Fair Value of Financial Instruments - Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market fund	$ 24.1	$ 13.7
Quoted Prices in Active Markets (Level 1) [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market fund	24.1	$ 13.7
Long-Term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	6.0
Long-Term Debt [Member] | Significant Unobservable (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 6.0