Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	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	267,915										229,017	38,898
Preferred stock cash dividends	(14,674)										(14,674)
Issuance of Series E preferred stock		346,500		350,000						(3,500)
Stock-based compensation plans:
Compensation expense, net	14,122				123			13,999
Exercises of stock options, net	49,494				266			49,228
Stock purchase plan	9,588				43			9,545
Directors' stock plan	441				2			439
Deferred compensation plans, net, including dividend equivalents	(61)				2		(299)	265			(29)
Other	412							412
Common stock cash dividends - $.70 per share	(92,406)										(92,406)
Ending balance at Mar. 31, 2014	11,886,863		1,231,500		65,694		2,616	3,302,402			7,309,912	(25,261)
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	270,116										241,613	28,503
Preferred stock cash dividends	(20,318)										(20,318)
Exercise of stock warrants into common stock						1			(1)
Stock-based compensation plans:
Compensation expense, net	5,572				147			5,425
Exercises of stock options, net	19,479				101			19,378
Stock purchase plan	10,346				45			10,301
Directors' stock plan	425				2			423
Deferred compensation plans, net, including dividend equivalents	(51)				2		(298)	270			(25)
Other	405							405
Common stock cash dividends - $.70 per share	(93,569)										(93,569)
Ending balance at Mar. 31, 2015	$ 12,528,301		$ 1,231,500		$ 66,455		$ 2,310	$ 3,445,707			$ 7,934,820	$ (152,491)