Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series E Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member] Series E Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series A Warrants [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series A Warrants [Member]	Additional Paid-in Capital [Member] Series E Preferred Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]
Beginning balance at Dec. 31, 2013	$ 11,305,532		$ 881,500		$ 65,258		$ 2,915	$ 3,232,014			$ 7,188,004	$ (64,159)
Total comprehensive income	865,323										788,697	76,626
Preferred stock cash dividends	(55,560)										(55,560)
Exercise of stock warrants into common stock						$ 78			$ (78)
Issuance of Series E preferred stock		$ 346,500		$ 350,000						$ (3,500)
Stock-based compensation plans:
Compensation expense, net	34,245				128			34,117
Exercises of stock options, net	103,230				535			102,695
Stock purchase plan	9,588				43			9,545
Directors' stock plan	1,271				5			1,266
Deferred compensation plans, net, including dividend equivalents	(74)				3		(325)	335			(87)
Other	1,320							1,320
Common stock cash dividends - $2.10 per share	(278,059)										(278,059)
Ending balance at Sep. 30, 2014	12,333,316		1,231,500		66,050		2,590	3,377,714			7,642,995	12,467
Beginning balance at Dec. 31, 2014	12,335,896		1,231,500		66,157		2,608	3,409,506			7,807,119	(180,994)
Total comprehensive income	826,223										808,702	17,521
Preferred stock cash dividends	(60,953)										(60,953)
Exercise of stock warrants into common stock						$ 1			$ (1)
Stock-based compensation plans:
Compensation expense, net	31,559				143			31,416
Exercises of stock options, net	57,418				285			57,133
Stock purchase plan	10,346				45			10,301
Directors' stock plan	1,350				4			1,346
Deferred compensation plans, net, including dividend equivalents	(51)				2		(267)	290			(76)
Other	1,191							1,191
Common stock cash dividends - $2.10 per share	(281,045)										(281,045)
Ending balance at Sep. 30, 2015	$ 12,921,934		$ 1,231,500		$ 66,637		$ 2,341	$ 3,511,182			$ 8,273,747	$ (163,473)