Loans And Allowance For Credit Losses (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014 Payments Billing_Cycles D M	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Loans And Allowance For Credit Losses [Line Items]
Threshold for Internal risk grades assigned to commercial and commercial real estate loans	$ 750,000		$ 750,000
Unused Commitments to Extend Credit	3,800,000		3,800,000		5,600,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Provision for Loan Losses	(2,700,000)	(9,600,000)
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	327,000	1,316,000	142,400,000	181,500,000
Unearned income and fees, net of related costs	144,500,000		144,500,000		141,700,000
Owner occupied and commercial real estate loans, unamortized premiums	44,100,000		44,100,000		47,200,000
Land Development Loans	589,100,000		589,100,000		561,300,000
Loans at carrying value pledged as collateral for current and potential borrowings	23,500,000,000		23,500,000,000		23,000,000,000
Payments for Origination and Purchases of Loans Held-for-sale	295,500,000	358,900,000
Loans and Leases Receivable, Gain (Loss) on Sales, Net	3,500,000	8,500,000
Principle amount of loans held for sale sold	337,600,000	447,600,000
Number of days for consumer loans to be charged off	180
Number of days for closed-end loans to be charged off	120
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
Threshold for nonaccrual loans for evaluation of impairment	1,000,000
Minimum number of months for borrower to meet terms For TDR status	6
Recorded investment in TDR loans modified with interest rates below market	186,200,000		186,200,000		172,600,000
Charge-offs (recoveries), net before FDIC indemnification	(1,200,000)	(900,000)
Total reversal amount to ALLL	2,900,000	9,700,000
Additional interest income due to increased cash flows from acquired loans	18,500,000	20,300,000
Additional noninterest expense due to increased cash flows from acquired loans	16,000,000	19,000,000
Loss sharing reimbursement, minimum	80.00%		80.00%
Loss sharing reimbursement, maximum	95.00%		95.00%
FDIC Indemnification Asset	$ 13,200,000		$ 13,200,000		$ 26,400,000
Commercial [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, number of days	90
Consumer Portfolio Segment [Member]
Loans And Allowance For Credit Losses [Line Items]
Subsequent payment default period, number of days	60