Acquisition - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 04, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Business acquisition, net revenue generated		$ 70,509	$ 64,829	$ 128,019	$ 122,942
Business acquisition, net loss generated		3,495	$ 5,717	$ 6,113	7,987
Headway
Business Acquisition [Line Items]
Ownership Interest acquired	100.00%
Business acquisition date				Apr. 04, 2017
Aggregate cash consideration	$ 7,500
Cash acquired	4,500
Fair value of contingent consideration	$ 18,300
Contingent consideration agreement, payment period	3 years
Contingent consideration arrangements, minimum	$ 0
Contingent consideration arrangements, maximum	31,500
Contingent consideration, payment	$ 2,000
Contingent payment for key employees remain with the Company, requisite service period	18 months
Accounts receivables assets acquired, fair value	$ 18,900
Gross amount account receivables asset acquired	20,000
Amount due under contract expected to be uncollectible	$ 1,100
Business acquisition, net revenue generated		11,000		$ 11,000
Business acquisition, net loss generated		$ 500		500
Acquisition fees and costs				$ 500	$ 0