Acquisitions (Details) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Accumulated other comprehensive income (loss)		$ 55,568			$ 55,568	$ (66,698)
Business acquisition, cost of acquired entity, cash paid			$ 15,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Investments		6,764			6,764
Premium and service fee receivable		144,513			144,513	153,291
Other liabilities assumed		(5,395)			(5,395)
Proceeds from Sales of Business, Affiliate and Productive Assets			$ 253,100		118,200
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net		701			701
Disposal Group, Including Discontinued Operation, Other Assets		37,981			37,981
Other Comprehensive Income (Loss), Net of Tax					122,325	(250,286)	$ (5,808)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest					896,438	732,030	952,196
Income Tax expense		302,593			(292,953)	(227,923)	(302,593)
Net income (loss)					603,485	504,107	649,603
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax					379,258	(192,186)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax					(124,193)	(124,744)
Other Comprehensive Income (Loss), before Tax					255,065	(316,930)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax					(132,740)	66,644
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax					0	0
Other Comprehensive Income (Loss), Tax					(132,740)	66,644
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax					246,518	(125,542)
Net change in period					(124,193)	(124,744)	(62,125)
Worldwide Supplier of After-market (OEM) Parts [Member]
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid				$ 42,300
Business Acquisition, Percentage of Voting Interests Acquired				85.00%
London Acquisition, Inactive insurance Company, and Worldwide Supplier of After-market (OEM) Parts [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Real estate, furniture and equipment		4,202			4,202
Non controlling interest		(3,280)			(3,280)
Allowance For Premiums And Fee Receivable [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Investments		4,399			4,399
Assets, Total [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Total assets acquired		66,328			66,328
Net Assets, Segment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Indefinite-lived Intangible Assets Acquired					$ 57,653
Minimum | Worldwide Supplier of After-market (OEM) Parts [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					2 years
Maximum | Worldwide Supplier of After-market (OEM) Parts [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					15 years
Unrealized investment gains (losses)
Business Acquisition [Line Items]
Accumulated other comprehensive income (loss)		427,154			$ 427,154	180,695	306,199
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Other comprehensive income (loss) before reclassifications					286,734	(119,994)
Amounts reclassified from AOCI					(40,216)	(5,548)
Other Comprehensive Income (Loss), Net of Tax					246,518	(125,542)
Unrealized investment gain related to non-controlling interest					(59)	38
Currency translation adjustments
Business Acquisition [Line Items]
Accumulated other comprehensive income (loss)		(371,586)			(371,586)	(247,393)	(122,649)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Other comprehensive income (loss) before reclassifications					(124,193)	(124,744)
Amounts reclassified from AOCI					0	0
Other Comprehensive Income (Loss), Net of Tax					(124,193)	(124,744)
Unrealized investment gain related to non-controlling interest					0	0
Net change in period					(124,193)	(124,744)	(62,125)
Accumulated other comprehensive income (loss)
Business Acquisition [Line Items]
Accumulated other comprehensive income (loss)		55,568			55,568	(66,698)	$ 183,550
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Other comprehensive income (loss) before reclassifications					162,541	(244,738)
Amounts reclassified from AOCI					(40,216)	(5,548)
Other Comprehensive Income (Loss), Net of Tax					122,325	(250,286)
Unrealized investment gain related to non-controlling interest					(59)	38
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized investment gains (losses)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments	[1]				(61,871)	(8,535)
Income Tax expense	[2]				21,655	2,987
Net income (loss)					(40,216)	(5,548)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Currency translation adjustments
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest					0	0
Income Tax expense					0	0
Net income (loss)					0	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated other comprehensive income (loss)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest					(61,871)	(8,535)
Income Tax expense					21,655	2,987
Net income (loss)					(40,216)	$ (5,548)
Goodwill [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Premium and service fee receivable		12,281			12,281
Other Intangible Assets [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Disposal Group, Including Discontinued Operation, Other Assets		$ 31,800			$ 31,800

[1] Net investment gains in the consolidated statements of income.

[2] Income tax expense in the consolidated statements of income.