Portfolio loans and allowance for loan losses - Analysis of loans past due and still accruing or non-accrual status (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loans past due
90+Days	$ 1,540	$ 1,611
Non-accrual Loans	25,672	27,896
30 to 59 Days
Loans past due
Loans past due, still accruing	8,754	8,820
60 to 89 Days
Loans past due
Loans past due, still accruing	1,396	5,451
Commercial
Loans past due
90+Days		199
Non-accrual Loans	7,392	9,096
Commercial | 30 to 59 Days
Loans past due
Loans past due, still accruing	1,047	1,075
Commercial | 60 to 89 Days
Loans past due
Loans past due, still accruing		1,014
Commercial real estate
Loans past due
90+Days	159	584
Non-accrual Loans	8,941	9,178
Commercial real estate | 30 to 59 Days
Loans past due
Loans past due, still accruing	690	2,653
Commercial real estate | 60 to 89 Days
Loans past due
Loans past due, still accruing	387	3,121
Real estate construction
Loans past due
Non-accrual Loans	282	630
Real estate construction | 30 to 59 Days
Loans past due
Loans past due, still accruing		19
Retail Real Estate
Loans past due
90+Days	1,287	828
Non-accrual Loans	8,971	8,935
Retail Real Estate | 30 to 59 Days
Loans past due
Loans past due, still accruing	6,910	5,021
Retail Real Estate | 60 to 89 Days
Loans past due
Loans past due, still accruing	997	1,248
Retail Other
Loans past due
90+Days	94
Non-accrual Loans	86	57
Retail Other | 30 to 59 Days
Loans past due
Loans past due, still accruing	107	52
Retail Other | 60 to 89 Days
Loans past due
Loans past due, still accruing	$ 12	$ 68