Bank segment - Credit risk profile - nonaccrual loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Credit risk profile based on nonaccrual loans
With a Related ACL	$ 36,801	$ 36,491
Without a Related ACL	12,992	10,905
Total	49,793	47,396
Total troubled debt restructuring loans not included above	25,955	27,078
Real estate \| Residential 1-4 family
Credit risk profile based on nonaccrual loans
With a Related ACL	13,307	8,991
Without a Related ACL	7,997	2,835
Total	21,304	11,826
Total troubled debt restructuring loans not included above	7,545	7,932
Real estate \| Commercial real estate
Credit risk profile based on nonaccrual loans
With a Related ACL	15,062	15,847
Without a Related ACL	1,251	2,875
Total	16,313	18,722
Total troubled debt restructuring loans not included above	3,136	3,281
Real estate \| Home equity line of credit
Credit risk profile based on nonaccrual loans
With a Related ACL	4,564	5,791
Without a Related ACL	1,364	1,567
Total	5,928	7,358
Total troubled debt restructuring loans not included above	6,986	8,148
Real estate \| Residential land
Credit risk profile based on nonaccrual loans
With a Related ACL	97	108
Without a Related ACL	300	300
Total	397	408
Total troubled debt restructuring loans not included above	985	1,555
Real estate \| Commercial construction
Credit risk profile based on nonaccrual loans
With a Related ACL	0	0
Without a Related ACL	0	0
Total	0	0
Total troubled debt restructuring loans not included above	0	0
Real estate \| Residential construction
Credit risk profile based on nonaccrual loans
With a Related ACL	0	0
Without a Related ACL	0	0
Total	0	0
Total troubled debt restructuring loans not included above	0	0
Commercial
Credit risk profile based on nonaccrual loans
With a Related ACL	1,573	1,819
Without a Related ACL	2,080	3,328
Total	3,653	5,147
Total troubled debt restructuring loans not included above	7,251	6,108
Consumer
Credit risk profile based on nonaccrual loans
With a Related ACL	2,198	3,935
Without a Related ACL	0	0
Total	2,198	3,935
Total troubled debt restructuring loans not included above	$ 52	$ 54

Financing Receivable, Nonaccrual, With Allowance

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- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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- Definition

Amount of financing receivable on nonaccrual status with no allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

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Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (3)

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (2)

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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