Bank segment - Allowance for loan commitments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Allowance for loan commitments:
Beginning balance	$ 5,900	$ 3,650	$ 4,900	$ 4,300
Provision	(1,500)	250	(500)	(400)
Ending balance	4,400	3,900	4,400	3,900
Real estate \| Home equity line of credit
Allowance for loan commitments:
Beginning balance	400	400	400	300
Provision	0	0	0	100
Ending balance	400	400	400	400
Real estate \| Commercial construction
Allowance for loan commitments:
Beginning balance	4,100	2,400	3,700	3,000
Provision	(1,500)	300	(1,100)	(300)
Ending balance	2,600	2,700	2,600	2,700
Commercial
Allowance for loan commitments:
Beginning balance	1,400	850	800	1,000
Provision	0	(50)	600	(200)
Ending balance	$ 1,400	$ 800	$ 1,400	$ 800

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82919202-210446

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Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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