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Fair Value Measurements - Quantitative and Qualitative Information (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	$ 8,131	$ 6,944
Measurement Input, Discount Rate
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value		$ 6,944
Measurement Input, Discount Rate | Minimum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input		10.0
Measurement Input, Discount Rate | Maximum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input		34.3
Measurement Input, Discount Rate | Weighted Average
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input		10.2
Recurring | Measurement Input, Discount Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	$ 8,131
Recurring | Measurement Input, Discount Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Minimum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	7.0
Recurring | Measurement Input, Discount Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Maximum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	302.1
Recurring | Measurement Input, Discount Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Weighted Average
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	10.2
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Minimum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	7.0	7.0
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Maximum
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	68.9	68.4
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage servicing rights | Discounted Cash Flow | Level 3 | Weighted Average
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	8.2	9.6

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- Definition

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+ References

No definition available.

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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746

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- Definition

Value of input used to measure servicing asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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