CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY AND COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands	Preferred Stock [Member]	Additional Paid in Capital Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital Common Stock [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss), Net of Tax [Member]	Comprehensive Income (Loss) [Member]	Total
BALANCE at Dec. 31, 2009	$ 0	$ 693,803	$ 117	$ 1,091,047	$ 604,223	$ (105,130)	$ 599		$ 2,284,659
Comprehensive income:
Net income					61,264			61,264	61,264
Net unrealized gain on investment securities available-for-sale, net of taxes and reclassification of net gain included in net income							5,962	5,962	5,962
Noncredit-related impairment loss on securities, net of tax benefits							(4,444)	(4,444)	(4,444)
Foreign currency translation adjustments, net of tax benefits							185	185	185
Total comprehensive income								62,967
Stock compensation costs				3,876					3,876
Tax benefit from stock compensation plans, net				(216)					(216)
Issuance of common stock pursuant to various stock compensation plans and agreements			1	1,800					1,801
Conversion of Series C preferred stock into common stock		(325,299)	37	325,262					0
Cancellation of common stock due to forfeitures of issued restricted stock				2,444		(2,444)			0
Purchase of treasury stock due to the vesting of restricted stock						(444)			(444)
Amortization of Series B preferred stock discount		1,191			(1,191)				0
Preferred stock dividends					(11,094)				(11,094)
Common stock dividends					(2,585)				(2,585)
Repurchase of common stock warrants									0
BALANCE at Jun. 30, 2010	0	369,695	155	1,424,213	650,617	(108,018)	2,302		2,338,964
BALANCE at Dec. 31, 2010	0	83,058	156	1,434,277	720,116	(111,262)	(12,414)		2,113,931
Comprehensive income:
Net income					116,596			116,596	116,596
Net unrealized gain on investment securities available-for-sale, net of taxes and reclassification of net gain included in net income							20,461	20,461	20,461
Noncredit-related impairment loss on securities, net of tax benefits							(2,952)	(2,952)	(2,952)
Foreign currency translation adjustments, net of tax benefits							(665)	(665)	(665)
Total comprehensive income								133,440
Stock compensation costs				5,570					5,570
Tax benefit from stock compensation plans, net				474					474
Issuance of common stock pursuant to various stock compensation plans and agreements				3,341					3,341
Conversion of Series C preferred stock into common stock		(31)		31					0
Cancellation of common stock due to forfeitures of issued restricted stock				2,112		(2,112)			0
Purchase of treasury stock due to the vesting of restricted stock						(572)			(572)
Preferred stock dividends					(3,429)				(3,429)
Common stock dividends					(8,923)				(8,923)
Repurchase of common stock warrants				(14,500)					(14,500)
BALANCE at Jun. 30, 2011	$ 0	$ 83,027	$ 156	$ 1,431,305	$ 824,360	$ (113,946)	$ 4,430		$ 2,229,332