Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net income (loss)	$ 866,397	$ 1,380,532
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized (gains) losses	(477,683)	(326,532)
Equity in net income or loss of investment funds accounted for using the equity method and other income or loss	30,306	(38,912)
Amortization of intangible assets	49,835	60,214
Share-based compensation	56,433	54,432
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	1,668,069	377,074
Unearned premiums, net of ceded unearned premiums	498,811	312,998
Premiums receivable	(461,766)	(328,765)
Deferred acquisition costs	(107,238)	(38,606)
Reinsurance balances payable	205,620	214,902
Other items, net	2,666	(124,198)
Net cash provided by (used for) operating activities	2,331,450	1,543,139
Investing Activities
Purchases of fixed maturity investments	(34,050,883)	(24,010,623)
Purchases of equity securities	(1,355,848)	(524,051)
Purchases of other investments	(841,886)	(1,014,925)
Proceeds from sales of fixed maturity investments	32,544,867	22,707,854
Proceeds from sales of equity securities	731,793	371,130
Proceeds from sales, redemptions and maturities of other investments	791,807	827,517
Proceeds from redemptions and maturities of fixed maturity investments	645,292	394,719
Net settlements of derivative instruments	163,290	92,423
Net (purchases) sales of short-term investments	(1,159,351)	129,078
Change in cash collateral related to securities lending	81,210	6,990
Purchases of fixed assets	(26,717)	(27,635)
Other	(131,992)	(202,953)
Net cash provided by (used for) investing activities	(2,608,418)	(1,250,476)
Financing Activities
Purchases of common shares under share repurchase program	(75,486)	(2,871)
Proceeds from common shares issued, net	(9,656)	518
Proceeds from borrowings	1,018,793	200,083
Repayments of borrowings	(304,000)	(27,538)
Change in cash collateral related to securities lending	(81,210)	(6,990)
Third party investment in non-redeemable noncontrolling interests	(2,867)	0
Change in third party investment in redeemable noncontrolling interests	0	(161,874)
Dividends paid to redeemable noncontrolling interests	(3,541)	(11,408)
Other	55,266	(5,207)
Preferred dividends paid	(31,209)	(31,209)
Net cash provided by (used for) financing activities	566,090	(46,496)
Effects of exchange rate changes on foreign currency cash and restricted cash	(5,847)	(8,335)
Increase (decrease) in cash and restricted cash	283,275	237,832
Cash and restricted cash, beginning of year	903,698	724,643
Cash and restricted cash, end of period	$ 1,186,973	$ 962,475