Bank segment - Credit risk profile - payment activity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Credit risk profile based on payment activity for loans
Total financing receivables	$ 5,133,584	$ 5,345,226
Amortized cost> 90 days and accruing	0	0
Real estate
Credit risk profile based on payment activity for loans
Total financing receivables	4,252,590	4,239,745
Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	2,172,073	2,144,239
Amortized cost> 90 days and accruing	0	0
Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	1,090,816	983,865
Amortized cost> 90 days and accruing	0	0
Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	851,416	963,578
Amortized cost> 90 days and accruing	0	0
Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	19,399	15,617
Amortized cost> 90 days and accruing	0	0
Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	109,716	121,424
Amortized cost> 90 days and accruing	0	0
Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	9,170	11,022
Amortized cost> 90 days and accruing	0	0
Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	758,338	936,748
Amortized cost> 90 days and accruing	0	0
Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	122,656	168,733
Amortized cost> 90 days and accruing	0	0
30-59 days past due
Credit risk profile based on payment activity for loans
Total financing receivables	4,940	7,394
30-59 days past due | Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	2,224	2,629
30-59 days past due | Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
30-59 days past due | Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	255	850
30-59 days past due | Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	97	702
30-59 days past due | Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
30-59 days past due | Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
30-59 days past due | Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	937	608
30-59 days past due | Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	1,427	2,605
60-89 days past due
Credit risk profile based on payment activity for loans
Total financing receivables	2,640	5,411
60-89 days past due | Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	1,584	2,790
60-89 days past due | Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	0	488
60-89 days past due | Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	208	342
60-89 days past due | Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
60-89 days past due | Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
60-89 days past due | Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
60-89 days past due | Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	68	300
60-89 days past due | Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	780	1,491
Greater than 90 days
Credit risk profile based on payment activity for loans
Total financing receivables	11,467	6,830
Greater than 90 days | Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	8,552	2,715
Greater than 90 days | Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
Greater than 90 days | Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	1,455	2,052
Greater than 90 days | Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	300	300
Greater than 90 days | Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
Greater than 90 days | Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
Greater than 90 days | Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	110	132
Greater than 90 days | Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	1,050	1,631
Total past due
Credit risk profile based on payment activity for loans
Total financing receivables	19,047	19,635
Total past due | Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	12,360	8,134
Total past due | Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	0	488
Total past due | Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	1,918	3,244
Total past due | Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	397	1,002
Total past due | Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
Total past due | Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	0	0
Total past due | Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	1,115	1,040
Total past due | Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	3,257	5,727
Current
Credit risk profile based on payment activity for loans
Total financing receivables	5,114,537	5,325,591
Current | Real estate | Residential 1-4 family
Credit risk profile based on payment activity for loans
Total financing receivables	2,159,713	2,136,105
Current | Real estate | Commercial real estate
Credit risk profile based on payment activity for loans
Total financing receivables	1,090,816	983,377
Current | Real estate | Home equity line of credit
Credit risk profile based on payment activity for loans
Total financing receivables	849,498	960,334
Current | Real estate | Residential land
Credit risk profile based on payment activity for loans
Total financing receivables	19,002	14,615
Current | Real estate | Commercial construction
Credit risk profile based on payment activity for loans
Total financing receivables	109,716	121,424
Current | Real estate | Residential construction
Credit risk profile based on payment activity for loans
Total financing receivables	9,170	11,022
Current | Commercial
Credit risk profile based on payment activity for loans
Total financing receivables	757,223	935,708
Current | Consumer
Credit risk profile based on payment activity for loans
Total financing receivables	$ 119,399	$ 163,006