Loans and Credit Quality - Aging Analysis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	$ 59,368	$ 64,358
Current	5,304,211	5,029,389
Total loans	5,363,579	5,093,747
90-days or more past due and still accruing	29,273	39,116
Fair value of loans held for investment	4,830	4,057
Recurring [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Fair value of loans held for investment	4,830	4,057
Level 3 [Member] | Recurring [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Fair value of loans held for investment	4,830	4,057
30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	6,670	9,870
60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	7,551	3,753
90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	45,147	50,735
Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	50,161	62,180
Current	1,883,560	1,866,918
Total loans	1,933,721	1,929,098
90-days or more past due and still accruing	29,273	39,116
Consumer loans [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	6,526	9,870
Consumer loans [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	5,513	3,753
Consumer loans [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	38,122	48,557
Consumer loans [Member] | Single family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	48,443	60,987
Current	1,300,111	1,297,188
Total loans	1,348,554	1,358,175
90-days or more past due and still accruing	29,273	39,116
Consumer loans [Member] | Single family [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	5,872	9,725
Consumer loans [Member] | Single family [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	5,416	3,653
Consumer loans [Member] | Single family [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	37,155	47,609
Consumer loans [Member] | Home equity and other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,718	1,193
Current	583,449	569,730
Total loans	585,167	570,923
90-days or more past due and still accruing	0	0
Consumer loans [Member] | Home equity and other [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	654	145
Consumer loans [Member] | Home equity and other [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	97	100
Consumer loans [Member] | Home equity and other [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	967	948
Commercial real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,901	72
Current	2,552,973	2,404,415
Total loans	2,557,874	2,404,487
90-days or more past due and still accruing	0	0
Commercial real estate loans [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	144	0
Commercial real estate loans [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,757	72
Commercial real estate loans [Member] | Non-owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	11	0
Current	780,928	701,928
Total loans	780,939	701,928
90-days or more past due and still accruing	0	0
Commercial real estate loans [Member] | Non-owner occupied commercial real estate [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Non-owner occupied commercial real estate [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Non-owner occupied commercial real estate [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	11	0
Commercial real estate loans [Member] | Multifamily [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	144	0
Current	939,512	908,015
Total loans	939,656	908,015
90-days or more past due and still accruing	0	0
Commercial real estate loans [Member] | Multifamily [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	144	0
Commercial real estate loans [Member] | Multifamily [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Multifamily [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Construction/land development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,746	72
Current	832,533	794,472
Total loans	837,279	794,544
90-days or more past due and still accruing	0	0
Commercial real estate loans [Member] | Construction/land development [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Construction/land development [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial real estate loans [Member] | Construction/land development [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,746	72
Commercial and industrial loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,306	2,106
Current	867,678	758,056
Total loans	871,984	760,162
90-days or more past due and still accruing	0	0
Commercial and industrial loans [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial and industrial loans [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,038	0
Commercial and industrial loans [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,268	2,106
Commercial and industrial loans [Member] | Owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,402	374
Current	448,048	428,784
Total loans	450,450	429,158
90-days or more past due and still accruing	0	0
Commercial and industrial loans [Member] | Owner occupied commercial real estate [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial and industrial loans [Member] | Owner occupied commercial real estate [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,038	0
Commercial and industrial loans [Member] | Owner occupied commercial real estate [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	364	374
Commercial and industrial loans [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,904	1,732
Current	419,630	329,272
Total loans	421,534	331,004
90-days or more past due and still accruing	0	0
Commercial and industrial loans [Member] | Commercial business [Member] | 30 to 59 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial and industrial loans [Member] | Commercial business [Member] | 60 to 89 days past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	0	0
Commercial and industrial loans [Member] | Commercial business [Member] | 90 days or more past due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	$ 1,904	$ 1,732