Share-Based Payments - Stock Option and Restricted Stock Unit Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 12,671	$ 12,364
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	3,073	2,379
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 9,598	$ 9,985