Bank segment - Credit risk profile - payment activity (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Credit risk profile based on payment activity for loans
Total past due	$ 20,860	$ 23,102
Current	4,726,896	4,720,517
Total financing receivables	4,747,756	4,743,619
Recorded Investment greater than 90 days and accruing	0	0
Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	10,413	11,310
Current	2,051,136	2,036,741
Total financing receivables	2,061,549	2,048,051
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	2,416
Current	808,900	797,979
Total financing receivables	808,900	800,395
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	2,512	2,986
Current	880,623	860,177
Total financing receivables	883,135	863,163
Recorded Investment greater than 90 days and accruing	0	0
Residential land
Credit risk profile based on payment activity for loans
Total past due	305	255
Current	15,704	18,634
Total financing receivables	16,009	18,889
Recorded Investment greater than 90 days and accruing	0	0
Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
Current	116,548	126,768
Total financing receivables	116,548	126,768
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	10,759	16,080
Total financing receivables	10,759	16,080
Recorded Investment greater than 90 days and accruing	0	0
Commercial loans
Credit risk profile based on payment activity for loans
Total past due	3,196	2,226
Current	646,461	689,825
Total financing receivables	649,657	692,051
Recorded Investment greater than 90 days and accruing	0	0
Consumer loans
Credit risk profile based on payment activity for loans
Total past due	4,434	3,909
Current	196,765	174,313
Total financing receivables	201,199	178,222
Recorded Investment greater than 90 days and accruing	0	0
30-59 days past due
Credit risk profile based on payment activity for loans
Total past due	6,562	11,504
30-59 days past due \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	2,308	5,467
30-59 days past due \| Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	2,416
30-59 days past due \| Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	502	1,263
30-59 days past due \| Residential land
Credit risk profile based on payment activity for loans
Total past due	0	0
30-59 days past due \| Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
30-59 days past due \| Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
30-59 days past due \| Commercial loans
Credit risk profile based on payment activity for loans
Total past due	1,486	413
30-59 days past due \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	2,266	1,945
60-89 days past due
Credit risk profile based on payment activity for loans
Total past due	5,107	4,230
60-89 days past due \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	2,694	2,338
60-89 days past due \| Commercial real estate
Credit risk profile based on payment activity for loans
Total past due	0	0
60-89 days past due \| Home equity line of credit
Credit risk profile based on payment activity for loans
Total past due	494	381
60-89 days past due \| Residential land
Credit risk profile based on payment activity for loans
Total past due	0	0
60-89 days past due \| Commercial construction
Credit risk profile based on payment activity for loans
Total past due	0	0
60-89 days past due \| Residential construction
Credit risk profile based on payment activity for loans
Total past due	0	0
60-89 days past due \| Commercial loans
Credit risk profile based on payment activity for loans
Total past due	614	510
60-89 days past due \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	1,305	1,001
Greater than 90 days
Credit risk profile based on payment activity for loans
Total past due	9,191	7,368
Greater than 90 days \| Residential 1-4 family
Credit risk profile based on payment activity for loans
Total past due	5,411	3,505
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	1,516	1,342
Greater than 90 days \| Residential land
Credit risk profile based on payment activity for loans
Total past due	305	255
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	1,096	1,303
Greater than 90 days \| Consumer loans
Credit risk profile based on payment activity for loans
Total past due	$ 863	$ 963

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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