Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurement [Abstract]

Schedule of assets and liabilities measured at fair value on a recurring basis

Assets and liabilities measured at fair value on a recurring basis consist of the following as of December 31, 2017 (in thousands):

			Fair Value Measurements at Reporting Date Using
			Quoted Prices in		Significant
			Active Markets		Other		Significant
			for Identical		Observable		Unobservable
	December 31,		Assets/Liabilities		Inputs		Inputs
	2017		(Level 1)		(Level 2)		(Level 3)
Assets:
Money market funds	$	113	$	113	$	—	$	—
Liabilities:
Deferred payments	$	4,514	$	—	$	—	$	4,514

Assets and liabilities measured at fair value on a recurring basis consist of the following as of December 31, 2016 (in thousands):

			Fair Value Measurements at Reporting Date Using
			Quoted Prices in		Significant
			Active Markets		Other		Significant
			for Identical		Observable		Unobservable
	December 31,		Assets/Liabilities		Inputs		Inputs
	2016		(Level 1)		(Level 2)		(Level 3)
Assets:
Money market funds	$	5,103	$	5,103	$	—	$	—
Liabilities:
Deferred payments	$	11,741	$	—	$	—	$	11,741

Schedule of changes in fair value of level 3 liability

Changes in the fair value of the Company’s Level 3 liabilities during the years ended December 31, 2016 and 2017 are as follows (in thousands):

	2016		2017
Balance as of the beginning of period	$	3,278	$	11,741
Amounts paid		(7,358)		(1,133)
Contingent consideration in connection with NYCDA acquisition		14,500		—
Other adjustments to fair value		1,321		(6,094)
Balance at end of period	$	11,741	$	4,514