Mortgage Servicing Rights - Schedule of Changes in Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Transfers And Servicing [Abstract]
Carrying value prior to policy change	$ 76,107	$ 32,070
Fair value impact of change in accounting policy		1,011
Carrying value at beginning of period	76,107	33,081
Capitalization	13,510	15,013
Change in fair value:
Due to pay-offs/pay-downs	(3,060)	(265)
Due to change in valuation inputs or assumptions	6,603	(236)
Carrying value at March 31	$ 93,160	$ 47,593

Servicing asset amortized value to fair value adjustment.

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- Definition

Servicing asset at fair value, changes in fair value due to pay-offs or pay-downs.

+ References

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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

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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
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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

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Amount of increase (decrease) in fair value from changes in the inputs, assumptions, or model used to calculate the fair value of the contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

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