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Mortgage Servicing Rights - Additional Information (Detail) - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016 | Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Mortgage servicing rights | $ 225,400,000 |  | $ 225,400,000 |  | $ 234,000,000
Mortgage Banking Income |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Contractually specified servicing fees, late fees, and ancillary fees earned in exchange for servicing financial assets | 352,000 | $ 322,000 | 663,000 | $ 632,000 |
Mortgage Receivable |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Unpaid principal balance of loans serviced for others | $ 24,800,000,000 |  | 24,800,000,000 |  | $ 25,100,000,000
Impairment of intangible assets |  |  | $ 0 | $ 0 |

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- Definition Amount of loans serviced for others. + References No definition available. + Details
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- Definition Amount of contractually specified servicing fee, late fee, and ancillary fee recognized as income for servicing asset and servicing liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746 + 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 The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
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- Definition Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 + Details
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- Details
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- Details
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