955)
Other comprehensive income (loss) before reclassifications	(155,799)	(375,550)	(110,474)	(1,162,294)
Amounts reclassified from AOCI	14,653	19,370	52,237	58,440
Other comprehensive loss	(141,146)	(356,180)	(58,237)	(1,103,854)
Unrealized investment loss related to noncontrolling interest	0	0	(1)	(1)
End of period	(1,322,819)	(1,385,810)	(1,322,819)	(1,385,810)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	18,548	24,519	66,123	73,975
Tax effect	(3,895)	(5,149)	(13,886)	(15,535)
Net income before noncontrolling interests	14,653	19,370	52,237	58,440
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(825,391)	(669,654)	(892,905)	90,900
Other comprehensive income (loss) before reclassifications	(133,018)	(335,034)	(103,087)	(1,134,657)
Amounts reclassified from AOCI	14,653	19,370	52,237	58,440
Other comprehensive loss	(118,365)	(315,664)	(50,850)	(1,076,217)
Unrealized investment loss related to noncontrolling interest	0	0	(1)	(1)
End of period	(943,756)	(985,318)	(943,756)	(985,318)
Total change in unrealized investment losses	(150,455)	(394,832)	(62,476)	(1,365,064)
Unrealized investment gains, tax effect	32,090	79,168	11,626	288,847
Unrealized investment gains (losses), after-tax amounts	(118,365)	(315,664)	(50,850)	(1,076,217)
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized (losses) gains on investments	18,548	24,519	66,123	73,975
Tax effect	(3,895)	(5,149)	(13,886)	(15,535)
Net income before noncontrolling interests	14,653	19,370	52,237	58,440
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(356,282)	(359,976)	(371,676)	(372,855)
Other comprehensive income (loss) before reclassifications	(22,781)	(40,516)	(7,387)	(27,637)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive loss	(22,781)	(40,516)	(7,387)	(27,637)
Unrealized investment loss related to noncontrolling interest	0		0	0
End of period	(379,063)	(400,492)	(379,063)	(400,492)
Currency translation adjustment, pre-tax	(22,781)	(40,516)	(7,387)	(27,637)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	(22,781)	(40,516)	(7,387)	(27,637)
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0	0	0
Tax effect	0	0	0	0
Net income before noncontrolling interests	$ 0	$ 0	$ 0	$ 0

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Statements of Cash Flows (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 79,336,000	$ 115,756,000
Income taxes paid	$ 180,000,000	$ 263,971,000

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Per Share Data (Narrative) (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust (in shares)	11,416,856,000	11,592,699

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Per Share Data (Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Basic (shares)	269,191	277,192	271,656	276,928
Diluted (shares)	271,439	279,642	274,146	279,644

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Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	$ 52,876		$ 51,410
Held-to-maturity, Allowance for Credit Loss	(48)	$ (53)	(114)	$ (121)	$ (127)	$ (387)
Held to maturity, Gross Unrealized Gains	1,844		4,277
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	54,672		55,573
Total held to maturity, Carrying Value	52,828		51,296
Total available for sale, Amortized Cost	20,179,897		18,664,073
Available-for-sale, Allowance for Credit Loss	(46,364)	(44,248)	(37,352)	(34,595)	(33,278)	(22,238)
Total available for sale, Gross Unrealized Gains	16,946		32,166
Total available for sale, Gross Unrealized Losses	(1,168,002)		(1,122,834)
Total available for sale, Fair Value	18,982,477		17,536,053
Total fixed maturity securities available for sale	18,982,477		17,536,053
Total investments in fixed maturity securities, Amortized Value	20,232,773		18,715,483
Fixed maturity securities, allowance for credit loss	(46,412)		(37,466)
Total investments in fixed maturity securities, Gross Unrealized Gains	18,790		36,443
Total investments in fixed maturity securities, Gross Unrealized Losses	(1,168,002)		(1,122,834)
Total investments in fixed maturity securities, Fair Value	19,037,149		17,591,626
Total investments in fixed maturity securities, Carrying Value	19,035,305		17,587,349
State and municipal
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	49,847		47,802
Held-to-maturity, Allowance for Credit Loss	(48)		(114)
Held to maturity, Gross Unrealized Gains	1,825		4,239
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	51,624		51,927
Total held to maturity, Carrying Value	49,799		47,688
Total available for sale, Amortized Cost	2,849,350		3,046,335
Available-for-sale, Allowance for Credit Loss	(821)	0	0
Total available for sale, Gross Unrealized Gains	5,662		12,355
Total available for sale, Gross Unrealized Losses	(183,193)		(168,592)
Total available for sale, Fair Value	2,670,998		2,890,098
Total fixed maturity securities available for sale	2,670,998		2,890,098
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	3,029		3,608
Held-to-maturity, Allowance for Credit Loss	0		0
Held to maturity, Gross Unrealized Gains	19		38
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	3,048		3,646
Total held to maturity, Carrying Value	3,029		3,608
Total available for sale, Amortized Cost	1,660,790		1,308,019
Available-for-sale, Allowance for Credit Loss	(24)		(18)
Total available for sale, Gross Unrealized Gains	399		395
Total available for sale, Gross Unrealized Losses	(214,381)		(171,595)
Total available for sale, Fair Value	1,446,784		1,136,801
Total fixed maturity securities available for sale	1,446,784		1,136,801
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,546,889		960,479
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	2,077		937
Total available for sale, Gross Unrealized Losses	(81,767)		(69,158)
Total available for sale, Fair Value	1,467,199		892,258
Total fixed maturity securities available for sale	1,467,199		892,258
Special revenue
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,771,219		1,837,309
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	2,287		3,662
Total available for sale, Gross Unrealized Losses	(126,585)		(119,474)
Total available for sale, Fair Value	1,646,921		1,721,497
Total fixed maturity securities available for sale	1,646,921		1,721,497
State general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	378,650		387,709
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	1,247		2,651
Total available for sale, Gross Unrealized Losses	(23,727)		(21,335)
Total available for sale, Fair Value	356,170		369,025
Total fixed maturity securities available for sale	356,170		369,025
Pre-refunded
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	103,219		156,106
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	202		2,741
Total available for sale, Gross Unrealized Losses	(827)		(7)
Total available for sale, Fair Value	102,594		158,840
Total fixed maturity securities available for sale	102,594		158,840
Corporate backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	194,976		210,228
Available-for-sale, Allowance for Credit Loss	(821)		0
Total available for sale, Gross Unrealized Gains	159		334
Total available for sale, Gross Unrealized Losses	(14,341)		(10,923)
Total available for sale, Fair Value	179,973		199,639
Total fixed maturity securities available for sale	179,973		199,639
Local general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	401,286		454,983
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	1,767		2,967
Total available for sale, Gross Unrealized Losses	(17,713)		(16,853)
Total available for sale, Fair Value	385,340		441,097
Total fixed maturity securities available for sale	385,340		441,097
Commercial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	651,966		547,757
Available-for-sale, Allowance for Credit Loss	(2,076)		0
Total available for sale, Gross Unrealized Gains	11		215
Total available for sale, Gross Unrealized Losses	(20,389)		(19,363)
Total available for sale, Fair Value	629,512		528,609
Total fixed maturity securities available for sale	629,512		528,609
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,312,756		1,855,776
Available-for-sale, Allowance for Credit Loss	(2,100)	(885)	(18)	(21)	0	0
Total available for sale, Gross Unrealized Gains	410		610
Total available for sale, Gross Unrealized Losses	(234,770)		(190,958)
Total available for sale, Fair Value	2,076,296		1,665,410
Total fixed maturity securities available for sale	2,076,296		1,665,410
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	4,197,235		4,132,365
Available-for-sale, Allowance for Credit Loss	(1,502)	(1,444)	0
Total available for sale, Gross Unrealized Gains	750		2,730
Total available for sale, Gross Unrealized Losses	(109,025)		(152,322)
Total available for sale, Fair Value	4,087,458		3,982,773
Total fixed maturity securities available for sale	4,087,458		3,982,773
Industrial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,567,020		3,491,645
Available-for-sale, Allowance for Credit Loss	0		(1,704)
Total available for sale, Gross Unrealized Gains	5,026		4,439
Total available for sale, Gross Unrealized Losses	(227,479)		(241,381)
Total available for sale, Fair Value	3,344,567		3,252,999
Total fixed maturity securities available for sale	3,344,567		3,252,999
Financial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,813,603		2,585,247
Available-for-sale, Allowance for Credit Loss	(5,406)		(2,997)
Total available for sale, Gross Unrealized Gains	1,362		5,505
Total available for sale, Gross Unrealized Losses	(130,312)		(117,383)
Total available for sale, Fair Value	2,679,247		2,470,372
Total fixed maturity securities available for sale	2,679,247		2,470,372
Utilities
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	683,468		586,066
Available-for-sale, Allowance for Credit Loss	(364)		0
Total available for sale, Gross Unrealized Gains	164		1,307
Total available for sale, Gross Unrealized Losses	(39,991)		(36,325)
Total available for sale, Fair Value	643,277		551,048
Total fixed maturity securities available for sale	643,277		551,048
Other
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	593,466		441,230
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	134		0
Total available for sale, Gross Unrealized Losses	(11,877)		(11,657)
Total available for sale, Fair Value	581,723		429,573
Total fixed maturity securities available for sale	581,723		429,573
Corporate
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	7,657,557		7,104,188
Available-for-sale, Allowance for Credit Loss	(5,770)	(8,867)	(4,701)	(1,199)	(182)	(16)
Total available for sale, Gross Unrealized Gains	6,686		11,251
Total available for sale, Gross Unrealized Losses	(409,659)		(406,746)
Total available for sale, Fair Value	7,248,814		6,703,992
Total fixed maturity securities available for sale	7,248,814		6,703,992
Foreign government
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,616,110		1,564,930
Available-for-sale, Allowance for Credit Loss	(36,171)	$ (33,052)	(32,633)	$ (33,375)	$ (33,096)	$ (22,222)
Total available for sale, Gross Unrealized Gains	1,361		4,283
Total available for sale, Gross Unrealized Losses	(149,588)		(135,058)
Total available for sale, Fair Value	1,431,712		1,401,522
Total fixed maturity securities available for sale	$ 1,431,712		$ 1,401,522

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Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 53	$ 127	$ 114	$ 387
Cumulative effect adjustment resulting from changes in accounting principles	48	121	48	121
Provision for expected credit losses	(5)	(6)	(66)	(266)
Allowance for expected credit losses, end of period	$ 48	$ 121	$ 48	$ 121

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Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 44,248	$ 33,278	$ 37,352	$ 22,238
Cumulative effect adjustment resulting from changes in accounting principles	46,364	34,595	46,364	34,595
Expected credit losses on securities for which credit losses were not previously recorded	2,482	1,044	4,973	3,123
Expected credit losses (gains) on securities for which credit losses were previously recorded	(366)	273	4,046	9,267
Reduction due to disposals			(7)	(33)
Allowance for expected credit losses, end of period	46,364	34,595	46,364	34,595
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	33,052	33,096	32,633	22,222
Cumulative effect adjustment resulting from changes in accounting principles	36,171	33,375	36,171	33,375
Expected credit losses on securities for which credit losses were not previously recorded	0	0	0	1,897
Expected credit losses (gains) on securities for which credit losses were previously recorded	3,119	279	3,538	9,289
Reduction due to disposals			0	(33)
Allowance for expected credit losses, end of period	36,171	33,375	36,171	33,375
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	8,867	182	4,701	16
Cumulative effect adjustment resulting from changes in accounting principles	5,770	1,199	5,770	1,199
Expected credit losses on securities for which credit losses were not previously recorded	756	1,023	942	1,205
Expected credit losses (gains) on securities for which credit losses were previously recorded	(3,853)	(6)	134	(22)
Reduction due to disposals			(7)	0
Allowance for expected credit losses, end of period	5,770	1,199	5,770	1,199
Mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	885	0	18	0
Cumulative effect adjustment resulting from changes in accounting principles	2,100	21	2,100	21
Expected credit losses on securities for which credit losses were not previously recorded	905	21	1,766	21
Expected credit losses (gains) on securities for which credit losses were previously recorded	310	0	316	0
Reduction due to disposals			0	0
Allowance for expected credit losses, end of period	2,100	$ 21	2,100	$ 21
Asset-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	1,444		0
Cumulative effect adjustment resulting from changes in accounting principles	1,502		1,502
Expected credit losses on securities for which credit losses were not previously recorded	0		1,444
Expected credit losses (gains) on securities for which credit losses were previously recorded	58		58
Reduction due to disposals			0
Allowance for expected credit losses, end of period	1,502		1,502
State and municipal
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	0		0
Cumulative effect adjustment resulting from changes in accounting principles	821		821
Expected credit losses on securities for which credit losses were not previously recorded	821		821
Expected credit losses (gains) on securities for which credit losses were previously recorded	0		0
Reduction due to disposals			0
Allowance for expected credit losses, end of period	$ 821		$ 821

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Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 1,818,820
Amortized Cost, Due after one year through five years	9,180,726
Amortized Cost, Due after five years through ten years	4,308,202
Amortized Cost, Due after ten years	2,609,192
Amortized Cost, Mortgaged-backed securities	2,315,785
Total investments in fixed maturity securities, Amortized Value	20,232,725
Fair Value, Due in one year or less	1,742,384
Fair Value, Due after one year through five years	8,704,308
Fair Value, Due after five years through ten years	4,074,956
Fair Value, Due after ten years	2,436,157
Fair Value, Mortgage-backed securities	2,079,344
Total investments in fixed maturity securities, Fair Value	19,037,149		$ 17,591,626
Cumulative effect adjustment resulting from changes in accounting principles	$ 48	$ 53	$ 114	$ 121	$ 127	$ 387

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Investments in Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Equity securities		$ 1,182,061	$ 1,185,894
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost		1,065,888	1,115,328
Gross Unrealized, Gains	$ 193,218	212,362
Gross Unrealized, Losses	(122,652)	(96,189)
Equity securities		1,182,061	1,185,894
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost		792,512	855,987
Gross Unrealized, Gains	192,165	209,979
Gross Unrealized, Losses	(65,401)	(41,058)
Equity securities		961,433	982,751
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost		273,376	259,341
Gross Unrealized, Gains	1,053	2,383
Gross Unrealized, Losses	$ (57,251)	(55,131)
Equity securities		220,628	203,143
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities		1,182,061	1,185,894
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities		961,433	982,751
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities		$ 220,628	$ 203,143

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Arbitrage Trading Account (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Arbitrage trading account	$ 825,000,000	$ 944,000,000
Long | Options held
Derivative [Line Items]
Fair value of derivative	256,000
Notional amount of derivative	50,000,000
Short | Options held
Derivative [Line Items]
Fair value of derivative	6,000,000
Notional amount of derivative	$ 50,000,000

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Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Investment Income [Line Items]
Gross investment income	$ 272,781	$ 205,143	$ 745,705	$ 554,252
Investment expense	(1,837)	(2,327)	(6,211)	(6,350)
Net investment income	270,944	202,816	739,494	547,902
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	239,727	146,051	653,200	371,724
Arbitrage trading account (1)
Net Investment Income [Line Items]
Gross investment income	4,450	36,045	5,444	121,919
Equity securities
Net Investment Income [Line Items]
Gross investment income	12,714	14,650	41,714	38,303
Investment funds
Net Investment Income [Line Items]
Gross investment income	17,876	10,694	53,168	24,008
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (1,986)	$ (2,297)	$ (7,821)	$ (1,702)

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Investment Funds (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		18 Months Ended
	Jul. 01, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Unfunded commitments		$ 353,000		$ 353,000
Investment funds		1,600,495		1,600,495			$ 1,608,548
Income (Loss) from Investment Funds				5,444	$ 121,919
Written premiums ceded		504,746	$ 504,664	1,504,497	1,418,012
Fair Value
Schedule of Equity Method Investments [Line Items]
Trading account receivables from brokers and clearing organizations		401,982		401,982			233,863
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	30.00%					22.50%
Written premiums ceded				348,000	308,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds		191,445		191,445			204,644
Income (Loss) from Investment Funds				(5,062)	42,708
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds		429,889		429,889			465,683
Income (Loss) from Investment Funds				(15,606)	27,472
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds		336,020		336,020			336,753
Income (Loss) from Investment Funds				37,894	48,249
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds		115,349		115,349			116,432
Income (Loss) from Investment Funds				3,921	1,966
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investment funds		124,528		124,528			115,428
Income (Loss) from Investment Funds				7,813	1,277
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds		403,264		403,264			369,608
Income (Loss) from Investment Funds				(23,516)	$ 247
Deferred compensation trust assets		$ 31,000		$ 31,000			$ 30,000

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Real Estate (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Real Estate [Abstract]
Properties in operation	$ 1,043,419	$ 1,114,167
Properties under development	227,126	226,455
Total	$ 1,270,545	$ 1,340,622

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Real Estate (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Real Estate [Abstract]
Accumulated depreciation and amortization on properties	$ 31,039,000	$ 31,039,000		$ 33,206,000
Real estate depreciation expense		6,667,000	$ 9,934,000
Lease future minimum payments 2021	8,368,709	8,368,709
Lease future minimum payments 2022	35,249,642	35,249,642
Lease future minimum payments 2023	34,435,718	34,435,718
Lease future minimum payments 2024	32,583,382	32,583,382
Lease future minimum payments 2025	32,074,240	32,074,240
Lease future minimum payments 2026	32,823,410	32,823,410
Real estate impairment	21,000,000	72,000,000
Lease future minimum payments there after	$ 505,344,609	$ 505,344,609

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Loans Receivable (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	$ 177,750,000	$ 193,002,000
Loans receivable	174,300,000	187,981,000
Loans in nonaccrual status	0	0
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	159,857,000	173,616,000
Loans receivable	156,407,000	168,595,000
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	17,893,000	19,386,000
Loans receivable	$ 17,893,000	$ 19,386,000
Loans receivable maturity term	10 years

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Loans Receivable - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	$ 4,550	$ 2,175	$ 1,791	$ 1,718
Change in expected credit losses	(541)	(183)	2,218	274
Allowance for expected credit losses, end of period	4,009	1,992	4,009	1,992
Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	3,658	1,228	1,100	1,362
Change in expected credit losses	(256)	(66)	2,302	(200)
Allowance for expected credit losses, end of period	3,402	1,162	3,402	1,162
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	892	947	691	356
Change in expected credit losses	(285)	(117)	(84)	474
Allowance for expected credit losses, end of period	$ 607	$ 830	$ 607	$ 830

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Net Investment (Losses) Gains (Net Investment Gains (Losses)) (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jun. 30, 2023	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gains			$ 299	$ 1,053	$ 1,357	$ 3,405
Fixed maturity securities, losses			(2,700)	(2,309)	(24,470)	(8,752)
Net realized gains on investment sales (2)			23,631	0	135,763	946
Change in unrealized (losses) gains			(19,059)	(50,384)	45,605	(88,701)
Investment funds			(3,329)	(1,717)	(3,417)	(6,241)
Real estate (3) (4)			(24,234)	9,026	(68,944)	295,576
Loans receivable			(1,428)	0	(1,428)	(32)
Other			(14,035)	(21,951)	(34,063)	(56,537)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses			(40,855)	(66,282)	50,403	139,664
Fixed maturity securities			(2,112)	(1,311)	(8,946)	(12,091)
Loans receivable			541	183	(2,218)	(274)
Change in allowance for expected credit losses on investments			(1,571)	(1,128)	(11,164)	(12,365)
Net investment (losses) gains			(42,426)	(67,410)	39,239	127,299
Income tax benefit (expense)			9,405	14,456	(8,033)	(26,466)
After-tax net investment (losses) gains			(33,021)	$ (52,954)	31,206	$ 100,833
Realized gain on sale of real estate investment		$ 251,000
Gain on sale of investment	$ 88,000
Real estate impairment			$ 21,000		$ 72,000

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Net Investment (Losses) Gains (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment losses	$ (150,455)	$ (394,832)	$ (62,476)	$ (1,365,064)
Income tax benefit	32,090	79,168	11,626	288,847
Noncontrolling interests	0	0	(1)	(1)
Total change in unrealized gains	(118,365)	(315,664)	(50,851)	(1,076,218)
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment losses	(136,388)	(385,503)	(57,293)	(1,335,413)
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment losses	(10,244)	(4,005)	(3,094)	(20,590)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment losses	(3,217)	(5,031)	(818)	(7,863)
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment losses	$ (606)	$ (293)	$ (1,271)	$ (1,198)

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Fixed Maturity Securities In An Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 5,621,577	$ 8,843,558
Gross Unrealized Losses, Less than 12 Months	120,273	403,241
Fair Value, 12 Months or Greater	11,676,271	6,763,340
Gross Unrealized Losses, 12 Months or Greater	1,047,729	719,593
Fair Value, Total	17,297,848	15,606,898
Gross Unrealized Losses, Total	1,168,002	1,122,834
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	605,944	285,391
Gross Unrealized Losses, Less than 12 Months	17,390	10,219
Fair Value, 12 Months or Greater	592,215	453,520
Gross Unrealized Losses, 12 Months or Greater	64,377	58,939
Fair Value, Total	1,198,159	738,911
Gross Unrealized Losses, Total	81,767	69,158
State and municipal
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	645,642	1,720,443
Gross Unrealized Losses, Less than 12 Months	15,255	89,272
Fair Value, 12 Months or Greater	1,728,892	598,797
Gross Unrealized Losses, 12 Months or Greater	167,938	79,320
Fair Value, Total	2,374,534	2,319,240
Gross Unrealized Losses, Total	183,193	168,592
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	688,848	1,099,549
Gross Unrealized Losses, Less than 12 Months	17,058	75,430
Fair Value, 12 Months or Greater	1,296,384	473,318
Gross Unrealized Losses, 12 Months or Greater	217,712	115,528
Fair Value, Total	1,985,232	1,572,867
Gross Unrealized Losses, Total	234,770	190,958
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	1,025,656	1,569,647
Gross Unrealized Losses, Less than 12 Months	8,774	48,390
Fair Value, 12 Months or Greater	2,584,224	2,176,638
Gross Unrealized Losses, 12 Months or Greater	100,251	103,932
Fair Value, Total	3,609,880	3,746,285
Gross Unrealized Losses, Total	109,025	152,322
Corporate
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	2,091,830	3,690,856
Gross Unrealized Losses, Less than 12 Months	46,758	150,115
Fair Value, 12 Months or Greater	4,695,101	2,349,281
Gross Unrealized Losses, 12 Months or Greater	362,901	256,631
Fair Value, Total	6,786,931	6,040,137
Gross Unrealized Losses, Total	409,659	406,746
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	563,657	477,672
Gross Unrealized Losses, Less than 12 Months	15,038	29,815
Fair Value, 12 Months or Greater	779,455	711,786
Gross Unrealized Losses, 12 Months or Greater	134,550	105,243
Fair Value, Total	1,343,112	1,189,458
Gross Unrealized Losses, Total	$ 149,588	$ 135,058

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Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands	Sep. 30, 2023 USD ($) position	Dec. 31, 2022 USD ($)
Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	95
Aggregate Fair Value	$ 151,750
Gross Unrealized Loss	$ 101,686
Foreign government | Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	44
Aggregate Fair Value	$ 88,668
Gross Unrealized Loss	91,468
Corporate
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	6,786,931	$ 6,040,137
Gross Unrealized Loss	$ 409,659	406,746
Corporate | Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	26
Aggregate Fair Value	$ 35,644
Gross Unrealized Loss	3,523
State and municipal
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	2,374,534	2,319,240
Gross Unrealized Loss	$ 183,193	168,592
State and municipal | Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	5
Aggregate Fair Value	$ 22,866
Gross Unrealized Loss	6,374
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	1,985,232	1,572,867
Gross Unrealized Loss	$ 234,770	190,958
Mortgage-backed | Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	15
Aggregate Fair Value	$ 4,328
Gross Unrealized Loss	214
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	3,609,880	3,746,285
Gross Unrealized Loss	$ 109,025	$ 152,322
Asset-backed | Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	5
Aggregate Fair Value	$ 244
Gross Unrealized Loss	$ 107

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Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Total fixed maturity securities available for sale	$ 18,982,477	$ 17,536,053
Equity securities	1,182,061	1,185,894
Arbitrage trading account	825,000	944,000
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	18,982,477	17,536,053
Equity securities	1,182,061	1,185,894
Arbitrage trading account	825,049	944,230
Total	20,989,587	19,666,177
Liabilities:
Trading account securities sold but not yet purchased	7,538	0
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	1,467,199	892,258
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	2,670,998	2,890,098
Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	2,076,296	1,665,410
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,087,458	3,982,773
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	7,248,814	6,703,992
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,431,712	1,401,522
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	961,433	982,751
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	220,628	203,143
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	958,202	978,991
Arbitrage trading account	614,995	822,192
Total	1,573,197	1,801,183
Liabilities:
Trading account securities sold but not yet purchased	7,538	0
Level 1 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	958,202	978,991
Level 1 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	18,982,477	17,536,053
Equity securities	217,990	193,005
Arbitrage trading account	206,536	118,448
Total	19,407,003	17,847,506
Liabilities:
Trading account securities sold but not yet purchased	0	0
Level 2 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	1,467,199	892,258
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	2,670,998	2,890,098
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	2,076,296	1,665,410
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,087,458	3,982,773
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	7,248,814	6,703,992
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,431,712	1,401,522
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	1,060	1,161
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	216,930	191,844
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	5,869	13,898
Arbitrage trading account	3,518	3,590
Total	9,387	17,488
Liabilities:
Trading account securities sold but not yet purchased	0	0
Level 3 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	2,171	2,599
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	$ 3,698	$ 11,299

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Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Impairments			$ 0
Securities transferred into or out of level 3, net	$ 0	$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	17,488,000	17,488,000	20,590,000
Assets, earnings		(500,000)	(6,871,000)
Assets, other comprehensive income		0	0
Assets, Impairments		(7,601,000)
Assets, purchases		0	5,611,000
Assets, (sales)		0	(1,842,000)
Assets, maturities		0	0
Assets. transfers out			0
Securities transferred into or out of level 3, net		0
Assets, ending balance		9,387,000	17,488,000
Level 3 | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	13,898,000	13,898,000	20,590,000
Assets, earnings		(428,000)	(6,692,000)
Assets, other comprehensive income		0	0
Assets, Impairments		(7,601,000)	0
Assets, purchases		0	925,000
Assets, (sales)		0	(925,000)
Assets, maturities		0	0
Assets. transfers out		0	0
Assets, ending balance		5,869,000	13,898,000
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	2,599,000	2,599,000	9,294,000
Assets, earnings		(428,000)	(6,695,000)
Assets, other comprehensive income		0	0
Assets, Impairments		0	0
Assets, purchases		0	0
Assets, (sales)		0	0
Assets, maturities		0	0
Assets. transfers out		0	0
Assets, ending balance		2,171,000	2,599,000
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	11,299,000	11,299,000	11,296,000
Assets, earnings		0	3,000
Assets, other comprehensive income		0	0
Assets, Impairments		(7,601,000)	0
Assets, purchases		0	925,000
Assets, (sales)		0	(925,000)
Assets, maturities		0	0
Assets. transfers out		0	0
Assets, ending balance		3,698,000	11,299,000
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	$ 3,590,000	3,590,000	0
Assets, earnings		(72,000)	(179,000)
Assets, other comprehensive income		0	0
Assets, Impairments		0
Assets, Impairments			0
Assets, purchases		0	4,686,000
Assets, (sales)		0	(917,000)
Assets, maturities		0	0
Assets. transfers out			0
Securities transferred into or out of level 3, net		0
Assets, ending balance		$ 3,518,000	$ 3,590,000

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Fair Value Measurements (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2023	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Securities transferred into or out of level 3, net	$ 0	$ 0

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Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	$ 14,248,879	$ 12,848,362
Net provision for losses and loss expenses:
Claims occurring during the current year	4,694,554	4,260,179
Decrease in estimates for claims occurring in prior years	27,186	54,632
Loss reserve discount accretion	22,862	24,835
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	4,744,602	4,339,646
Net payments for claims:
Current year	743,416	643,908
Prior years	2,915,979	2,499,319
Total	3,659,395	3,143,227
Foreign currency translation	(48,162)	(193,755)
Net reserves at end of period	15,285,924	13,851,026	$ 14,248,879
Ceded reserves at end of period	2,987,386	2,689,097
Gross reserves at end of period	$ 18,273,310	$ 16,540,123	$ 17,011,223

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Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2023	Sep. 30, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserves discount	$ 35,000,000			$ 35,000,000	$ 26,000,000
Increase (decrease) in estimates for claims				12,000,000	(20,000,000)
Adjustment expense				20,000,000	37,000,000
Liability recognized for best estimate net of reinsurance	354,000,000			354,000,000
Liability recognized for best estimate net of reinsurance, current accident year losses				670,000
Unfavorable reserve development net of premium offsets			$ 24,000,000
Favorable reserve development net of premium offsets	4,000,000	$ 4,000,000
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	299,000,000			299,000,000
Unfavorable reserve development net of premium offsets				26,000,000	33,000,000
Reinsurance & Monoline Excess
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	$ 55,000,000			55,000,000
Unfavorable reserve development net of premium offsets					$ 4,000,000
Favorable reserve development net of premium offsets				$ 6,000,000

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Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Equity securities	$ 1,182,061	$ 1,185,894
Arbitrage trading account	825,000	944,000
Loans receivable	174,300	187,981
Carrying Value
Assets:
Fixed maturity securities	19,035,305	17,587,349
Equity securities	1,182,061	1,185,894
Arbitrage trading account	825,049	944,230
Loans receivable	177,750	193,002
Cash and cash equivalents	1,646,074	1,449,346
Trading account receivables from brokers and clearing organizations	401,982	233,863
Due from broker	0	3,609
Liabilities:
Due to broker	5,118	0
Trading account securities sold but not yet purchased	7,538	0
Senior notes and other debt	1,828,046	1,828,823
Subordinated debentures	1,008,910	1,008,371
Fair Value
Assets:
Fixed maturity securities	19,037,149	17,591,626
Equity securities	1,182,061	1,185,894
Arbitrage trading account	825,049	944,230
Loans receivable	174,300	187,981
Cash and cash equivalents	1,646,074	1,449,346
Trading account receivables from brokers and clearing organizations	401,982	233,863
Due from broker	0	3,609
Liabilities:
Due to broker	5,118	0
Trading account securities sold but not yet purchased	7,538	0
Senior notes and other debt	1,321,014	1,439,188
Subordinated debentures	$ 786,798	$ 805,600

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Premiums and Reinsurance Related Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Written premiums:
Written premiums, direct	$ 3,037,932	$ 2,775,236	$ 8,762,249	$ 8,075,311
Written premiums, assumed	315,273	306,702	977,047	918,864
Written premiums, ceded	(504,746)	(504,664)	(1,504,497)	(1,418,012)
Total net premiums written	2,848,459	2,577,274	8,234,799	7,576,163
Earned premiums:
Earned premiums, direct	2,825,176	2,617,680	8,217,888	7,533,856
Earned premiums, assumed	316,134	318,962	913,795	903,882
Earned premiums, ceded	(499,396)	(494,681)	(1,445,610)	(1,389,533)
Net premiums earned	2,641,914	2,441,961	7,686,073	7,048,205
Ceded losses and loss expenses incurred	320,995	347,439	970,267	905,667
Ceded commissions earned	118,207	121,721	354,148	356,157
Cumulative effect adjustment resulting from changes in accounting principles	$ 9,443	$ 7,999	$ 9,443	$ 7,999	$ 9,365	$ 8,064	$ 7,744	$ 7,713

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Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 30,557	$ 32,770	$ 30,660	$ 25,218
Cumulative effect adjustment resulting from changes in accounting principles	33,602	30,578	33,602	30,578
Change in expected credit losses	832	21	2,942	5,360
Allowance for expected credit losses, end of period	33,602	30,578	33,602	30,578
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	9,365	7,744	8,064	7,713
Cumulative effect adjustment resulting from changes in accounting principles	9,443	7,999	9,443	7,999
Reinsurance Recoverable, Credit Loss Expense (Reversal)	78	255	1,379	286
Allowance for expected credit losses, end of period	$ 9,443	$ 7,999	$ 9,443	$ 7,999

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Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 36,000	$ 34,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)		1,092,130	1,023,871
Fair Value		$ 68,936	$ 67,345
Minimum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period		3 years
Maximum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period		5 years

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Leases (Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
Lease cost	$ 10,122	$ 11,299	$ 30,448	$ 33,649
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	11,403	11,082	33,247	33,128
Right-of-use assets obtained in exchange for new lease liabilities	$ 6,543	$ 1,527	$ 14,489	$ 21,729

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Leases (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
Operating lease, right-of-use asset	$ 155,662	$ 163,940
Operating lease, liability	$ 188,141	$ 199,889
Weighted-average remaining lease term	6 years 10 months 24 days	7 years 1 month 6 days
Weighted-average discount rate	4.55%	4.50%

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Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
2023	$ 12,171
2024	44,531
2025	36,167
2026	28,933
2027	19,144
Thereafter	74,394
Total undiscounted future minimum lease payments	215,340
Less: Discount impact	27,199
Total lease liability	$ 188,141	$ 199,889

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Business Segments (Financial Information of Company Operating Segments) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Earned Premiums (1)	$ 2,641,914	$ 2,441,961	$ 7,686,073	$ 7,048,205
Investment Income	270,944	202,816	739,494	547,902
Other	117,780	79,623	495,989	556,590
Total revenues	3,030,638	2,724,400	8,921,556	8,152,697
Pre-Tax Income (Loss)	419,949	286,265	1,253,205	1,241,260
Net Income (Loss) to Common Stockholders	333,586	228,879	984,020	998,839
Net investment gains	(42,426)	(67,410)	39,239	127,299
Net investment gains, net of tax	(33,021)	(52,954)	31,206	100,833
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	7,893	13,063	30,787	21,837
Other	151,063	138,692	429,180	403,937
Total revenues	158,956	151,755	459,967	425,774
Pre-Tax Income (Loss)	(58,976)	(28,198)	(253,066)	(147,590)
Net Income (Loss) to Common Stockholders	(46,226)	(23,563)	(199,040)	(119,530)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums (1)		2,129,014		6,162,005
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	2,319,435	2,129,014	6,747,704	6,162,005
Investment Income	206,792	134,519	560,182	386,297
Other	9,143	8,341	27,570	25,354
Total revenues	2,535,370	2,271,874	7,335,456	6,573,656
Pre-Tax Income (Loss)	415,279	322,312	1,153,742	1,052,185
Net Income (Loss) to Common Stockholders	329,519	258,521	903,575	850,207
Insurance | Operating Segments | Non-US
Segment Reporting Information [Line Items]
Total revenues	298,000	252,000	852,000	750,000
Reinsurance & Monoline Excess
Segment Reporting Information [Line Items]
Earned Premiums (1)		312,947		886,200
Reinsurance & Monoline Excess | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	322,479	312,947	938,369	886,200
Investment Income	56,259	55,234	148,525	139,768
Other	0	0	0	0
Total revenues	378,738	368,181	1,086,894	1,025,968
Pre-Tax Income (Loss)	106,072	59,561	313,290	209,366
Net Income (Loss) to Common Stockholders	83,314	46,875	248,279	167,329
Reinsurance & Monoline Excess | Operating Segments | Non-US
Segment Reporting Information [Line Items]
Total revenues	124,000	117,000	333,000	307,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	$ 0	$ 0	$ 0	$ 0

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Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 36,111,348	$ 33,815,103
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	28,862,050	27,012,479
Operating Segments | Reinsurance & Monoline Excess
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	5,194,783	5,195,752
Corporate Reconciling Items And Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 2,054,515	$ 1,606,872

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Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue from External Customer [Line Items]
Net premiums earned	$ 2,641,914	$ 2,441,961	$ 7,686,073	$ 7,048,205
Insurance
Revenue from External Customer [Line Items]
Net premiums earned		2,129,014		6,162,005
Insurance | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	2,319,435	2,129,014	6,747,704	6,162,005
Insurance | Other liability
Revenue from External Customer [Line Items]
Net premiums earned	918,054	824,595	2,668,831	2,363,349
Insurance | Short-tail lines
Revenue from External Customer [Line Items]
Net premiums earned	490,598	407,211	1,383,654	1,184,191
Insurance | Commercial automobile
Revenue from External Customer [Line Items]
Net premiums earned	335,572	307,754	965,416	891,729
Insurance | Workers' compensation
Revenue from External Customer [Line Items]
Net premiums earned	300,694	307,323	905,405	892,390
Insurance | Professional liability
Revenue from External Customer [Line Items]
Net premiums earned	274,517	282,131	824,398	830,346
Reinsurance & Monoline Excess
Revenue from External Customer [Line Items]
Net premiums earned		312,947		886,200
Reinsurance & Monoline Excess | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	322,479	312,947	938,369	886,200
Reinsurance & Monoline Excess | Casualty reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	192,071	193,726	574,660	568,507
Reinsurance & Monoline Excess | Monoline excess
Revenue from External Customer [Line Items]
Net premiums earned	60,363	54,675	177,853	161,181
Reinsurance & Monoline Excess | Property reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	$ 70,045	$ 64,546	$ 185,856	$ 156,512