Loans And Allowance For Credit Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) mo Billing_Cycles d Payments	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loans And Allowance For Credit Losses [Line Items]
Loans Receivable Commercial Construction and Land Development	$ 289,800,000	$ 288,000,000
Impaired Financing Receivable, Recorded Investment	659,759,000	566,599,000
Loans Pledged as Collateral	24,000,000,000	19,400,000,000
Unearned income and fees, net of related costs	77,000,000	81,000,000
Owner occupied and commercial real estate loans, unamortized premiums	19,900,000	26,200,000
Principle amount of loans held for sale sold	1,400,000,000	1,400,000,000	$ 1,200,000,000
Loans Sold and Serviced	2,000,000,000	2,000,000,000
Additions to Loans Held For Sale	1,400,000,000	1,400,000,000	1,200,000,000
Income from loans sold, excluding servicing	$ 18,100,000	17,800,000	15,100,000
Number of days for consumer loans to be charged off | d	180
Minimum number of days past due for nonaccrual status | d	90
Minimum number of monthly payments in arrears when reporting past due | Payments	2
Minimum number of billing cycles in arrears when reported as past due | Billing_Cycles	2
Minimum number of days unpaid when reported as past due | d	30
Maximum loan amount for internally assigned loan grades	$ 750,000
Threshold for nonaccrual loans for evaluation of impairment	$ 1,000,000
Minimum number of months for borrower to meet terms For TDR status | mo	6
Unused commitments to extend credit on TDR loans	$ 14,300,000	7,500,000
Recorded investment in TDR loans modified with interest rates below market	127,900,000	188,000,000
Loans modified as troubled debt restructuring loans	72,500,000	134,000,000
Increase (decrease) on gross provision for loan losses	900,000	300,000	(1,700,000)
Total reversal amount to ALLL	2,200,000	3,700,000	4,600,000
Additional interest income due to increased cash flows from acquired loans	18,600,000	31,600,000	$ 46,700,000
Other Real Estate, Foreclosed Assets, Residential Real Estate	1,900,000	500,000
Other Real Estate, In Process of Forecloseing Assets	9,600,000	12,500,000
Owner Occupied [Member]
Loans And Allowance For Credit Losses [Line Items]
Impaired Financing Receivable, Recorded Investment	100,696,000	126,267,000
Commercial Portfolio Segment [Member]
Loans And Allowance For Credit Losses [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 494,485,000	335,137,000
Subsequent payment default period, number of days | d	90
Consumer [Member]
Loans And Allowance For Credit Losses [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 1,140,000	$ 2,606,000
Subsequent payment default period, number of days | d	60