Allowance for Loan Losses - Allowance For Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	$ 20,061	$ 18,385	$ 19,697	$ 18,153
Charge-Offs	(1,203)	(22)	(1,689)	(891)
Recoveries	106	464	256	662
Provision (benefit)	2,500	652	3,200	1,555
Balance, end of period	20,061	18,385	19,697	18,153	$ 21,464	$ 19,479
Balance, end of period: Individually evaluated for impairment					1,514	535
Balance, end of period: collectively evaluated for impairment					19,950	18,944
Commercial
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	5,822	5,867	5,535	5,906
Charge-Offs	(1,118)	0	(1,582)	(868)
Recoveries	102	450	246	643
Provision (benefit)	2,210	(278)	2,817	358
Balance, end of period	5,822	5,867	5,535	5,906	7,016	6,039
Balance, end of period: Individually evaluated for impairment					1,514	0
Balance, end of period: collectively evaluated for impairment					5,502	6,039
Real estate construction one-to-four family
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	521	892	550	854
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit)	79	306	50	344
Balance, end of period	521	892	550	854	600	1,198
Balance, end of period: Individually evaluated for impairment					0	535
Balance, end of period: collectively evaluated for impairment					600	663
Real estate construction other
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	1,517	1,097	1,465	1,439
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit)	261	312	313	(30)
Balance, end of period	1,517	1,097	1,465	1,439	1,778	1,409
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					1,778	1,409
Real estate term owner occupied
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	2,354	2,285	2,358	1,657
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit)	(10)	314	(14)	942
Balance, end of period	2,354	2,285	2,358	1,657	2,344	2,599
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					2,344	2,599
Real estate term non-owner occupied
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	7,075	5,298	6,853	5,515
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit)	(60)	103	162	(114)
Balance, end of period	7,075	5,298	6,853	5,515	7,015	5,401
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					7,015	5,401
Real estate term other
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	774	670	819	628
Charge-Offs	0	0	(5)	0
Recoveries	0	0	0	0
Provision (benefit)	10	73	(30)	115
Balance, end of period	774	670	819	628	784	743
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					784	743
Consumer secured by 1st deeds of trust
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	327	346	313	264
Charge-Offs	(85)	(22)	(85)	(22)
Recoveries	0	0	2	0
Provision (benefit)	93	2	105	84
Balance, end of period	327	346	313	264	335	326
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					335	326
Consumer other
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	362	420	408	397
Charge-Offs	0	0	(17)	(1)
Recoveries	4	14	8	19
Provision (benefit)	(2)	(28)	(35)	(9)
Balance, end of period	362	420	408	397	364	406
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					364	406
Unallocated
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	1,309	1,510	1,396	1,493
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit)	(81)	(152)	(168)	(135)
Balance, end of period	$ 1,309	$ 1,510	$ 1,396	$ 1,493	1,228	1,358
Balance, end of period: Individually evaluated for impairment					0	0
Balance, end of period: collectively evaluated for impairment					$ 1,228	$ 1,358