Bank segment - Credit risk profile - nonaccrual loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Credit risk profile based on nonaccrual loans
With a Related ACL	$ 42,716	$ 36,491
Without a Related ACL	10,620	10,905
Total	53,336	47,396
Total troubled debt restructuring loans not included above	25,963	27,078
Real estate \| Residential 1-4 family
Credit risk profile based on nonaccrual loans
With a Related ACL	16,945	8,991
Without a Related ACL	2,987	2,835
Total	19,932	11,826
Total troubled debt restructuring loans not included above	7,453	7,932
Real estate \| Commercial real estate
Credit risk profile based on nonaccrual loans
With a Related ACL	15,634	15,847
Without a Related ACL	2,828	2,875
Total	18,462	18,722
Total troubled debt restructuring loans not included above	3,254	3,281
Real estate \| Home equity line of credit
Credit risk profile based on nonaccrual loans
With a Related ACL	5,075	5,791
Without a Related ACL	1,587	1,567
Total	6,662	7,358
Total troubled debt restructuring loans not included above	7,727	8,148
Real estate \| Residential land
Credit risk profile based on nonaccrual loans
With a Related ACL	107	108
Without a Related ACL	300	300
Total	407	408
Total troubled debt restructuring loans not included above	1,738	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	1,763	1,819
Without a Related ACL	2,918	3,328
Total	4,681	5,147
Total troubled debt restructuring loans not included above	5,737	6,108
Consumer
Credit risk profile based on nonaccrual loans
With a Related ACL	3,192	3,935
Without a Related ACL	0	0
Total	3,192	3,935
Total troubled debt restructuring loans not included above	$ 54	$ 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=121611835&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=121599337&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
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-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

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