Goodwill and Intangible Assets - Schedule of Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Total intangible assets, Gross Carrying Amount	$ 44,352	$ 35,116
Accumulated Amortization	(14,626)	(11,161)
Total	25,922
Total intangible assets, Net Book Value	29,726	23,955
Acquired Intangible Assets, Gross Carrying Amount	37,414	31,330
Acquired Intangible Assets, Accumulated Amortization	(13,896)	(10,801)
Acquired Intangible Assets, Net Book Value	$ 23,518	20,529
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Life	5 years 4 months 24 days
Gross Carrying Amount	$ 35,855	29,771
Accumulated Amortization	(12,761)	(9,741)
Total	$ 23,094	20,030
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Life	6 years 8 months 12 days
Gross Carrying Amount	$ 1,000	1,000
Accumulated Amortization	(577)	(504)
Total	$ 423	496
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Life	6 years 1 month 6 days
Gross Carrying Amount	$ 519	519
Accumulated Amortization	(518)	(516)
Total	$ 1	3
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Life	2 years
Gross Carrying Amount	$ 40	40
Accumulated Amortization	(40)	(40)
Total	0	0
Internal-use Software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,938	3,786
Accumulated Amortization	(730)	(360)
Total	$ 6,208	$ 3,426