Bank segment - Principal balance of impaired loans (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2019
Recorded investment:
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	$ 18,397	$ 17,610
With an allowance recorded	29,395	29,240
Average recorded investment	47,792	46,850
Interest income recognized:
With no related allowance recorded	470	833
With an allowance recorded	288	826
Interest income recognized	758	1,659
Real estate | Residential 1-4 family
Recorded investment:
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	8,562	8,515
With an allowance recorded	8,296	8,377
Average recorded investment	16,858	16,892
Interest income recognized:
With no related allowance recorded	175	422
With an allowance recorded	86	265
Interest income recognized	261	687
Real estate | Commercial real estate
Recorded investment:
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	881	894
Average recorded investment	881	894
Interest income recognized:
With no related allowance recorded	0	0
With an allowance recorded	9	28
Interest income recognized	9	28
Real estate | Home equity line of credit
Recorded investment:
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	1,797	2,091
With an allowance recorded	11,332	11,606
Average recorded investment	13,129	13,697
Interest income recognized:
With no related allowance recorded	12	78
With an allowance recorded	143	425
Interest income recognized	155	503
Real estate | Residential land
Recorded investment:
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	3,205	2,507
With an allowance recorded	0	36
Average recorded investment	3,205	2,543
Interest income recognized:
With no related allowance recorded	40	90
With an allowance recorded	0	0
Interest income recognized	40	90
Real estate | Commercial construction
Recorded investment:
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:
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:
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	4,812	4,470
With an allowance recorded	8,330	8,026
Average recorded investment	13,142	12,496
Interest income recognized:
With no related allowance recorded	239	239
With an allowance recorded	38	94
Interest income recognized	277	333
Consumer
Recorded investment:
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	21	27
With an allowance recorded	556	301
Average recorded investment	577	328
Interest income recognized:
With no related allowance recorded	4	4
With an allowance recorded	12	14
Interest income recognized	$ 16	$ 18