Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common stocks	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Accumulated Translation Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning and end of period at Dec. 31, 2014		$ 47,024	$ 991,512	$ 5,732,410	$ 306,199	$ (122,649)		$ (2,364,551)	$ 34,189
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			(25,394)
Restricted stock units expensed			23,429
Net income before noncontrolling interests	$ 394,229			393,949					280
Dividends				(43,239)
Change in unrealized investment gains, net of taxes	(78,832)				(78,773)
Unrealized gains on other-than-temporarily impaired securities					47
Change in unrealized currency translation adjustments	(76,713)					(76,713)
Stock exercised/vested								23,667
Stock repurchased								(223,652)
Contributions (distributions)									(992)
Other comprehensive income (loss)	(155,545)					(76,713)	$ (155,545)		(106)
End of period at Sep. 30, 2015			989,547	6,083,120	227,473	(199,362)	28,111	(2,564,536)	33,371
Beginning and end of period at Dec. 31, 2015	4,633,208	$ 47,024	1,005,455	6,178,070	180,695	(247,393)		(2,563,605)	32,962
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			(3,421)
Restricted stock units expensed			25,431
Net income before noncontrolling interests	449,816			449,127					689
Dividends				(107,661)
Change in unrealized investment gains, net of taxes	134,213				133,866
Unrealized gains on other-than-temporarily impaired securities					413
Change in unrealized currency translation adjustments	(77,389)					(77,389)
Stock exercised/vested								5,023
Stock repurchased								(99,870)
Contributions (distributions)									2,474
Other comprehensive income (loss)	56,824					(77,389)	56,824		(66)
End of period at Sep. 30, 2016	$ 4,961,824		$ 1,027,465	$ 6,519,536	$ 314,974	$ (324,782)	$ (9,808)	$ (2,658,452)	$ 36,059