Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net income (loss)	$ 1,194,372	$ 377,715
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized (gains) losses	(379,049)	(194,776)
Equity in net (income) or loss of investment funds accounted for using the equity method and other income or loss	(181,028)	125,384
Amortization of intangible assets	29,688	33,120
Share-based compensation	57,564	41,912
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	948,505	1,158,446
Unearned premiums, net of ceded unearned premiums	838,650	395,759
Premiums receivable	(781,391)	(463,638)
Deferred acquisition costs	(214,893)	(92,437)
Reinsurance balances payable	331,461	132,161
Other items, net	(231,307)	(192,066)
Net cash provided by (used for) operating activities	1,612,572	1,321,580
Investing Activities
Purchases of fixed maturity investments	(23,554,384)	(25,410,849)
Purchases of equity securities	(620,774)	(1,025,149)
Purchases of other investments	(1,033,134)	(501,692)
Proceeds from sales of fixed maturity investments	23,130,388	24,833,030
Proceeds from sales of equity securities	542,290	580,346
Proceeds from sales, redemptions and maturities of other investments	772,549	472,188
Proceeds from redemptions and maturities of fixed maturity investments	805,836	369,240
Net settlements of derivative instruments	17,286	150,471
Net (purchases) sales of short-term investments	(378,086)	(1,323,363)
Change in cash collateral related to securities lending	(826)	54,596
Purchase of operating affiliate	(546,349)	0
Purchases of fixed assets	(23,585)	(17,687)
Other	(204,889)	8,679
Net cash provided by (used for) investing activities	(1,093,678)	(1,810,190)
Financing Activities
Proceeds from issuance of preferred shares, net	485,821	0
Purchases of common shares under share repurchase program	(485,315)	(75,486)
Proceeds from common shares issued, net	185	(9,661)
Proceeds from borrowings	0	1,004,918
Repayments of borrowings	0	(165,000)
Change in cash collateral related to securities lending	826	(54,596)
Third party investment in non-redeemable noncontrolling interests	15,971	(2,867)
Dividends paid to redeemable noncontrolling interests	(1,907)	(2,540)
Other	27,639	(2,625)
Preferred dividends paid	(20,805)	(20,806)
Net cash provided by (used for) financing activities	22,415	671,337
Effects of exchange rate changes on foreign currency cash and restricted cash	(13,390)	(21,742)
Increase (decrease) in cash and restricted cash	527,919	160,985
Cash and restricted cash, beginning of year	1,290,544	903,698
Cash and restricted cash, end of period	$ 1,818,463	$ 1,064,683