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Disclosures about Fair Value of Financial Instruments - Narrative (Detail) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2017 | Jun. 30, 2017 | Jun. 26, 2014 | Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Loans held for sale, average life from purchase to sale (days) | 22 days |  |  |
Senior Notes |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Senior unsecured notes aggregate amount |  | $ 100,000,000 | $ 25,000,000.0 |
Senior Notes Due 2018 | Senior Notes |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Senior unsecured notes term (years) | 5 years |  |  |
Senior unsecured notes aggregate amount |  |  |  | $ 63,300,000.0

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
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- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + 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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