Summary of Gross Carrying Amount and Accumulated Amortization for Intangible Assets Resulting from Acquisitions (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 21,539	$ 15,239
Accumulated amortization	(11,322)	(10,874)
Intangible Assets, net	$ 10,217	4,365
Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	3 years
Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	12 years
Trademarks
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	5 years
Gross carrying amount	$ 400
Accumulated amortization	(10)
Intangible Assets, net	390
Developed Technology
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying amount	7,600	4,600
Accumulated amortization	(3,406)	(3,257)
Intangible Assets, net	$ 4,194	1,343
Developed Technology | Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	10 years
Developed Technology | Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	12 years
Customer Relationship
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 13,539	10,639
Accumulated amortization	(7,906)	(7,617)
Intangible Assets, net	$ 5,633	$ 3,022
Customer Relationship | Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	4 years
Customer Relationship | Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization period (in years)	12 years