Mortgage Servicing Rights - At Amortized Cost (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Servicing Asset at Amortized Value, Balance [Roll Forward]
Servicing asset at fair value, ending	$ 18,457	$ 15,621
Mortgage loans
Servicing Asset at Amortized Value, Balance [Roll Forward]
Servicing asset at amortized cost, before valuation reserve, beginning	15,860	14,374	$ 14,018
Servicing Asset at Amortized Cost, Acquisitions	0	(306)	0
Originations of mortgage servicing rights	5,758	3,614	2,717
Amorization expense	(2,957)	(2,434)	(2,361)
Servicing asset at amortized cost, before valuation reserve, ending	18,661	15,860	14,374
Less valuation reserve	(204)	(239)	(336)
Servicing asset at fair value, ending	18,457	15,621	14,038
Principal balance of serviced loans underlying mortgage servicing rights	$ 3,127,528	$ 2,906,239	$ 2,615,311
Mortgage servicing rights as a percentage of serviced loans	0.0059	0.0054	0.0054

Servicing Asset As a Percentage of Serviced Loans Held-In-Portfolio

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- Definition

Servicing Asset at Amortized Cost, Before Valuation Reserve

+ References

No definition available.

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- Definition

Servicing Asset at Amortized Cost, Acquisitions

+ References

No definition available.

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- Definition

This is the result of the principal amount outstanding of total loans managed or securitized less securitized loans and loans that are in the process of being securitized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=64830801&loc=d3e107314-111719

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- Definition

Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7524895&loc=d3e120260-111741

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

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- Definition

Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

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- Definition

Amount of amortization of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

+ Details

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