Bank segment - Principal balance of impaired loans (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2019
Recorded investment:
With no related allowance recorded			$ 14,037
With an allowance recorded			26,700
Recorded investment			40,737
Unpaid principal balance:
With no related allowance recorded			15,123
With an allowance recorded			26,762
Unpaid principal balance			41,885
Related Allowance			2,691
Average recorded investment:
With no related allowance recorded	$ 17,870	$ 17,218
With an allowance recorded	32,363	29,161
Average recorded investment	50,233	46,379
Interest income recognized:
With no related allowance recorded	165	363
With an allowance recorded	288	538
Interest income recognized	453	901
Real estate | Residential 1-4 family
Recorded investment:
With no related allowance recorded			6,817
With an allowance recorded			8,783
Recorded investment			15,600
Unpaid principal balance:
With no related allowance recorded			7,207
With an allowance recorded			8,835
Unpaid principal balance			16,042
Related Allowance			898
Average recorded investment:
With no related allowance recorded	8,993	8,492
With an allowance recorded	8,440	8,417
Average recorded investment	17,433	16,909
Interest income recognized:
With no related allowance recorded	87	247
With an allowance recorded	96	179
Interest income recognized	183	426
Real estate | Commercial real estate
Recorded investment:
With no related allowance recorded			195
With an allowance recorded			853
Recorded investment			1,048
Unpaid principal balance:
With no related allowance recorded			200
With an allowance recorded			853
Unpaid principal balance			1,053
Related Allowance			2
Average recorded investment:
With no related allowance recorded	0	0
With an allowance recorded	894	900
Average recorded investment	894	900
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	9	19
Interest income recognized	9	19
Real estate | Home equity line of credit
Recorded investment:
With no related allowance recorded			1,984
With an allowance recorded			10,089
Recorded investment			12,073
Unpaid principal balance:
With no related allowance recorded			2,135
With an allowance recorded			10,099
Unpaid principal balance			12,234
Related Allowance			322
Average recorded investment:
With no related allowance recorded	1,940	2,238
With an allowance recorded	11,665	11,743
Average recorded investment	13,605	13,981
Interest income recognized:
With no related allowance recorded	54	66
With an allowance recorded	152	282
Interest income recognized	206	348
Real estate | Residential land
Recorded investment:
With no related allowance recorded			3,091
With an allowance recorded			0
Recorded investment			3,091
Unpaid principal balance:
With no related allowance recorded			3,294
With an allowance recorded			0
Unpaid principal balance			3,294
Related Allowance			0
Average recorded investment:
With no related allowance recorded	2,280	2,158
With an allowance recorded	79	54
Average recorded investment	2,359	2,212
Interest income recognized:
With no related allowance recorded	24	50
With an allowance recorded	0	0
Interest income recognized	24	50
Real estate | Commercial construction
Recorded investment:
With no related allowance recorded			0
With an allowance recorded			0
Recorded investment			0
Unpaid principal balance:
With no related allowance recorded			0
With an allowance recorded			0
Unpaid principal balance			0
Related Allowance			0
Average recorded investment:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Average recorded investment	0	0
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Interest income recognized	0	0
Real estate | Residential construction
Recorded investment:
With no related allowance recorded			0
With an allowance recorded			0
Recorded investment			0
Unpaid principal balance:
With no related allowance recorded			0
With an allowance recorded			0
Unpaid principal balance			0
Related Allowance			0
Average recorded investment:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Average recorded investment	0	0
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	0	0
Interest income recognized	0	0
Commercial
Recorded investment:
With no related allowance recorded			1,948
With an allowance recorded			6,470
Recorded investment			8,418
Unpaid principal balance:
With no related allowance recorded			2,285
With an allowance recorded			6,470
Unpaid principal balance			8,755
Related Allowance			1,015
Average recorded investment:
With no related allowance recorded	4,626	4,299
With an allowance recorded	10,997	7,874
Average recorded investment	15,623	12,173
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	30	56
Interest income recognized	30	56
Consumer
Recorded investment:
With no related allowance recorded			2
With an allowance recorded			505
Recorded investment			507
Unpaid principal balance:
With no related allowance recorded			2
With an allowance recorded			505
Unpaid principal balance			507
Related Allowance			$ 454
Average recorded investment:
With no related allowance recorded	31	31
With an allowance recorded	288	173
Average recorded investment	319	204
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	1	2
Interest income recognized	$ 1	$ 2