Goodwill and Acquired Intangible Assets - Schedule of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 425,321	$ 399,191
Accumulated Amortization	(240,442)	(230,843)
Net Carrying Amount	184,879	168,348
Completed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	153,691	145,091
Accumulated Amortization	(86,321)	(81,587)
Net Carrying Amount	67,370	63,504
Customer-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	263,010	245,710
Accumulated Amortization	(149,378)	(144,786)
Net Carrying Amount	113,632	100,924
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	730	700
Accumulated Amortization	(359)	(306)
Net Carrying Amount	371	394
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,400	7,200
Accumulated Amortization	(3,894)	(3,674)
Net Carrying Amount	3,506	3,526
Acquired license rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	490	490
Accumulated Amortization	(490)	(490)
Net Carrying Amount	$ 0	$ 0