CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Member	Additional Paid In Capital Member	Retained Earnings Member	Treasury Stock Member	Accumulated Other Comprehensive Income Member
Total stockholders equity at Dec. 31, 2013	$ 5,935,527	$ 791	$ 1,777,906	$ 3,659,938	$ (508,715)	$ 1,005,607
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	684,047			684,047
Other Comprehensive Income (Loss), Net of Tax	651,522					651,522
Dividends to stockholders	(87,256)			(87,256)
Purchase of treasury stock	(201,525)				(201,525)
Reissuance of treasury stock	(41,137)		(20,373)	(17,082)	(37,846)
Total stockholders equity at Dec. 31, 2014	7,023,452	791	1,798,279	4,239,647	(672,394)	1,657,129
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	502,166			502,166
Other Comprehensive Income (Loss), Net of Tax	(948,845)					(948,845)
Dividends to stockholders	(93,381)			(93,381)
Purchase of treasury stock	(384,519)				(384,519)
Reissuance of treasury stock	(36,508)		(17,863)	(28,129)	(46,774)
Total stockholders equity at Dec. 31, 2015	6,135,381	791	1,816,142	4,620,303	(1,010,139)	708,284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	701,443			701,443
Other Comprehensive Income (Loss), Net of Tax	431,045					431,045
Dividends to stockholders	(100,371)			(100,371)
Purchase of treasury stock	(122,916)				(122,916)
Reissuance of treasury stock	(48,500)		(32,469)	(22,245)	(38,276)
Total stockholders equity at Dec. 31, 2016	$ 7,093,082	$ 791	$ 1,848,611	$ 5,199,130	$ (1,094,779)	$ 1,139,329