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Significant Unobservable Inputs used in Fair Value Measurement (Detail) - Mortgage servicing rights $ in Thousands | 6 Months Ended |  |  |
--- | --- | --- | --- | ---
Jun. 30, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jun. 30, 2017 USD ($) | Dec. 31, 2016 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Fair value |  | $ 2,505 | $ 2,729 | $ 220,586 | $ 228,099
Valuation Technique, Discounted Cash Flow [Member] |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Valuation Technique |  | Discounted Cash Flow |  |  |
Measurement Input, Constant Prepayment Rate [Member] |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Significant Unobservable Input Value | [1] | 0.1066 |  |  |
Measurement Input, Discount Rate [Member] |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Significant Unobservable Input Value |  | 0.1200 |  |  |
[1] | Represents annualized loan repayment rate assumptions.

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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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 + Details
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