Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes the Company's financial assets and liabilities measured at fair value on a recurring basis at December 31, 2017 and 2016 by level within the fair value hierarchy. Financial assets and financial liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement:

	At December 31, 2017
	Quoted		Significant
	Prices in		Other		Significant
	Active		Observable		Unobservable
	Markets		Inputs		Inputs		Total Fair
	(Level 1)		(Level 2)		(Level 3)		Value
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	35,521		—		—	$	35,521
U.S. treasury securities		—		11,974				11,974
U.S. government and agency securities		—		50,352		—		50,352
Short-term investments:
U.S. treasury securities		—		12,972		—		12,972
U.S. government and agency securities		—		29,936		—		29,936
Total financial assets	$	35,521	$	105,234	$	—	$	140,755
Liabilities:
Contingent consideration		—		—	$	682	$	682
Total financial liabilities	$	—	$	—	$	682	$	682
	As of  December 31, 2016
	Quoted		Significant
	Prices in		Other		Significant
	Active		Observable		Unobservable
	Markets		Inputs		Inputs		Total Fair
	(Level 1)		(Level 2)		(Level 3)		Value
	(in thousands)
Assets:
Cash equivalents
Money market funds	$	57,032		—		—	$	57,032
Total financial assets	$	57,032	$	—	$	—	$	57,032
Liabilities:
Contingent consideration		—		—	$	388	$	388
Total financial liabilities	$	—	$	—	$	388	$	388

Summary of Changes in Level 3 Financial Instruments

The following table summarizes the changes in Level 3 financial instruments (in thousands).

	Amount
Fair value at December 31, 2015	$	—
Contingent consideration from Crisis Commander acquisition		388
Fair value at December 31, 2016	$	388
Foreign currency translation		44
Contingent consideration from IDV acquisition		5,020
Change in fair value of contingent consideration obligation from IDV acquisition		(1,020	)
Payments made during the year from IDV acquisition		(3,750	)
Fair value at December 31, 2017	$	682