Loans (Textual) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) loan Segment tenant director employee	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of portfolio segment | Segment	2
Number of classes of loans | loan	6
Minimum number of tenants leased to for non-owner occupied real estate | tenant	1
Loans held-for-sale, at fair value	$ 81,830	$ 10,327
Loans held-for-sale, recorded investment sold	707,800	222,600
Nonaccrual TDRs Reported in Nonaccrual Loans	30,500	35,900
Minimum value of loan requires regional loan committee approval	2,000
Maximum value of loan requires regional loan committee approval	$ 5,000
Minimum due period of loans consider in a nonperforming status	90 days
Interest income recognized on nonaccrual loans while in accruing status	$ 400	900	$ 500
Interest lost on nonaccrual loans	2,900	3,200	3,300
Interest income recognized on TDRs	3,900	3,900	3,600
Real estate properties for which formal foreclosure proceedings are in process	7,300
Impaired Loans	93,066	103,111
Residential Mortgage Loans in Process of Foreclosure		2,900
Commitments to lend additional funds to borrowers whose terms have been modified in TDRs	1,500
Management
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to directors, executive officers and affiliates	23,900	21,700
Loans to directors, executive officers and affiliates, current year additions	33,800	33,300
Loans to directors, executive officers and affiliates, current year reductions	31,600	42,800
Fixed-Rate Real Estate Residential Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-for-sale, at fair value		10,300
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	62,535	67,178
Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	113,446	120,183	116,119
Impaired Financing Receivable, Interest Income, Accrual Method	$ 3,886	3,889	3,558
Land Development Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period for payment of loan	12 months
Commercial Loan | Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 37,388	37,289	35,012
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1,343	1,005	961
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination	80.00%
Residential mortgage | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Upper limit of number of family residential properties | tenant	4
Residential mortgage | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lower limit of number of family residential properties | tenant	1
Residential mortgage | Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 25,477	26,688	26,523
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1,285	1,312	$ 1,252
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum due period of loans consider in a nonperforming status	90 days
Consumer Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Original contractual terms	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	$ 70,785	78,823
Commercial Loan Portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	45,388	$ 46,141
Commercial Loan Portfolio | Commercial Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requires group loan authority approval	$ 2,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities | employee	6
Minimum value of loan requires executive and senior officer approval	$ 2,000
Maximum value of loan requires executive and senior officer approval	3,500
Minimum value of loan requires group loan authority approval	5,000
Maximum value of loan requires group loan authority approval	$ 10,000
Number of members of the board of directors in loan committee | director	8
Commercial Loan Portfolio | Commercial Loan | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other loans requiring director loan committee approval depending on risk rating and credit action required	$ 10,000
Commercial Loan Portfolio | Commercial Loan | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requiring director loan committee approval	10,000
Minimum value of loans requiring board of directors approval	$ 25,000