Consolidated Statements Of Shareholder's Equity - USD ($) $ in Thousands	Total		Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2012	$ 4,361,786		$ 0	$ 158,718	$ 439,782	$ 925,275	$ 3,350,432	$ (512,421)
Increase (Decrease) in Stockholders' Equity
Other Comprehensive income (loss)	(185,822)					(714,294)	528,472
Common dividends declared ($.45 in 2013, $.51 in 2014 and $.54 in 2015 a share)	(61,991)						(61,991)
Acquisition of treasury stock	(482,264)							(482,264)
Stock-based compensation	25,642				23,464		563	1,615
Exercise of stock options	118,991				21,315		(25,195)	122,871
Retirement of treasury stock	0			(7,500)	(22,503)		(296,748)	326,751
Ending balance at Dec. 31, 2013	3,776,342		0	151,218	462,058	210,981	3,495,533	(543,448)
Increase (Decrease) in Stockholders' Equity
Other Comprehensive income (loss)	1,329,410					786,471	542,939
Common dividends declared ($.45 in 2013, $.51 in 2014 and $.54 in 2015 a share)	(65,998)						(65,998)
Acquisition of treasury stock	(449,308)							(449,308)
Stock-based compensation	32,203				31,315		362	526
Exercise of stock options	74,817				18,524		(22,641)	78,934
Retirement of treasury stock	0			(17,000)	(54,284)		(573,349)	644,633
Ending balance at Dec. 31, 2014	4,697,466	[1]	0	134,218	457,613	997,452	3,376,846	(268,663)
Increase (Decrease) in Stockholders' Equity
Other Comprehensive income (loss)	(238,405)					(765,505)	527,100
Common dividends declared ($.45 in 2013, $.51 in 2014 and $.54 in 2015 a share)	(67,182)						(67,182)
Acquisition of treasury stock	(418,526)							(418,526)
Stock-based compensation	28,664				21,813		(2,132)	8,983
Exercise of stock options	53,535				17,577		(36,322)	72,280
Retirement of treasury stock	0			(4,000)	(14,719)		(183,941)	202,660
Ending balance at Dec. 31, 2015	$ 4,055,552		$ 0	$ 130,218	$ 482,284	$ 231,947	$ 3,614,369	$ (403,266)

[1] Certain balances were adjusted to give effect to discontinued operations as described in Note 1—Significant Accounting Policies.