Portfolio loans - Loans identified as impaired, segregated by category (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Loans identified as impaired
Unpaid Contractual Principal Balance	$ 28,533	$ 45,686
Recorded Investment with No Allowance	17,555	29,540
Recorded Investment with Allowance	4,551	7,539
Total Recorded Investment	22,106	37,079
Related Allowance	2,208	4,853
Average Recorded Investment	34,733	45,370
Collateral dependent loans secured by real estate or business assets	17,300
Commercial Loans
Loans identified as impaired
Unpaid Contractual Principal Balance	11,739	14,415
Recorded Investment with No Allowance	3,186	4,727
Recorded Investment with Allowance	3,077	5,026
Total Recorded Investment	6,263	9,753
Related Allowance	1,248	3,330
Average Recorded Investment	9,467	13,774
Commercial Real Estate Loans
Loans identified as impaired
Unpaid Contractual Principal Balance	10,847	14,487
Recorded Investment with No Allowance	9,105	9,883
Recorded Investment with Allowance	1,000	2,039
Total Recorded Investment	10,105	11,922
Related Allowance	486	1,049
Average Recorded Investment	13,583	16,678
Real Estate Construction
Loans identified as impaired
Unpaid Contractual Principal Balance	576	1,116
Recorded Investment with No Allowance	559	974
Total Recorded Investment	559	974
Average Recorded Investment	836	873
Retail Real Estate
Loans identified as impaired
Unpaid Contractual Principal Balance	5,371	15,581
Recorded Investment with No Allowance	4,705	13,898
Recorded Investment with Allowance	474	474
Total Recorded Investment	5,179	14,372
Related Allowance	474	474
Average Recorded Investment	10,817	14,003
Retail Other
Loans identified as impaired
Unpaid Contractual Principal Balance		87
Recorded Investment with No Allowance		58
Total Recorded Investment		58
Average Recorded Investment	$ 30	$ 42