Loans And Allowance For Credit Losses (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012 M Y D	Mar. 31, 2011	Dec. 31, 2011
Loans And Allowance For Credit Losses [Line Items]
Unearned income and fees, net of related costs	$ 128,700,000		$ 133,100,000
Owner occupied and commercial real estate loans, unamortized premiums	69,200,000		73,400,000
Loans at carrying value pledged as collateral for current and potential borrowings	20,700,000,000		21,100,000,000
Principle amount of loans held for sale sold	426,000,000	458,000,000
Increase in loans held for sale	408,000,000	434,000,000
Income from loans sold, excluding servicing	6,000,000	3,100,000
Number of days for consumer loans to be charged off	180
Number of days for closed-end loans to be charged off	120
Period of loss migration analysis, maximum months	60
Amounts added to loans held for sale	(20,913,000)	(28,471,000)
Internally assigned loan grades to consumer, commercial lending and commercial real estate loans, minimum	500,000
Threshold for evaluation of impairment	1,000,000
Unused commitments to extend credit on TDR loans	13,000,000		9,000,000
Recorded investment in TDR loans modified with interest rates below market	183,800,000		269,900,000
Credit losses threshold, maximum years	10
Remittance by FDIC recognized in other noninterest income		18,900,000
Acquired foreclosed assets and subsequent real estate foreclosures	28,900,000		24,300,000
Net carrying amount of certain PCI loans	39,400,000		42,600,000
Increase (decrease) on gross provision for loan losses	(400,000)	1,900,000
Charge-offs, net of recoveries and before FDIC indemnification	1,100,000	3,400,000
Total reversal amount to ALLL	2,700,000	4,200,000
Additional noninterest expense due to increased cash flows from acquired loans	10,000,000	13,100,000
Additional interest income due to increased cash flows from acquired loans	$ 13,200,000	$ 19,200,000
Loss sharing reimbursement, maximum	95.00%
Loss sharing reimbursement, minimum	80.00%
Commercial [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, days	90
Consumer [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, days	60