Segment Reporting Selected Segment Income Statement and Balance Sheet Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Income Statement Data Abstract
Net interest income	$ 164,973	$ 157,653
Noninterest income	73,521	82,000
Total revenue	238,494	239,653
Provision for credit losses	5,000	3,300
Noninterest expense	167,658	167,615
Income before income taxes	65,836	68,738
Income tax expense	20,637	21,350
Net income	45,199	47,388
Return on average allocated capital	9.40%	10.10%
Segment Balance Sheet Data
Average earning assets	21,892,503	20,680,919
Average loans	16,164,617	15,448,152
Average deposits	16,990,272	17,146,384
Average allocated capital	1,899,535	1,856,431
Commercial Banking Segment [Member]
Segment Income Statement Data Abstract
Net interest income	73,543	77,180
Noninterest income	24,234	23,169
Total revenue	97,777	100,349
Provision for credit losses	13,032	12,213
Noninterest expense	47,268	46,644
Income before income taxes	37,477	41,492
Income tax expense	13,117	14,522
Net income	24,360	26,970
Return on average allocated capital	12.50%	14.50%
Segment Balance Sheet Data
Average earning assets	8,850,984	8,156,150
Average loans	8,843,070	8,145,829
Average deposits	5,241,027	5,374,633
Average allocated capital	787,257	754,004
Consumer Banking Segment [Member]
Segment Income Statement Data Abstract
Net interest income	71,997	79,191
Noninterest income	43,448	54,195
Total revenue	115,445	133,386
Provision for credit losses	4,948	4,472
Noninterest expense	99,482	102,513
Income before income taxes	11,015	26,401
Income tax expense	3,855	9,240
Net income	7,160	17,161
Return on average allocated capital	5.90%	12.80%
Segment Balance Sheet Data
Average earning assets	7,230,394	7,298,554
Average loans	7,230,394	7,298,554
Average deposits	9,539,887	9,598,352
Average allocated capital	488,425	543,345
Other Segment [Member]
Segment Income Statement Data Abstract
Net interest income	19,433	1,282
Noninterest income	5,839	4,636
Total revenue	25,272	5,918
Provision for credit losses	(12,980)	(13,385)
Noninterest expense	20,908	18,458
Income before income taxes	17,344	845
Income tax expense	3,665	(2,412)
Net income	13,679	3,257
Return on average allocated capital	8.10%	1.40%
Segment Balance Sheet Data
Average earning assets	5,811,125	5,226,215
Average loans	91,153	3,769
Average deposits	2,209,358	2,173,399
Average allocated capital	$ 623,853	$ 559,082