Allowance for Loan Losses - Recorded Investment Segregated By Amounts Individually Or Collectively In Allowance For Loan Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	$ 971,683	$ 959,109
Balance, end of period: Individually evaluated for impairment	33,239	31,967
Balance, end of period: Collectively evaluated for impairment	938,444	927,142
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	316,081	313,514
Balance, end of period: Individually evaluated for impairment	26,631	26,812
Balance, end of period: Collectively evaluated for impairment	289,450	286,702
Real estate construction one-to-four family
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	30,310	31,201
Balance, end of period: Individually evaluated for impairment	0	0
Balance, end of period: Collectively evaluated for impairment	30,310	31,201
Real estate construction other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	54,947	80,093
Balance, end of period: Individually evaluated for impairment	0	0
Balance, end of period: Collectively evaluated for impairment	54,947	80,093
Real estate term owner occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	132,589	132,042
Balance, end of period: Individually evaluated for impairment	4,584	2,862
Balance, end of period: Collectively evaluated for impairment	128,005	129,180
Real estate term non-owner occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	339,621	319,313
Balance, end of period: Individually evaluated for impairment	861	874
Balance, end of period: Collectively evaluated for impairment	338,760	318,439
Real estate term other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	56,294	40,411
Balance, end of period: Individually evaluated for impairment	541	559
Balance, end of period: Collectively evaluated for impairment	55,753	39,852
Consumer secured by 1st deeds of trust
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	21,896	22,616
Balance, end of period: Individually evaluated for impairment	622	860
Balance, end of period: Collectively evaluated for impairment	21,274	21,756
Consumer other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total financing receivables	19,945	19,919
Balance, end of period: Individually evaluated for impairment	0	0
Balance, end of period: Collectively evaluated for impairment	$ 19,945	$ 19,919