Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities
Net income (loss)	$ (88,674)	$ 495,498
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized (gains) losses	362,964	(144,091)
Equity in net income or loss of investment funds accounted for using the equity method and other income or loss	29,034	(29,752)
Amortization of intangible assets	16,631	20,417
Share-based compensation	28,549	25,891
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	506,057	(6,005)
Unearned premiums, net of ceded unearned premiums	392,802	156,393
Premiums receivable	(418,457)	(285,137)
Deferred acquisition costs	(75,135)	(23,168)
Reinsurance balances payable	79,807	62,605
Other items, net	(223,124)	(37,253)
Net cash provided by (used for) operating activities	610,454	235,398
Investing Activities
Purchases of fixed maturity investments	(11,965,995)	(7,444,470)
Purchases of equity securities	(760,683)	(203,810)
Purchases of other investments	(228,471)	(324,593)
Proceeds from sales of fixed maturity investments	11,723,123	7,076,590
Proceeds from sales of equity securities	266,301	95,017
Proceeds from sales, redemptions and maturities of other investments	216,131	216,483
Proceeds from redemptions and maturities of fixed maturity investments	198,356	100,424
Net settlements of derivative instruments	195,488	29,737
Net (purchases) sales of short-term investments	(11,777)	292,601
Change in cash collateral related to securities lending	55,001	(29,618)
Purchases of fixed assets	(8,470)	(9,423)
Other	42,500	(93,731)
Net cash provided by (used for) investing activities	(278,496)	(294,793)
Financing Activities
Purchases of common shares under share repurchase program	(75,486)	(2,871)
Proceeds from common shares issued, net	(4,527)	(1,901)
Proceeds from borrowings	16,300	59,000
Repayments of borrowings	0	(26,038)
Change in cash collateral related to securities lending	(55,001)	29,618
Third party investment in non-redeemable noncontrolling interests	(2,867)	0
Dividends paid to redeemable noncontrolling interests	(1,181)	(4,497)
Other	(1,331)	(1,389)
Preferred dividends paid	(10,403)	(10,403)
Net cash provided by (used for) financing activities	(134,496)	41,519
Effects of exchange rate changes on foreign currency cash and restricted cash	(30,723)	3,449
Increase (decrease) in cash and restricted cash	166,739	(14,427)
Cash and restricted cash, beginning of year	903,698	724,643
Cash and restricted cash, end of period	$ 1,070,437	$ 710,216