Summary of Significant Accounting Policies - Impact on Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Accounts receivable, net	$ 574,810	$ 437,051	[1]
Current portion of deferred commissions	139,890	109,643	[1]
Prepaid expenses and other current assets	132,071	95,959	[1]
Deferred commissions, less current portion	282,490	224,252	[1]
Other assets	73,458	51,832	[1]
Liabilities
Accrued expenses and other current liabilities	330,246	253,257	[1]
Current portion of deferred revenue	1,651,594	1,210,695	[1]
Deferred revenue, less current portion	38,597	36,120	[1]
Other long-term liabilities	55,064	65,884	[1]
Stockholder’s equity
Accumulated other comprehensive (loss) income	(4,035)	5,767	[1]
Accumulated deficit	$ (978,780)	(958,564)	[1]
Previously Reported
Assets
Accounts receivable, net		434,895
Current portion of deferred commissions		118,690
Prepaid expenses and other current assets		77,681
Deferred commissions, less current portion		85,530
Other assets		49,600
Liabilities
Accrued expenses and other current liabilities		244,605
Current portion of deferred revenue		1,280,499
Deferred revenue, less current portion		39,884
Other long-term liabilities		43,239
Stockholder’s equity
Accumulated other comprehensive (loss) income		(889)
Accumulated deficit		$ (1,146,520)

[1] As adjusted to reflect the impact of the full retrospective adoption of Topic 606.