Share-Based Compensation Unrecognized Share-Based Compensation Expense (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 53,848
Stock option
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 9,423
Average Expected Recognition Period - in Years	2 years 4 months 17 days
Restricted stock units
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 44,425
Average Expected Recognition Period - in Years	2 years 6 months 11 days