Convertible and Long-Term Debt Obligations - Warehouse Agreements - Additional Information (Detail) $ in Millions	Feb. 06, 2018 USD ($)
Non-recourse debt [Member] \| Warehouse Agreements [Member]
Debt Instrument [Line Items]
Repayments of secured debt	$ 453.6

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

Name:	us-gaap_RepaymentsOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration