Fair Value Measurements - Carrying Amount and Estimated Fair Values of Financial Assets and Liabilities (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt issuance cost net	$ 14.4	$ 18.5
Term Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt issuance cost net	$ 14.4	$ 18.5

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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