Bank segment - Credit risk profile - payment activity (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Credit risk profile based on payment activity for loans
30-59 days past due	$ 9,569	$ 8,993
60-89 days past due	2,606	2,711
Greater than 90 days	14,085	13,798
Total past due	26,260	25,502
Current	4,515,373	4,415,487
Total financing receivables	4,541,633	4,440,989	$ 4,342,389
Recorded Investment greater than 90 days and accruing	0	0
Residential 1-4 family
Credit risk profile based on payment activity for loans
30-59 days past due	6,354	6,124
60-89 days past due	1,722	1,732
Greater than 90 days	11,852	12,632
Total past due	19,928	20,488
Current	2,042,530	2,023,717
Total financing receivables	2,062,458	2,044,205	2,030,337
Commercial real estate
Credit risk profile based on payment activity for loans
Current	618,113	531,917
Total financing receivables	618,113	531,917	502,356
Home equity line of credit
Credit risk profile based on payment activity for loans
30-59 days past due	1,192	1,341
60-89 days past due	81	501
Greater than 90 days	436	194
Total past due	1,709	2,036
Current	830,558	816,779
Total financing receivables	832,267	818,815	808,991
Residential land
Credit risk profile based on payment activity for loans
30-59 days past due	120
60-89 days past due	0
Greater than 90 days	415
Total past due	535
Current	16,834	16,240
Total financing receivables	17,369	16,240	16,935
Recorded Investment greater than 90 days and accruing	0
Commercial construction
Credit risk profile based on payment activity for loans
Current	80,230	96,438
Total financing receivables	80,230	96,438	87,461
Residential construction
Credit risk profile based on payment activity for loans
Current	14,318	18,961
Total financing receivables	14,318	18,961	18,699
Commercial loans
Credit risk profile based on payment activity for loans
30-59 days past due	546	699
60-89 days past due	312	145
Greater than 90 days	1,005	569
Total past due	1,863	1,413
Current	796,565	790,344
Total financing receivables	798,428	791,757	770,079
Recorded Investment greater than 90 days and accruing		0
Consumer loans
Credit risk profile based on payment activity for loans
30-59 days past due	1,357	829
60-89 days past due	491	333
Greater than 90 days	377	403
Total past due	2,225	1,565
Current	116,225	121,091
Total financing receivables	$ 118,450	122,656	$ 107,531
Recorded Investment greater than 90 days and accruing		$ 0

Financing receivables that are less than 60 days past due but more than 29 days past due.

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=35738203&loc=SL6953401-111524

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- Definition

Financing receivables that are less than 90 days past due but more than 59 days past due.

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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

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

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- Definition

Financing receivables that are current.

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- Definition

Financing receivables that are equal to or greater than 90 days past due.

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- Definition

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

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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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Article 5

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