Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Assets
Money market funds	$ 7,847	$ 5,204
Liabilities
Contingent consideration liability	2,313
Convertible preferred stock warrants	808	525
Derivative liability related to subordinated convertible note	120
Total liabilities	3,241
Fair Value Measured Using - Level 1 [Member]
Assets
Money market funds	7,847	5,204
Liabilities
Contingent consideration liability	0
Convertible preferred stock warrants	0	0
Derivative liability related to subordinated convertible note	0
Total liabilities	0
Fair Value Measured Using - Level 2 [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration liability	0
Convertible preferred stock warrants	0	0
Derivative liability related to subordinated convertible note	0
Total liabilities	0
Fair Value Measured Using - Level 3 [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration liability	2,313
Convertible preferred stock warrants	808	525
Derivative liability related to subordinated convertible note	120
Total liabilities	$ 3,241