Share-Based Compensation - Unrecognized Compensation Expense (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 54,482
Stock options
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 12,756
Average Expected Recognition Period - in Years	2 years 5 months 12 days
Restricted stock units
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 41,726
Average Expected Recognition Period - in Years	2 years 7 months 21 days