Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Income Statement Data
Net interest income	$ 154,668	$ 153,723
Noninterest income	81,559	72,182
Total revenue	236,227	225,905
Credit provision	0	31,000
Noninterest expense	172,875	164,176
Income (loss) before income taxes	63,352	30,729
Income tax expense (benefit)	20,719	7,876
Net income (loss)	42,633	22,853
Return on average allocated capital	9.20%	3.70%
Segment Balance Sheet Data
Average earning assets	19,371,729	19,297,866
Average loans	14,310,441	12,673,844
Average deposits	15,000,567	14,245,614
Average allocated capital	1,801,649	1,666,614
Commercial Banking [Member]
Segment Income Statement Data
Net interest income	70,086	64,016
Noninterest income	27,816	29,483
Total revenue	97,902	93,499
Credit provision	10,882	9,738
Noninterest expense	58,504	50,372
Income (loss) before income taxes	28,516	33,389
Income tax expense (benefit)	9,981	11,686
Net income (loss)	18,535	21,703
Return on average allocated capital	9.90%	11.70%
Segment Balance Sheet Data
Average earning assets	7,081,463	6,051,968
Average loans	7,078,409	6,049,021
Average deposits	4,352,399	3,386,977
Average allocated capital	746,008	738,870
Consumer Banking [Member]
Segment Income Statement Data
Net interest income	80,239	83,642
Noninterest income	54,457	44,152
Total revenue	134,696	127,794
Credit provision	4,931	4,353
Noninterest expense	106,346	109,206
Income (loss) before income taxes	23,419	14,235
Income tax expense (benefit)	8,197	4,982
Net income (loss)	15,222	9,253
Return on average allocated capital	10.30%	6.90%
Segment Balance Sheet Data
Average earning assets	7,212,426	6,611,525
Average loans	7,212,426	6,611,525
Average deposits	9,432,244	9,445,062
Average allocated capital	591,280	537,805
Risk Management and Shared Services [Member]
Segment Income Statement Data
Net interest income	4,343	6,065
Noninterest income	(714)	(1,453)
Total revenue	3,629	4,612
Credit provision	(15,813)	16,909
Noninterest expense	8,025	4,598
Income (loss) before income taxes	11,417	(16,895)
Income tax expense (benefit)	2,541	(8,792)
Net income (loss)	8,876	(8,103)
Return on average allocated capital	7.60%	(8.30%)
Segment Balance Sheet Data
Average earning assets	5,077,840	6,634,373
Average loans	19,606	13,298
Average deposits	1,215,924	1,413,575
Average allocated capital	$ 464,361	$ 389,939