Loans Receivable - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Classified loans	$ 1,059,595	$ 1,002,260
Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	1,044,700	987,967
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	7,923	7,763
Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	6,972	6,530
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Classified loans	426,887	407,844
Residential | Real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	424,626	405,532
Residential | Real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	118
Residential | Real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	2,261	2,194
Residential | Real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Commercial
Financing Receivable, Recorded Investment [Line Items]
Classified loans	124,436	122,264
Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	119,494	117,670
Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	3,839	3,844
Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	1,103	750
Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Commercial | Real estate
Financing Receivable, Recorded Investment [Line Items]
Classified loans	297,891	278,691
Commercial | Real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	292,342	274,247
Commercial | Real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	4,084	2,958
Commercial | Real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	1,465	1,486
Commercial | Real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Construction | Real estate
Financing Receivable, Recorded Investment [Line Items]
Classified loans	169,225	157,586
Construction | Real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	167,082	154,643
Construction | Real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	843
Construction | Real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	2,143	2,100
Construction | Real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Credit card
Financing Receivable, Recorded Investment [Line Items]
Classified loans	40,141	34,673
Consumer | Credit card | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	40,141	34,673
Consumer | Credit card | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Credit card | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Credit card | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Other consumer
Financing Receivable, Recorded Investment [Line Items]
Classified loans	1,015	1,202
Consumer | Other consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Classified loans	1,015	1,202
Consumer | Other consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Other consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Classified loans	0	0
Consumer | Other consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Classified loans	$ 0	$ 0