Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1
Assets:
Short-term investments	$ 31,957	$ 42,994
Total	31,957	42,994
Fair Value, Inputs, Level 3
Liabilities:
Contingent consideration	2,322	2,695
Total	$ 2,322	$ 2,695