Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 46,052	$ 532,530
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	(147,210)	(93,371)
Decrease (increase) in funds held by reinsureds, net	(13,336)	(13,929)
Decrease (increase) in reinsurance receivables	233,199	82,701
Decrease (increase) in income taxes	(41,843)	214,671
Decrease (increase) in prepaid reinsurance premiums	15,928	(110,643)
Increase (decrease) in reserve for losses and loss adjustment expenses	205,192	(21,387)
Increase (decrease) in unearned premiums	90,640	176,412
Increase (decrease) in other net payable to reinsurers	89,520	3,307
Increase (decrease) in losses in course of payment	118,964	(22,634)
Change in equity adjustments in limited partnerships	50,809	(23,662)
Distribution of limited partnership income	30,916	24,969
Change in other assets and liabilities, net	(75,931)	(65,421)
Non-cash compensation expense	15,462	13,913
Amortization of bond premium (accrual of bond discount)	4,436	826
Net realized capital (gains) losses	222,493	(277,619)
Net cash provided by (used in) operating activities	845,291	420,663
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale, at market value	494,544	437,371
Proceeds from fixed maturities sold - available for sale, at market value	337,723	2,004,602
Proceeds from fixed maturities sold - available for sale, at fair value		2,706
Proceeds from equity securities sold - at fair value	213,003	148,973
Distributions from other invested assets	119,727	76,149
Cost of fixed maturities acquired - available for sale, at market value	(1,226,251)	(2,251,818)
Cost of equity securities acquired- at fair value	(222,818)	(228,872)
Cost of other invested assets acquired	(215,569)	(138,096)
Net change in short-term investments	(308,979)	(192,889)
Net change in unsettled securities transactions	37,744	13,100
Net cash provided by (used in) investing activities	(770,876)	(128,774)
CASH FLOWS FROM FINANCING ACTIVITIES:
Tax benefit from share-based compensation, net of expense	(15,258)	(13,739)
Cost of debt repurchase	(10,648)
Proceeds from issuance (cost of repayment) of note payable-affiliated		(300,000)
Net cash provided by (used in) financing activities	(25,906)	(313,739)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	(14,015)	(5,483)
Net increase (decrease) in cash	34,495	(27,333)
Cash, beginning of period	411,122	404,522
Cash, end of period	445,617	377,189
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	4,763	(87,045)
Interest paid	$ 14,782	$ 19,433