Bank segment - Credit risk profile - payment activity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Credit risk profile based on payment activity for loans
Total past due	$ 24,178	$ 26,099
Current	4,715,595	4,595,969
Total financing receivables	4,739,773	4,622,068
Recorded Investment greater than 90 days and accruing	393	0
Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	16,495	19,759
Current	2,037,965	2,049,906
Total financing receivables	2,054,460	2,069,665
Recorded Investment greater than 90 days and accruing	0	0
Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	0
Current	774,349	690,561
Total financing receivables	774,349	690,561
Recorded Investment greater than 90 days and accruing	0	0
Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	2,288	2,079
Current	857,664	844,215
Total financing receivables	859,952	846,294
Recorded Investment greater than 90 days and accruing	0	0
Residential land
Credit risk profile based on payment activity for loans
Total past due	541	415
Current	19,125	17,814
Total financing receivables	19,666	18,229
Recorded Investment greater than 90 days and accruing	393	0
Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
Current	140,758	100,796
Total financing receivables	140,758	100,796
Recorded Investment greater than 90 days and accruing	0	0
Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
Current	15,073	14,089
Total financing receivables	15,073	14,089
Recorded Investment greater than 90 days and accruing	0	0
Commercial loans
Credit risk profile based on payment activity for loans
Total past due	1,697	1,226
Current	715,753	757,433
Total financing receivables	717,450	758,659
Recorded Investment greater than 90 days and accruing	0	0
Consumer loans
Credit risk profile based on payment activity for loans
Total past due	3,157	2,620
Current	154,908	121,155
Total financing receivables	158,065	123,775
Recorded Investment greater than 90 days and accruing	0	0
30 to 59 days past due
Credit risk profile based on payment activity for loans
Total past due	7,509	7,371
30 to 59 days past due \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	4,293	4,967
30 to 59 days past due \| Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	0
30 to 59 days past due \| Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	827	896
30 to 59 days past due \| Residential land
Credit risk profile based on payment activity for loans
Total past due	0	0
30 to 59 days past due \| Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
30 to 59 days past due \| Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
30 to 59 days past due \| Commercial loans
Credit risk profile based on payment activity for loans
Total past due	681	125
30 to 59 days past due \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	1,708	1,383
60 to 89 days past due
Credit risk profile based on payment activity for loans
Total past due	4,046	4,811
60 to 89 days past due \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	1,626	3,289
60 to 89 days past due \| Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	0
60 to 89 days past due \| Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	787	706
60 to 89 days past due \| Residential land
Credit risk profile based on payment activity for loans
Total past due	0	0
60 to 89 days past due \| Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
60 to 89 days past due \| Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
60 to 89 days past due \| Commercial loans
Credit risk profile based on payment activity for loans
Total past due	997	223
60 to 89 days past due \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	636	593
Greater than 90 days
Credit risk profile based on payment activity for loans
Total past due	12,623	13,917
Greater than 90 days \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	10,576	11,503
Greater than 90 days \| Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	0
Greater than 90 days \| Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	674	477
Greater than 90 days \| Residential land
Credit risk profile based on payment activity for loans
Total past due	541	415
Greater than 90 days \| Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
Greater than 90 days \| Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
Greater than 90 days \| Commercial loans
Credit risk profile based on payment activity for loans
Total past due	19	878
Greater than 90 days \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	$ 813	$ 644

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

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

Financing receivables that are current.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

+ 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 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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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.

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- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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