Schedule of Debt (Parenthetical) (Detail) - Senior Secured Debt - Term Loan - Debt instrument, maturing on June 15, 2024	6 Months Ended
Jan. 31, 2018
Debt Instrument [Line Items]
Loan maturity date	Jun. 15, 2024
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	2.75%

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration