Goodwill and Identified Intangible Assets - Summary of Goodwill and Identified Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 85,592	$ 85,857
Accumulated Amortization	(72,775)	(64,578)
Total future amortization expense	$ 12,817	21,279
Developed core technology [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year 2 months 12 days
Gross Carrying Amount	$ 31,707	31,707
Accumulated Amortization	(25,576)	(20,396)
Total future amortization expense	$ 6,131	11,311
Customer relationships/contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 2 months 12 days
Gross Carrying Amount	$ 44,650	44,819
Accumulated Amortization	(38,146)	(35,205)
Total future amortization expense	$ 6,504	9,614
Trademarks and tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year 2 months 12 days
Gross Carrying Amount	$ 623	654
Accumulated Amortization	(441)	(300)
Total future amortization expense	182	354
Maintenance agreements and related relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,500	5,500
Accumulated Amortization	(5,500)	(5,500)
Total future amortization expense	0	0
Order or Production Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,112	3,177
Accumulated Amortization	(3,112)	(3,177)
Total future amortization expense	$ 0	$ 0