Debt - Aggregate Fair Value and Carrying Value of Short-Term Debt (Detail) $ in Thousands	Sep. 30, 2017 USD ($)
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Related-party notes payable, short-term	$ 2,200
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Related-party notes payable, short-term	$ 2,200

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

No definition available.

Name:	us-gaap_ShorttermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant