Debt - Schedule of Debt Restated for Adoption of New Accounting Standard (Parenthetical) (Detail) - USD ($)	Dec. 31, 2016	Oct. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Borrowings	$ 250,000,000
Senior Notes Due 2020 [Member] | Audited [Member]
Debt Instrument [Line Items]
Borrowings					$ 250,000,000
Senior Notes Due 2020 [Member] | Restated [Member]
Debt Instrument [Line Items]
Borrowings					250,000,000
Senior Secured Term Loan B [Member]
Debt Instrument [Line Items]
Borrowings	545,000,000		$ 545,000,000	$ 575,000,000
Senior Secured Term Loan B [Member] | Audited [Member]
Debt Instrument [Line Items]
Borrowings					575,000,000
Senior Secured Term Loan B [Member] | Restated [Member]
Debt Instrument [Line Items]
Borrowings					575,000,000
Senior Secured Revolving Facility [Member]
Debt Instrument [Line Items]
Borrowings	$ 143,000,000	$ 143,000,000	$ 133,000,000	$ 100,000,000
Senior Secured Revolving Facility [Member] | Audited [Member]
Debt Instrument [Line Items]
Borrowings					100,000,000
Senior Secured Revolving Facility [Member] | Restated [Member]
Debt Instrument [Line Items]
Borrowings					100,000,000
ASU 2015-13 Reclass [Member] | Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Borrowings					250,000,000
ASU 2015-13 Reclass [Member] | Senior Secured Term Loan B [Member]
Debt Instrument [Line Items]
Borrowings					575,000,000
ASU 2015-13 Reclass [Member] | Senior Secured Revolving Facility [Member]
Debt Instrument [Line Items]
Borrowings					$ 100,000,000