Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 1,052	$ 119,443
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	100,613	(20,229)
Decrease (increase) in funds held by reinsureds, net	(15,006)	(9,734)
Decrease (increase) in reinsurance recoverables	126,897	70,548
Decrease (increase) in income taxes	(12,263)	28,199
Decrease (increase) in prepaid reinsurance premiums	12,266	404
Increase (decrease) in reserve for losses and loss adjustment expenses	287,533	528,078
Increase (decrease) in unearned premiums	(44,708)	68,743
Increase (decrease) in other net payable to reinsurers	7,902	80,245
Increase (decrease) in losses in course of payment	(133,786)	(19,876)
Change in equity adjustments in limited partnerships	(52,915)	(54,558)
Distribution of limited partnership income	39,589	11,015
Change in other assets and liabilities, net	(31,102)	(25,992)
Non-cash compensation expense	9,792	9,004
Amortization of bond premium (accrual of bond discount)	8,217	6,823
Net (gains) losses on investments	226,587	(135,011)
Net cash provided by (used in) operating activities	530,668	657,102
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale	518,038	492,943
Proceeds from fixed maturities sold - available for sale	266,665	76,628
Proceeds from equity securities sold - at fair value	81,975	281,313
Proceeds from distributions and sales of other invested assets	75,895	32,201
Cost of fixed maturities acquired - available for sale	(1,253,493)	(1,140,719)
Cost of equity securities acquired- at fair value	(195,026)	(174,877)
Cost of other invested assets acquired	(74,708)	(51,719)
Net change in short-term investments	122,545	87,694
Net change in unsettled securities transactions	29,268	(99,747)
Net cash provided by (used in) investing activities	(428,842)	(496,283)
CASH FLOWS FROM FINANCING ACTIVITIES:
Tax benefit from share-based compensation, net of expense	(9,679)	(8,896)
Net cash provided by (used in) financing activities	(9,679)	(8,896)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	(3,932)	(11,760)
Net increase (decrease) in cash	88,215	140,163
Cash, beginning of period	699,266	378,518
Cash, end of period	787,481	518,681
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	1,916	2,001
Interest paid	$ 2,210	$ 1,775