Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net Income (loss)	$ (130,353)	$ 400,758	$ 460,443
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income tax expense (benefit)	2,729	(324,090)	63,358
Depreciation and amortization	227,846	203,871	194,147
Net realized investment losses (gains)	437,596	5,303	(65,147)
Loss on early extinguishment of debt	0	0	44,100
Net foreign exchange losses (gains)	(106,598)	(3,140)	1,253
Impairment of Goodwill and Intangible Assets	199,198	0	18,723
Increase in receivables	(27,961)	(38,259)	(163,123)
Increase in deferred policy acquisition costs	(15,585)	(67,923)	(41,619)
Increase (decrease) in unpaid losses and loss adjustment expenses, net	298,796	619,305	(9,429)
Decrease in life and annuity benefits	(50,541)	(55,647)	(54,580)
Increase in unearned premiums, net	62,879	197,706	134,593
Increase (decrease) in payables to insurance and reinsurance companies	(4,313)	(40,761)	11,582
Increase (decrease) in income taxes payable	53,730	(35,968)	(16,484)
Increase (decrease) in accrued expenses	(23,756)	(71,669)	67,994
Increase (decrease) in other liabilities	(5,637)	45,051	(90,571)
Other	(25,173)	23,992	(20,617)
Net Cash Provided By Operating Activities	892,857	858,529	534,623
INVESTING ACTIVITIES
Proceeds from sales of fixed maturities and equity securities	419,199	577,650	365,822
Proceeds from maturities, calls and prepayments of fixed maturities	551,808	1,129,895	963,165
Cost of fixed maturities and equity securities purchased	(1,545,913)	(1,176,281)	(2,205,939)
Net change in short-term investments	1,101,636	234,743	(689,194)
Additions to property and equipment	(106,593)	(74,652)	(63,674)
Acquisitions, net of cash acquired	(1,175,211)	(1,431,712)	(7,527)
Other	(42,165)	(4,100)	(1,134)
Net Cash Provided (Used) By Investing Activities	(797,239)	(744,457)	(1,638,481)
FINANCING ACTIVITIES
Additions to senior long-term debt and other debt	206,949	664,657	559,300
Repayment of senior long-term debt and other debt	(289,199)	(259,972)	(278,363)
Premiums and fees related to early extinguishment of debt	0	0	(43,691)
Repurchases of common stock	(54,007)	(110,838)	(51,142)
Payment for Contingent Consideration	15,914	5,018	14,219
Purchase of noncontrolling interests	(13,523)	(18,334)	(3,167)
Distributions to noncontrolling interests	(9,164)	(7,899)	(5,949)
Other	(4,127)	(6,281)	(10,750)
Net Cash Provided (Used) By Financing Activities	(178,985)	256,315	152,019
Effect of foreign currency rate changes on cash, cash equivalents, restricted cash and restricted cash equivalents	(21,047)	45,295	(33,138)
Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents	(104,414)	415,682	(984,977)
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year	2,500,846	2,085,164	3,070,141
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND RESTRICTED CASH EQUIVALENTS AT END OF YEAR	$ 2,396,432	$ 2,500,846	$ 2,085,164