Commitments and Contingencies - Changes in Recorded Amount of Accrued Compensation and Deferred Consideration from Acquisitions (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Business Combination Accrued Compensation And Deferred Consideration Payable [Roll Forward]
Accrued compensation liability, Beginning balance	$ 1,238
Accrued compensation liability, Payments	(1,255)
Accrued compensation liability, Additional accruals	1,339
Accrued compensation liability, Ending balance	1,322
Deferred consideration liability, Beginning balance	2,075
Deferred consideration liability, Payments	(72)
Deferred consideration liability, Additional accruals	28
Deferred consideration liability, Ending balance	2,031
Accrued compensation and Deferred consideration liability, Beginning balance	3,313
Accrued compensation and Deferred consideration liability, Payments	(1,327)
Accrued compensation and Deferred consideration liability, Additional accruals	1,367
Accrued compensation and Deferred consideration liability, Ending balance	$ 3,353