CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	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, 2011	$ 5,818,698	$ 791	$ 1,727,774	$ 2,818,429	$ (346,449)	$ 1,618,153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	631,893			631,893
Other Comprehensive Income (Loss), Net of Tax	490,749					490,749
Dividends to stockholders	(61,945)			(61,945)
Purchase of treasury stock	(6,924)				(6,924)
Reissuance of treasury stock	37,716		27,647	(31,122)	41,191
Total stockholders equity at Dec. 31, 2012	6,910,187	791	1,755,421	3,357,255	(312,182)	2,108,902
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	418,837			418,837
Other Comprehensive Income (Loss), Net of Tax	(1,103,295)					(1,103,295)
Dividends to stockholders	(77,642)			(77,642)
Purchase of treasury stock	(269,204)				(269,204)
Reissuance of treasury stock	56,644		22,485	(38,512)	72,671
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	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