Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating Activities
Net income (loss)	$ 427,917	$ 728,604
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses	(141,944)	(262,112)
Net impairment losses recognized in earnings	5,415	16,849
Equity in net income or loss of investment funds accounted for using the equity method and other income or loss	(63,784)	8,157
Amortization of intangible assets	93,942	14,493
Share-based compensation	58,308	46,311
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	602,652	277,277
Unearned premiums, net of ceded unearned premiums	230,581	243,109
Premiums receivable	(167,143)	(198,909)
Deferred acquisition costs	(73,631)	(40,906)
Reinsurance balances payable	37,528	49,198
Other items, net	71,293	155,068
Net Cash Provided By Operating Activities	1,081,134	1,037,139
Investing Activities
Purchases of fixed maturity investments	(28,079,129)	(27,840,555)
Purchases of equity securities	(667,135)	(377,767)
Purchases of other investments	(1,406,528)	(1,008,774)
Proceeds from sales of fixed maturity investments	27,629,474	26,731,924
Proceeds from sales of equity securities	751,873	464,904
Proceeds from sales, redemptions and maturities of other investments	938,581	879,330
Proceeds from redemptions and maturities of fixed maturity investments	747,621	540,823
Net settlements of derivative instruments	(20,952)	23,396
Net (purchases) sales of short-term investments	(964,653)	(604,162)
Change in cash collateral related to securities lending	148,692	(27,935)
Acquisitions, net of cash	(27,709)	(20,911)
Purchases of fixed assets	(16,862)	(11,565)
Other	86,145	(3,816)
Net Cash Provided By (Used For) Investing Activities	(880,582)	(1,255,108)
Financing Activities
Proceeds from issuance of preferred shares, net	222,054	434,899
Redemption of preferred shares	(230,000)	0
Purchases of common shares under share repurchase program	0	(75,256)
Proceeds from common shares issued, net	(7,484)	(3,785)
Proceeds from borrowings	238,915	46,000
Repayments of borrowings	(172,000)	(179,171)
Change in cash collateral related to securities lending	(148,692)	27,935
Dividends paid to redeemable noncontrolling interests	(13,491)	(13,491)
Other	(49,280)	33,113
Preferred dividends paid	(34,936)	(16,453)
Net Cash Provided By (Used For) Financing Activities	(194,914)	253,791
Effects of exchange rate changes on foreign currency cash	13,781	(10,332)
Increase (decrease) in cash	19,419	25,490
Cash beginning of year	842,942	553,326
Cash end of period	862,361	578,816
Income taxes paid	47,907	40,742
Interest paid	$ 64,613	$ 35,234