Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income (loss)	$ 137	$ 419	$ 368
Adjustments to reconcile net income to net cash flows provided by operating activities:
Non-cash interest and operating expenses	65	69	54
Provision (benefit) for deferred income taxes	(3)	(38)	58
Net realized investment losses (gains)	56	(15)	(18)
Equity in (earnings) losses of investees	39	(94)	(27)
Fair value losses (gains) on trading securities	34	0	0
Loss on extinguishment of debt	0	175	0
Change in premiums receivable, net of premiums and commissions payable	74	0	(102)
Change in unearned premium reserve, net	(93)	(17)	19
Change in loss and loss adjustment expense reserve, net	(1,207)	(99)	(174)
Change in current income taxes	(106)	64	9
Change in credit derivative assets and liabilities, net	8	54	(85)
Other	(56)	20	(1)
Cash flows from consolidated investment vehicles:
Purchases of securities	(3,201)	(4,957)	(2,053)
Sales of securities	1,513	2,161	1,156
Maturities and paydowns of securities	156	430	71
Proceeds from (purchases of) money market funds	6	(6)	(108)
Purchases to cover securities sold short	(223)	(621)	(460)
Proceeds from securities sold short	188	618	509
Other changes in consolidated investment vehicles	134	(100)	(69)
Net cash flows provided by (used in) operating activities	(2,479)	(1,937)	(853)
Fixed-maturity securities, available for sale:
Purchases	(371)	(1,236)	(1,380)
Sales	717	428	779
Maturities and paydowns	682	1,148	878
Short-term investments with original maturities of over three months:
Purchases	(63)	0	(85)
Sales	0	0	5
Maturities and paydowns	36	36	73
Net sales (purchases) of short-term investments with original maturities of less than three months	439	(410)	430
Fixed-maturity securities, trading:
Sales	121	0	0
Maturities and paydowns	87	0	0
Purchases of other invested assets	(25)	(79)	(19)
Sales and return of capital of other invested assets	36	80	23
Paydowns on financial guaranty variable interest entities’ assets	84	62	83
Other	(3)	(6)	1
Net cash flows provided by (used in) investing activities	1,740	23	788
Cash flows from financing activities:
Dividends paid	(64)	(66)	(69)
Repurchases of common shares	(500)	(496)	(446)
Net paydowns of financial guaranty variable interest entities’ liabilities	(99)	(53)	(77)
Net proceeds from issuance of debt	0	889	0
Redemptions and purchases of debt, including make-whole payment	(2)	(620)	(22)
Other	(6)	26	(10)
Cash flows from consolidated investment vehicles:
Proceeds from issuance of collateralized loan obligations	1,372	3,276	738
Repayment of collateralized loan obligations	(373)	(824)	0
Proceeds from issuance of warehouse financing debt	991	1,338	234
Repayment of warehouse financing debt	(796)	(1,537)	(210)
Contributions from noncontrolling interests to consolidated investment vehicles	74	39	88
Distributions to noncontrolling interests from consolidated investment vehicles	(26)	(12)	(43)
Proceeds from (Repayments of) Lines of Credit	41	0	0
Net cash flows provided by (used in) financing activities	612	1,960	183
Effect of foreign exchange rate changes	(8)	(2)	(3)
Increase (decrease) in cash and cash equivalents and restricted cash	(135)	44	115
Cash and cash equivalents and restricted cash at beginning of period	342	298	183
Cash and cash equivalents and restricted cash at end of period	207	342	298
Supplemental cash flow information
Income taxes paid (received)	105	24	(25)
Interest paid on long-term debt	77	80	81
Supplemental disclosure of non-cash activities:
Fixed-maturity securities, available-for-sale, received as salvage	986	0	0
Fixed-maturity securities, available-for-sale, ceded to a reinsurer	27	0	0
Fixed-maturity securities, trading, received as salvage	549	0	0
Fixed-maturity securities, trading, ceded to a reinsurer	6	0	0
Debt securities of financial guaranty variable interest entities received as salvage	234	0	0
Contributions from noncontrolling interests	36	1	0
Distributions to noncontrolling interests	56	1	0
Reconciliation of cash and cash equivalents and restricted cash to the consolidated balance sheets:
Cash	107	120	162
Restricted cash (included in other assets)	1	2	2
Cash of Financial Guaranty Variable Interest Entities	2	0	0
Cash and cash equivalents of consolidated investment vehicles (see Note 8)	97	220	134
Cash and cash equivalents and restricted cash at the end of period	$ 207	$ 342	$ 298