Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated Other Comprehensive Income (Loss)	Unrealized investment gain	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Beginning of period at Dec. 31, 2016		$ 47,024	$ 1,037,446	$ 6,595,987		$ 427,154	$ (371,586)	$ (2,688,817)	$ 33,926
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(295)
Restricted stock units expensed			20,788
Cumulative effect adjustment resulting from changes in accounting principles				0		0
Net income before noncontrolling interests	$ 234,247			232,451					1,796
Dividends				(93,372)
Change in unrealized gains on securities not other-than-temporarily impaired	34,766					33,908
Change in unrealized gains on other-than-temporarily impaired securities						844
Net change in period	42,982						42,982
Stock exercised/vested								1,276
Stock repurchased								0
Stock issued								728
(Distributions) contributions									3,695
Other comprehensive income (loss), net of tax	77,748				$ 77,748		42,982		14
End of period at Jun. 30, 2017			1,057,939	6,735,066	133,302	461,906	(328,604)	(2,686,813)	39,431
Beginning of period at Dec. 31, 2017	5,451,163	$ 47,024	1,048,283	6,956,882		375,421	(306,880)	(2,709,386)	39,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(5,642)
Restricted stock units expensed			17,667
Cumulative effect adjustment resulting from changes in accounting principles				215,939		(214,539)
Net income before noncontrolling interests	348,351			346,472					1,879
Dividends				(96,131)
Change in unrealized gains on securities not other-than-temporarily impaired	(158,214)					(158,199)
Change in unrealized gains on other-than-temporarily impaired securities						11
Net change in period	(91,656)						(91,656)
Stock exercised/vested								6,963
Stock repurchased								(6,799)
Stock issued								688
(Distributions) contributions									(2,162)
Other comprehensive income (loss), net of tax	(249,870)				(249,870)		(91,656)		(26)
End of period at Jun. 30, 2018	$ 5,465,628		$ 1,060,308	$ 7,423,162	$ (395,842)	$ 2,694	$ (398,536)	$ (2,708,534)	$ 39,510