Loans And Allowance For Credit Losses (Narrative) (Details) (USD $)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2012 M	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012 Y M Billing_Cycles Grades Payments D	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011
Loans And Allowance For Credit Losses [Line Items]
Unearned income and fees, net of related costs	$ 133,100,000			$ 133,100,000		$ 133,100,000	$ 133,092,000
Owner occupied and commercial real estate loans, unamortized premiums	64,800,000			64,800,000		64,800,000	73,400,000
Loans at carrying value pledged as collateral for current and potential borrowings	21,000,000,000			21,000,000,000		21,000,000,000	21,100,000,000
Principle amount of loans held for sale sold	449,000,000	392,000,000		875,000,000	850,000,000
Increase in loans held for sale	401,000,000	353,000,000		808,000,000	788,000,000
Income from loans sold, excluding servicing	7,900,000	7,000,000		14,000,000	10,100,000
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
Minimum number of days past due for nonaccrual status				90
Minimum number of monthly payments in arrears when reporting past due				2
Minimum number of billing cycles in arrears when reported as past due				2
Minimum number of days unpaid when reported as past due				30
Maximum loan amount for internally assigned loan grades				500,000
Number of probability of default grades				14
Number of loss given default grades				12
Threshold for nonaccrual loans for evaluation of impairment				1,000,000
Minimum number of months for borrower to meet terms For TDR status				6
Unused commitments to extend credit on TDR loans	14,000,000			14,000,000		14,000,000	9,000,000
Recorded investment in TDR loans modified with interest rates below market	185,300,000			185,300,000		185,300,000	269,900,000
Loans modified as troubled debt restructuring loans						219,500,000
Maximum years of FDIC coverage				10
Remittance by FDIC recognized in other noninterest income			18,900,000
Acquired foreclosed assets and subsequent real estate foreclosures	19,700,000			19,700,000		19,700,000	24,300,000
Net carrying amount of certain PCI loans	39,700,000			39,700,000		39,700,000	42,600,000
Increase (decrease) on gross provision for loan losses	(6,900,000)	2,900,000		(7,300,000)	300,000
Charge-offs (recoveries), net before FDIC indemnification	(7,800,000)	2,500,000		(6,700,000)	10,500,000
Total reversal amount to ALLL	7,900,000	4,800,000		10,600,000	9,000,000
Additional interest income due to increased cash flows from acquired loans	14,800,000	15,000,000		27,900,000	28,100,000
Additional noninterest expense due to increased cash flows from acquired loans	$ 11,200,000	$ 21,500,000		$ 21,200,000	$ 40,700,000
Loss sharing reimbursement, minimum	80.00%			80.00%		80.00%
Loss sharing reimbursement, maximum	95.00%			95.00%		95.00%
Commercial [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, number of days				90
Consumer [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, number of days				60