Stock-Based Compensation - Schedule of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 164,308	$ 144,506	$ 126,677
Provision for income taxes	(56,237)	(49,014)	(49,033)
Total stock-based compensation, net of taxes	108,071	95,492	77,644
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	20,314	18,287	14,145
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	38,864	29,739	23,927
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	60,246	55,407	53,542
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 44,884	$ 41,073	$ 35,063