Loans - Textual (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) executive	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment tenant class_of_loan executive	Jun. 30, 2018 USD ($)	Dec. 31, 2018 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		$ 3,000
Maximum value of loan that requires regional loan committee approval	7,000		7,000
Total troubled debt restructurings	77,776		77,776		$ 73,655
Residential mortgage loans in process of foreclosure	3,600		3,600		4,500
Commitment to lend additional funds to borrowers whose terms have been modified in TDRs	4,300		4,300		3,200
Loans held-for-sale, at fair value	33,019		33,019		85,030
Proceeds from sales of loans	196,900	$ 202,100	392,730	$ 392,570
Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	29,923		29,923		28,075
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	47,853		47,853		45,580
Consumer loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	15,701		15,701		16,804
Consumer loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	3,397		3,397		3,732
Consumer loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	12,304		12,304		13,072
Commercial loan portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	62,075		62,075		56,851
Commercial loan portfolio | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	26,526		26,526		24,343
Commercial loan portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total troubled debt restructurings	35,549		$ 35,549		$ 32,508
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		$ 1,250
Maximum value of loan requires senior officer approval	$ 3,000		$ 3,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities (in executive) | executive	6		6
Maximum value of loan requires executive and senior officer approval	$ 8,000		$ 8,000
Minimum value of loan requires group loan authority approval	$ 7,000		$ 7,000