Composition of loans receivable and allowance for loan losses - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Allowance For Loan And Lease Losses Collectively Evaluated Loans [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	$ 347,701	$ 340,847
Residential 5+ multifamily	34,913	34,478
Construction of residential 1-4 family	11,899	11,889
Home equity lines of credit	28,662	33,693
Residential real estate	423,175	420,907
Commercial	304,328	285,462
Construction of commercial	24,687	8,466
Commercial real estate	329,015	293,928
Farm land	3,129	3,455
Vacant land	13,524	7,713
Real estate secured	768,843	726,003
Commercial and industrial	236,572	169,285
Municipal	20,797	21,914
Consumer	7,656	6,349
Unallocated allowance
Totals	1,033,868	923,551
SEC Schedule, 12-09, Allowance, Loan and Lease Loss, Real Estate [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	2,724	2,117
Residential 5+ multifamily	603	446
Construction of residential 1-4 family	97	75
Home equity lines of credit	261	197
Residential real estate	3,685	2,835
Commercial	5,194	3,333
Construction of commercial	400	104
Commercial real estate	5,594	3,437
Farm land	65	47
Vacant land	168	66
Real estate secured	9,512	6,385
Commercial and industrial	1,092	1,143
Municipal	41	46
Consumer	62	59
Unallocated allowance	1,226	569
Totals	11,933	8,202
Allowance For Loan And Lease Losses Individually Evaluated Loans [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	4,846	5,452
Residential 5+ multifamily	967	977
Construction of residential 1-4 family
Home equity lines of credit	233	105
Residential real estate	6,046	6,534
Commercial	4,397	4,333
Construction of commercial
Commercial real estate	4,397	4,333
Farm land	166	186
Vacant land	170	180
Real estate secured	10,779	11,233
Commercial and industrial	876	126
Municipal
Consumer	30	36
Unallocated allowance
Totals	11,685	11,395
SEC Schedule, 12-09, Allowance, Loan and Lease Loss [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	383	276
Residential 5+ multifamily
Construction of residential 1-4 family
Home equity lines of credit	14
Residential real estate	397	276
Commercial	270	409
Construction of commercial
Commercial real estate	270	409
Farm land
Vacant land	3	5
Real estate secured	670	690
Commercial and industrial	380	2
Municipal
Consumer	18	1
Unallocated allowance
Totals	1,068	693
Allowance For Loan And Lease Losses Total Portfolio Loans [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	352,547	346,299
Residential 5+ multifamily	35,880	35,455
Construction of residential 1-4 family	11,899	11,889
Home equity lines of credit	28,895	33,798
Residential real estate	429,221	427,441
Commercial	308,725	289,795
Construction of commercial	24,687	8,466
Commercial real estate	333,412	298,261
Farm land	3,295	3,641
Vacant land	13,694	7,893
Real estate secured	779,622	737,236
Commercial and industrial	237,448	169,411
Municipal	20,797	21,914
Consumer	7,686	6,385
Unallocated allowance
Totals	1,045,553	934,946
Allowance For Loan And Lease Losses Total Portfolio Allowance [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Residential 1-4 family	3,107	2,393
Residential 5+ multifamily	603	446
Construction of residential 1-4 family	97	75
Home equity lines of credit	275	197
Residential real estate	4,082	3,111
Commercial	5,464	3,742
Construction of commercial	400	104
Commercial real estate	5,864	3,846
Farm land	65	47
Vacant land	171	71
Real estate secured	10,182	7,075
Commercial and industrial	1,472	1,145
Municipal	41	46
Consumer	80	60
Unallocated allowance	1,226	569
Totals	$ 13,001	$ 8,895