Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Calculations for basic and diluted earnings per common share
Net income	$ 46,395	$ 41,339	$ 132,345	$ 98,574
Preferred stock dividends and discount accretion	(1,300)	(7,305)	(3,900)	(23,530)
Net income available to common equity	45,095	34,034	128,445	75,044
Common shareholder dividends	(8,594)	(1,734)	(25,893)	(5,200)
Unvested share-based payment awards	(36)	(11)	(116)	(31)
Undistributed earnings	36,465	32,289	102,436	69,813
Undistributed earnings allocated to common shareholders	36,311	32,087	101,975	69,382
Undistributed earnings allocated to unvested share-based payment awards	154	202	461	431
Undistributed earnings	36,465	32,289	102,436	69,813
Basic
Distributed earnings to common shareholders	8,594	1,734	25,893	5,200
Undistributed earnings allocated to common shareholders	36,311	32,087	101,975	69,382
Total common shareholders earnings, basic	44,905	33,821	127,868	74,582
Diluted
Distributed earnings to common shareholders	8,594	1,734	25,893	5,200
Undistributed earnings allocated to common shareholders	36,311	32,087	101,975	69,382
Total common shareholders earnings, diluted	$ 44,905	$ 33,821	$ 127,868	$ 74,582
Weighted average common shares outstanding	171,650,000	173,418,000	172,774,000	173,319,000
Effect of dilutive common stock awards	130,000	0	74,000	2,000
Diluted weighted average common shares outstanding	171,780,000	173,418,000	172,848,000	173,321,000
Basic earnings per common share	$ 0.26	$ 0.20	$ 0.74	$ 0.43
Diluted earnings per common share	$ 0.26	$ 0.20	$ 0.74	$ 0.43
Earnings Per Share (Textuals) [Abstract]
Number of antidilutive stock options excluded from the computation of diluted earnings per share	9,000,000	7,000,000	6,000,000	7,000,000