Business Combinations - Summary of Fair Value Components of Identifiable Acquired Intangible Assets And Their Estimated Useful Lives (Detail) - Glip, Inc. - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Total identifiable acquired intangible assets subject to amortization, Fair Value	$ 3,850
Customer relationships
Business Acquisition [Line Items]
Total identifiable acquired intangible assets subject to amortization, Fair Value	$ 840
Total identifiable acquired intangible assets subject to amortization, Estimated Useful Life	2 years	2 years	2 years
Developed technology
Business Acquisition [Line Items]
Total identifiable acquired intangible assets subject to amortization, Fair Value	$ 3,010
Total identifiable acquired intangible assets subject to amortization, Estimated Useful Life	5 years	5 years	5 years