Consolidated Statement of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]
Beginning Balance at Dec. 31, 2011	$ 9,271,209	$ 864,585	$ 62,842	$ 4,072	$ 2,828,986	$ 5,867,165	$ (356,441)
Total comprehensive income	518,435					439,843	78,592
Preferred stock cash dividends	(26,725)					(26,725)
Amortization of preferred stock discount		3,848				(3,848)
Stock-based compensation plans:
Compensation expense, net	18,505		216		18,289
Exercises of stock options, net	25,139		227		24,912
Directors' stock plan	768		4		764
Deferred compensation plans, net, including dividend equivalents	(169)		5	(643)	549	(80)
Other	1,016				1,016
Common stock cash dividends - $1.40 per share	(178,271)					(178,271)
Ending Balance at Jun. 30, 2012	9,629,907	868,433	63,294	3,429	2,874,516	6,098,084	(277,849)
Beginning Balance at Dec. 31, 2012	10,202,593	872,500	64,088	3,473	3,025,520	6,477,276	(240,264)
Total comprehensive income	635,072					622,579	12,493
Preferred stock cash dividends	(26,725)					(26,725)
Amortization of preferred stock discount		4,296				(4,296)
Exercise of 407,542 Series C stock warrants into 186,589 shares of common stock			93		(93)
Stock-based compensation plans:
Compensation expense, net	21,209		153		21,056
Exercises of stock options, net	63,871		366		63,505
Directors' stock plan	797		4		793
Deferred compensation plans, net, including dividend equivalents	(110)		5	(613)	564	(66)
Other	1,321				1,321
Common stock cash dividends - $1.40 per share	(181,698)					(181,698)
Ending Balance at Jun. 30, 2013	$ 10,716,330	$ 876,796	$ 64,709	$ 2,860	$ 3,112,666	$ 6,887,070	$ (227,771)