Deferred Revenue - Schedule of Deferred Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Total deferred revenue, current	$ 528,752		$ 546,615	[1]
Total deferred revenue, non-current	358,403		363,485	[1]
Total deferred revenue	887,155	$ 879,556	910,100
Product, subscription and support
Revenue from External Customer [Line Items]
Total deferred revenue, current	476,603		496,218
Total deferred revenue, non-current	358,350		363,313
Professional services
Revenue from External Customer [Line Items]
Total deferred revenue, current	52,149		50,397
Total deferred revenue, non-current	$ 53		$ 172

[1] Certain prior period amounts have been adjusted as a result of adoption of the new revenue recognition standard.