Disclosures about Fair Value of Assets and Liabilities - Reconciliation of Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mortgage servicing rights
Reconciliation of significant unobservable inputs:
Balance, beginning of period	$ 53,670	$ 55,553	$ 52,913
Additions
Purchased servicing	1,209	1,357	1,135
Originated servicing	9,784	4,388	6,866
Acquisition of Richmac	3,970
Subtractions
Paydowns	(5,504)	(4,230)	(5,177)
Changes in fair value due to changes in valuation inputs or assumptions used in the valuation model	2,950	(3,398)	(184)
Balance, end of period	66,079	$ 53,670	$ 55,553
Municipals \| Available-for-sale Securities
Additions
Purchased securities	6,688
Subtractions
Balance, end of period	$ 6,688

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Amount of changes in fair value due to changes in valuation inputs or assumptions used in the valuation model.

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Amount of originated servicing classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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No definition available.

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Amount of purchased securities of classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchased servicing classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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No definition available.

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

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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