Loans - Textual (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment tenant class_of_loan executive	Mar. 31, 2017 USD ($)	Dec. 31, 2017 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	75,465		$ 77,888
Residential mortgage loans in process of foreclosure	3,200		4,200
Commitment to lend additional funds to borrowers whose terms have been modified in TDRs	1,600		2
Loans held-for-sale, at fair value	31,636		52,133
Proceeds from sales of loans	190,435	$ 191,531
Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	26,179		29,106
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	49,286		48,782
Consumer loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	18,335		19,046
Consumer loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	4,265		4,748
Consumer loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	14,070		14,298
Commercial loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	57,130		58,842
Commercial loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	21,914		24,358
Commercial loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	$ 35,216		$ 34,484
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