Share-Based Compensation - Summary of Share-Based Compensation Expense by Award Type (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 10,627	$ 7,477	$ 19,562	$ 14,214
Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	1,953	2,437	4,143	4,984
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	8,156	4,742	14,440	8,382
Employee Stock Purchase Plan Rights
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 518	$ 298	$ 979	$ 848