Loans and Allowance for Loan Losses - Loans by risk category (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Loans outstanding by loan portfolio segment and risk category
Loans	$ 1,937,345	$ 1,979,375
Pass
Loans outstanding by loan portfolio segment and risk category
Loans	1,881,791	1,922,704
Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	10,675	15,326
Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	44,698	41,345
Doubtful
Loans outstanding by loan portfolio segment and risk category
Loans	181
Commercial
Loans outstanding by loan portfolio segment and risk category
Loans	1,287,953	1,299,316
Commercial | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	1,239,986	1,247,786
Commercial | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	6,340	12,101
Commercial | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	41,446	39,429
Commercial | Doubtful
Loans outstanding by loan portfolio segment and risk category
Loans	181
Commercial | Commercial and industrial
Loans outstanding by loan portfolio segment and risk category
Loans	678,029	691,858
Commercial | Commercial and industrial | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	658,607	669,602
Commercial | Commercial and industrial | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	2,725	5,415
Commercial | Commercial and industrial | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	16,516	16,841
Commercial | Commercial and industrial | Doubtful
Loans outstanding by loan portfolio segment and risk category
Loans	181
Commercial | Real estate construction
Loans outstanding by loan portfolio segment and risk category
Loans	40,473	44,451
Commercial | Real estate construction | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	40,473	44,451
Commercial | Commercial real estate
Loans outstanding by loan portfolio segment and risk category
Loans	569,451	563,007
Commercial | Commercial real estate | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	540,906	533,733
Commercial | Commercial real estate | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	3,615	6,686
Commercial | Commercial real estate | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	24,930	22,588
Consumer
Loans outstanding by loan portfolio segment and risk category
Loans	649,392	680,059
Consumer | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	641,805	674,918
Consumer | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	4,335	3,225
Consumer | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	3,252	1,916
Consumer | Residential | Real estate first mortgage
Loans outstanding by loan portfolio segment and risk category
Loans	454,958	463,370
Consumer | Residential | Real estate first mortgage | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	448,919	461,221
Consumer | Residential | Real estate first mortgage | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	3,928	1,406
Consumer | Residential | Real estate first mortgage | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	2,111	743
Consumer | Residential | Real estate junior lien
Loans outstanding by loan portfolio segment and risk category
Loans	130,299	143,416
Consumer | Residential | Real estate junior lien | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	128,788	140,461
Consumer | Residential | Real estate junior lien | Special Mention
Loans outstanding by loan portfolio segment and risk category
Loans	407	1,819
Consumer | Residential | Real estate junior lien | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	1,104	1,136
Consumer | Other revolving and installment
Loans outstanding by loan portfolio segment and risk category
Loans	64,135	73,273
Consumer | Other revolving and installment | Pass
Loans outstanding by loan portfolio segment and risk category
Loans	64,098	73,236
Consumer | Other revolving and installment | Substandard
Loans outstanding by loan portfolio segment and risk category
Loans	$ 37	$ 37