Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues	$ 742,365	$ 693,227	[1]	$ 1,439,557	$ 1,355,904	[1]
Amount Reclassified [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Software as a service		33,083			63,443
Total net revenues		0			0
Subscription [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues	110,796	74,596		213,954	143,686
Product and License [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues	192,058	190,376		352,755	361,275
Product and License [Member] | Amount Reclassified [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		(20,633)			(41,331)
Support and Services [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues	$ 439,511	428,255		$ 872,848	850,943
Support and Services [Member] | Amount Reclassified [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		19,227			39,160
Technology Service [Member] | Amount Reclassified [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		(31,677)			(61,272)
As Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Software as a service		41,513			80,243
Total net revenues		693,227			1,355,904
As Previously Reported [Member] | Product and License [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		211,009			402,606
As Previously Reported [Member] | Support and Services [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		409,028			811,783
As Previously Reported [Member] | Technology Service [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenues		$ 31,677			$ 61,272

[1] As noted above, prior period amounts have not been adjusted under the modified retrospective method. See Note 2 for further information regarding the Company’s adoption of the revenue recognition standard.