Business Combinations - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business combination, contingent consideration paid in full				$ 1,500,000
Glip, Inc.
Business Acquisition [Line Items]
Business combination, consideration payable in combination of cash and common stock		$ 11,900,000
Business combination, fair value of milestone based earn out liability		2,300,000
Business combination, fair value of milestone based earn out liability, current				1,900,000
Business combination contingent consideration maximum potential cash payment		$ 2,000,000
Business combination earn out period of contingent consideration		2 years
Business combination, contingent payment liability				$ 1,400,000
Business combination, contingent payment liability for bonus settlement			$ 0
Glip, Inc. | Class A common stock
Business Acquisition [Line Items]
Business combination, consideration common stock issued			47,591
Business combination, contingent consideration shares issued to settle payout			$ 1,800,000
Glip, Inc. | Asset purchase agreement
Business Acquisition [Line Items]
Business combination, contingent consideration paid in full	$ 1,500,000
Business combination, fair value of milestone based earn out liability		$ 1,500,000