Other Non-Current Liabilities - Components of Other Non-Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Other Liabilities Disclosure [Abstract]
Accrued salaries and employee benefits	$ 26,619	$ 34,993
Premise related costs	18,102	18,188
Accrued earnout payments	6,924	8,518
Other	1,559	1,582
Total other non-current liabilities	$ 26,585	$ 28,288