Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net earnings (loss)	$ 928,219	$ (212,272)	$ 331,799
Net earnings from discontinued operations, net of income taxes	0	0	(10,993)
Adjustments to reconcile net earnings to cash flows used in operating activities:
Realized losses (gains) on sale of investments	(96,328)	27,633	(1,668)
Unrealized losses (gains) on investments	(935,023)	385,251	(188,666)
Depreciation and other amortization	35,583	33,295	36,115
Earnings from equity method investments	(55,910)	(42,147)	(5,904)
Sales and maturities of trading securities	5,829,277	4,802,224	6,111,607
Purchases of trading securities	(4,591,459)	(5,592,311)	(7,544,649)
Net loss on sale of subsidiary	0	0	16,349
Other non-cash items	33,857	11,857	41,087
Changes in:
Reinsurance balances recoverable on paid and unpaid losses	(350,243)	(268,039)	(530,857)
Funds held by reinsured companies	(87,468)	(126,897)	(93,310)
Losses and loss adjustment expenses	1,021,175	960,199	1,363,032
Defendant asbestos and environmental liabilities	(18,142)	(15,844)	(14,857)
Policy benefits for life and annuity contracts	(103,080)	(6,776)	(3,314)
Insurance and reinsurance balances payable	(15,227)	151,918	(157,741)
Unearned premiums	(95,843)	173,725	34,854
Premiums receivable	210,493	(212,423)	(19,026)
Other operating assets and liabilities	53,635	(229,465)	293,035
Net cash flows provided by (used in) operating activities	1,763,516	(160,072)	(343,107)
INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	172,482	(245,151)	(4,185)
Sale of subsidiary, net of cash sold	0	0	126,611
Sales and maturities of available-for-sale securities	344,325	58,219	86,359
Purchase of available-for-sale securities	(2,212,204)	(10,386)	(14,848)
Purchase of other investments	(796,918)	(901,071)	(109,885)
Proceeds from other investments	582,662	436,396	232,827
Purchase of equity method investments	(69,213)	(155,440)	0
Other investing activities	(4,671)	(8,321)	(23,617)
Net cash flows provided by (used in) investing activities	(1,983,537)	(825,754)	293,262
FINANCING ACTIVITIES:
Net proceeds from the issuance of preferred shares	0	495,357	0
Dividends on preferred shares	(35,914)	(12,133)	0
Contribution by redeemable noncontrolling interest	0	49	22
Contribution by redeemable noncontrolling interest	13,127	55,377	0
Dividends paid to noncontrolling interest	(11,556)	(3,852)	(27,458)
Purchase of noncontrolling interest in subsidiaries	(47)	0	0
Receipt of loans	1,070,502	1,132,507	874,100
Repayment of loans	(742,574)	(914,319)	(912,140)
Net cash flows provided by (used in) financing activities	293,538	752,986	(65,476)
EFFECT OF EXCHANGE RATE CHANGES ON FOREIGN CURRENCY CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(324)	2,588	9,512
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	73,193	(230,252)	(105,809)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR	982,584	1,212,836	1,318,645
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR	1,055,777	982,584	1,212,836
Supplemental Cash Flow Information:
Income taxes paid, net of refunds	5,012	17,610	13,192
Interest paid	49,457	25,240	21,487
Reconciliation to Consolidated Balance Sheets:
Cash, cash equivalents and restricted cash	$ 982,584	$ 1,212,836	$ 1,212,836