Bank segment - Loan modifications (Details) - Troubled debt restructurings real estate loans $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020 USD ($) contract	Jun. 30, 2019 USD ($) contract	Jun. 30, 2020 USD ($) contract	Jun. 30, 2019 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	4	7	11	17
Outstanding recorded investment	$ 349	$ 2,922	$ 17,677	$ 4,265
Net increase in allowance	$ 3	$ 346	$ 4,586	$ 394
Real estate \| Residential 1-4 family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	1	1	9
Outstanding recorded investment	$ 0	$ 469	$ 147	$ 1,501
Net increase in allowance	$ 0	$ 154	$ 7	$ 161
Real estate \| Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	0	2	0
Outstanding recorded investment	$ 0	$ 0	$ 16,430	$ 0
Net increase in allowance	$ 0	$ 0	$ 4,301	$ 0
Real estate \| Home equity line of credit
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	2	2	2	3
Outstanding recorded investment	$ 19	$ 311	$ 19	$ 432
Net increase in allowance	$ 3	$ 59	$ 3	$ 83
Real estate \| Residential land
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	2	2	2	2
Outstanding recorded investment	$ 330	$ 825	$ 330	$ 825
Net increase in allowance	$ 0	$ 0	$ 0	$ 0
Real estate \| Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	0	0	0
Outstanding recorded investment	$ 0	$ 0	$ 0	$ 0
Net increase in allowance	$ 0	$ 0	$ 0	$ 0
Real estate \| Residential construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	0	0	0
Outstanding recorded investment	$ 0	$ 0	$ 0	$ 0
Net increase in allowance	$ 0	$ 0	$ 0	$ 0
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	2	4	3
Outstanding recorded investment	$ 0	$ 1,317	$ 751	$ 1,507
Net increase in allowance	$ 0	$ 133	$ 275	$ 150
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts \| contract	0	0	0	0
Outstanding recorded investment	$ 0	$ 0	$ 0	$ 0
Net increase in allowance	$ 0	$ 0	$ 0	$ 0

Amount of increase (decrease) of allowance reserve for credit loss.

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- Definition

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.

+ References

No definition available.

+ Details

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ 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, before troubled debt restructuring, of financing receivable to be modified.

+ References

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