Loans (Textual) (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) loan Segment tenant employee	Dec. 31, 2017 USD ($)	Dec. 31, 2016 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	$ 85,030,000	$ 52,133,000
Minimum value of loan requires regional loan committee approval	3,000,000
Maximum value of loan requires regional loan committee approval	$ 7,000,000
Minimum due period of loans consider in a nonperforming status	90 days
Nonaccrual TDRs reported in nonaccrual loans	$ 28,100,000	29,100,000
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	2,100,000	1,300,000	$ 400,000
Interest lost on nonaccrual loans	4,800,000	3,100,000	2,900,000
Interest income recognized on TDRs	2,700,000	2,600,000	3,900,000
Real estate properties for which formal foreclosure proceedings are in process	4,500,000
Residential mortgage loans in process of foreclosure		4,200,000
Impaired loans	73,655,000	77,888,000
Commitments to lend additional funds to borrowers whose terms have been modified in TDRs	3,200,000	2,000,000
Proceeds from sales of loans	741,902,000	838,549,000	$ 723,521,000
Management
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to directors, executive officers and affiliates	3,600,000	3,800,000
Loans to directors, executive officers and affiliates, current year additions	3,800,000	44,100,000
Loans to directors, executive officers and affiliates, current year reductions	4,000,000	64,200,000
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	45,580,000	48,782,000
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	56,851,000	58,842,000
Commercial Loan Portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	$ 32,508,000	$ 34,484,000
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%
Residential mortgage | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lower limit of number of family residential properties | tenant	1
Residential mortgage | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Upper limit of number of family residential properties | tenant	4
Commercial | Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requires group loan authority approval	$ 3,000,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities | employee	6
Maximum value of loan requires executive and senior officer approval	$ 8,000,000
Minimum value of loan requires group loan authority approval	$ 7,000,000
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
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	$ 0