Fair Value Measurements - Summary of Carrying Amount and Fair Value (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	$ 345,780
Debt Instrument Fair Value	351,750
Term Loan Credit Agreement [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	1,192,253
Debt Instrument Fair Value	$ 1,203,242

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

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