Fair Value Measurements - Fair Value Hierarchy of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair value, inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition contingent consideration obligations	$ (1,200)
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	65,136	$ 77,935
Acquisition contingent consideration obligations	(1,968)	(3,320)
Fair value assets and liabilities measured on recurring basis, total	63,168	74,615
Fair value, measurements, recurring | Fair value, inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents (money market accounts)	65,136	77,935
Acquisition contingent consideration obligations	0	0
Fair value assets and liabilities measured on recurring basis, total	65,136	77,935
Fair value, measurements, recurring | Fair value, inputs, 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
Fair value, measurements, recurring | Fair value, inputs, 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	(1,968)	(3,320)
Fair value assets and liabilities measured on recurring basis, total	$ (1,968)	$ (3,320)