Loans - Textual (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) class_of_loan segment tenant executive	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of portfolio segment (in segment) | segment	2
Number of classes of loans (in class of loan) | class_of_loan	6
Number of minimum tenants under lease of non-owner occupied commercial real estate (in tenant) | tenant	1
Minimum value of loan that requires regional loan committee approval	$ 3,000
Maximum value of loan that requires regional loan committee approval	7,000
Total troubled debt restructurings	79,793	$ 93,066
Residential mortgage loans in process of foreclosure	3,400	7,300
Commitment to lend additional funds to borrowers whose terms have been modified in TDRs	1,800
Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	24,004	30,531
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	55,789	62,535
Consumer loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	19,565	22,281
Consumer loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	4,662	5,134
Consumer loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	14,903	17,147
Commercial loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	60,228	70,785
Commercial loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	19,342	25,397
Commercial loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	$ 40,886	$ 45,388
Land development loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period for payment of loan	12 months
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%
Commercial | Commercial loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requires group loan authority approval	$ 1,250
Maximum value of loan requires senior officer approval	$ 3,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities (in executive) | executive	6
Maximum value of loan requires executive and senior officer approval	$ 8,000
Minimum value of loan requires group loan authority approval	$ 7,000