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Warehouse Notes Payable - Schedule of Company Lines Available and Borrowings Outstanding (Parenthetical) (Detail) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
May 12, 2018 | Mar. 31, 2018 | Dec. 31, 2017
Warehouse Line Due June 20, 2018 [Member] |  |  |
Securities Financing Transaction [Line Items] |  |  |
Maturity date |  | Jun. 20, 2018 | Jun. 20, 2018
Warehouse Line Due September 25, 2018 [Member] |  |  |
Securities Financing Transaction [Line Items] |  |  |
Maturity date |  | Sep. 25, 2018 | Sep. 25, 2018
Warehouse Line Due October 11, 2018 [Member] |  |  |
Securities Financing Transaction [Line Items] |  |  |
Maturity date |  | Oct. 11, 2018 | Oct. 11, 2018
Warehouse Line Due October 11, 2018 [Member] | Scenario, Forecast [Member] |  |  |
Securities Financing Transaction [Line Items] |  |  |
Lines available | $ 400.0 |  |
Warehouse line increase | $ 300.0 |  |

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- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer. + References No definition available. + Details
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- Definition Amount of increase (decrease) of the credit facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(f)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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