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Changes in Residential and Participation Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items] |  |  |
Carrying value, beginning of year |  | $ 228,099 |
Carrying value, end of period |  | 2,729 | $ 228,099
Mortgage Servicing Rights Residential |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Carrying value, beginning of year |  | 228,099 | 243,389
Additions |  | 18,054 | 45,588
Sales |  | (208,827) |
Due to changes in interest rates |  | (2,096) | 3,341
Due to model assumption changes | [1] |  | (13,088)
Due to loan payoffs |  | (22,610) | (33,425)
Due to passage of time and other changes |  | (9,891) | (17,706)
Carrying value, end of period |  | 2,729 | 228,099
Mortgage Servicing Rights Participation |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Carrying value, beginning of year |  | 5,862 | 4,345
Additions |  | 710 | 3,774
Amortization |  | (3,201) | (2,257)
Carrying value, end of period |  | $ 3,371 | $ 5,862
[1] | Represents changes in fair value driven by changes to the inputs to the valuation model related to assumed prepayment speeds.

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- Definition Servicing Asset At Fair Value Loan Pay Offs + References No definition available. + Details
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- Definition Amount of increase (decrease) in fair value from changes in the assumptions or model used to calculate the fair value of a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References No definition available. + Details
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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 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 + Details
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- Definition The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
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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/presentationRef -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 + Details
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- Definition Amount of increase (decrease) in fair value from changes in the inputs used to calculate the fair value 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 3 -Subparagraph (a)(4)(i) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
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- Definition Decrease in servicing assets subsequently measured at fair value resulting from conveyance of servicing rights to unrelated parties. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
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- Definition Amount of increase (decrease) from changes in fair value classified as other for a 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 3 -Subparagraph (a)(4)(ii) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
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- Details
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