CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ (341,541)	$ 364,460
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized investment losses	14,811	40,295
Net realized and unrealized gains on other investments	(56,759)	(23,117)
Amortization of fixed maturities	32,528	51,660
Interest in loss of equity method investments	8,402	2,434
Other amortization and depreciation	19,279	17,370
Share-based compensation expense, net of cash payments	1,516	28,580
Non-cash foreign exchange losses	24,149	0
Bargain purchase gain	(15,044)	0
Changes in:
Accrued interest receivable	8,730	3,286
Reinsurance recoverable balances	60,522	(163,212)
Deferred acquisition costs	(123,961)	(73,759)
Prepaid reinsurance premiums	(178,464)	(184,648)
Reserve for loss and loss expenses	918,511	216,828
Unearned premiums	540,108	682,686
Insurance and reinsurance balances, net	(465,436)	(623,170)
Other items	(135,266)	(74,383)
Net cash provided by operating activities	312,085	265,310
Cash flows from investing activities:
Fixed maturities	(6,250,608)	(6,624,573)
Equity securities	(108,804)	(295,827)
Mortgage loans	(20,812)	(131,087)
Other investments	(135,526)	(177,500)
Equity method investments	(1,000)	(103,548)
Short-term investments	(20,792)	(81,479)
Proceeds from the sale of:
Fixed maturities	5,354,398	6,067,663
Equity securities	232,755	296,182
Other investments	203,896	170,111
Short-term investments	19,284	67,408
Proceeds from redemption of fixed maturities	1,546,998	977,852
Proceeds from redemption of short-term investments	116,261	8,185
Proceeds from the repayment of mortgage loans	10,702	4,808
Purchase of other assets	(25,842)	(19,055)
Change in restricted cash and cash equivalents	(78,501)	(42,445)
Purchase of subsidiary, net	(73,067)	0
Net cash provided by investing activities	769,342	116,695
Cash flows from financing activities:
Repurchase of common shares	(290,496)	(389,086)
Dividends paid - common shares	(102,868)	(100,670)
Repurchase of preferred shares	(351,074)	(2,843)
Dividends paid - preferred shares	(42,188)	(29,940)
Proceeds from issuance of common shares	0	8
Net cash used in financing activities	(786,626)	(522,531)
Effect of exchange rate changes on foreign currency cash and cash equivalents	16,318	593
Increase (decrease) in cash and cash equivalents	311,119	(139,933)
Cash and cash equivalents - beginning of period	1,039,494	988,133
Cash and cash equivalents - end of period	$ 1,350,613	$ 848,200