Fair Value Measurements - Fair Value Hierarchy of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	$ 69,041	$ 89,220
Acquisition contingent consideration obligations	(8,610)	(8,752)
Fair value assets and liabilities measured on recurring basis, total	60,431	80,468
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	69,041	89,220
Acquisition contingent consideration obligations	0	0
Fair value assets and liabilities measured on recurring basis, total	69,041	89,220
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	0	0
Acquisition contingent consideration obligations	0	0
Fair value assets and liabilities measured on recurring basis, total	0	0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	0	0
Acquisition contingent consideration obligations	(8,610)	(8,752)
Fair value assets and liabilities measured on recurring basis, total	$ (8,610)	$ (8,752)