Share-Based Compensation - Summary of Total Stock Based Compensation Expense (Parenthetical) (Detail) - Former Chief Executive Officer [Member] $ in Millions	3 Months Ended
Mar. 31, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Forfeitures related stock-based compensation expense	$ 1.5
Separation agreement payment	$ 2.5

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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