Loans Receivable - Age analysis of past due loans and leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Age Analysis of Past Due Loans and Leases
Total past due	$ 2,048	$ 5,043
Current	1,014,792	958,221
Total Accruing Loans and leases	1,016,840	963,264
Nonaccrual loans and leases	6,595	3,235
Loans and Leases Receivable, Gross, Total	$ 1,023,435	$ 966,499
Delinquency percentage	0.84%	0.86%
Loans at fair value	$ 10,553	$ 10,546
Commercial mortgage
Age Analysis of Past Due Loans and Leases
Total past due	58
Current	390,544	361,857
Total Accruing Loans and leases	390,602	361,857
Nonaccrual loans and leases	726	733
Loans and Leases Receivable, Gross, Total	$ 391,328	$ 362,590
Delinquency percentage	0.20%	0.20%
Home equity lines and loans
Age Analysis of Past Due Loans and Leases
Total past due	$ 50
Current	77,953	$ 81,046
Total Accruing Loans and leases	78,003	81,046
Nonaccrual loans and leases	761	537
Loans and Leases Receivable, Gross, Total	$ 78,764	$ 81,583
Delinquency percentage	1.03%	0.66%
Residential mortgage
Age Analysis of Past Due Loans and Leases
Total past due	$ 1,487	$ 4,675
Current	46,473	47,446
Total Accruing Loans and leases	47,960	52,121
Nonaccrual loans and leases	4,694	1,544
Loans and Leases Receivable, Gross, Total	$ 52,654	$ 53,665
Delinquency percentage	11.74%	11.59%
Loans at fair value	$ 10,553	$ 10,546
Construction
Age Analysis of Past Due Loans and Leases
Total past due	233
Current	175,131	172,044
Total Accruing Loans and leases	175,364	172,044
Loans and Leases Receivable, Gross, Total	$ 175,364	172,044
Delinquency percentage	0.13%
Commercial and industrial
Age Analysis of Past Due Loans and Leases
Total past due	$ 125	206
Current	291,884	272,674
Total Accruing Loans and leases	292,009	272,880
Nonaccrual loans and leases	414	421
Loans and Leases Receivable, Gross, Total	$ 292,423	$ 273,301
Delinquency percentage	0.18%	0.23%
Small Business Loans
Age Analysis of Past Due Loans and Leases
Current	$ 31,773	$ 21,616
Total Accruing Loans and leases	31,773	21,616
Loans and Leases Receivable, Gross, Total	31,773	21,616
Consumer
Age Analysis of Past Due Loans and Leases
Current	570	1,003
Total Accruing Loans and leases	570	1,003
Loans and Leases Receivable, Gross, Total	570	1,003
Leases
Age Analysis of Past Due Loans and Leases
Total past due	95	162
Current	464	535
Total Accruing Loans and leases	559	697
Loans and Leases Receivable, Gross, Total	$ 559	$ 697
Delinquency percentage	16.99%	23.24%
Current | Residential mortgage
Age Analysis of Past Due Loans and Leases
Loans at fair value	$ 10,553	$ 9,056
30-89 days past due
Age Analysis of Past Due Loans and Leases
Total past due	2,028	5,043
30-89 days past due | Commercial mortgage
Age Analysis of Past Due Loans and Leases
Total past due	58
30-89 days past due | Home equity lines and loans
Age Analysis of Past Due Loans and Leases
Total past due	50
30-89 days past due | Residential mortgage
Age Analysis of Past Due Loans and Leases
Total past due	1,487	4,675
Loans at fair value	0	786
30-89 days past due | Construction
Age Analysis of Past Due Loans and Leases
Total past due	233
30-89 days past due | Commercial and industrial
Age Analysis of Past Due Loans and Leases
Total past due	125	206
30-89 days past due | Leases
Age Analysis of Past Due Loans and Leases
Total past due	75	162
90+days past due and still accruing
Age Analysis of Past Due Loans and Leases
Total past due	20
90+days past due and still accruing | Leases
Age Analysis of Past Due Loans and Leases
Total past due	20
Nonaccrual | Residential mortgage
Age Analysis of Past Due Loans and Leases
Loans at fair value	$ 0	$ 704