Bank segment - Credit risk profile - summary (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Credit risk profile based on nonaccrual loans
Nonaccrual loans	$ 48,344	$ 46,035
Accruing loans 90 days or more past due	0	0
Total troubled debt restructuring loans not included above	26,030	22,246
Residential 1-4 family
Credit risk profile based on nonaccrual loans
Nonaccrual loans	21,056	20,554
Total troubled debt restructuring loans not included above	13,450	13,962
Commercial real estate
Credit risk profile based on nonaccrual loans
Nonaccrual loans	3,630	1,188
Total troubled debt restructuring loans not included above	0	0
Home equity line of credit
Credit risk profile based on nonaccrual loans
Nonaccrual loans	3,331	2,254
Total troubled debt restructuring loans not included above	3,400	2,467
Residential land
Credit risk profile based on nonaccrual loans
Nonaccrual loans	693	970
Total troubled debt restructuring loans not included above	3,760	4,713
Commercial construction
Credit risk profile based on nonaccrual loans
Nonaccrual loans	0	0
Total troubled debt restructuring loans not included above	0	0
Residential construction
Credit risk profile based on nonaccrual loans
Nonaccrual loans	0	0
Total troubled debt restructuring loans not included above	0	0
Commercial loans
Credit risk profile based on nonaccrual loans
Nonaccrual loans	18,827	20,174
Total troubled debt restructuring loans not included above	5,420	1,104
Consumer loans
Credit risk profile based on nonaccrual loans
Nonaccrual loans	807	895
Total troubled debt restructuring loans not included above	$ 0	$ 0

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

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- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5111-111524

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- Definition

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