Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

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

The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis (in thousands):

	Fair Value Measurements at December 31, 2017 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	—	$	83,121	$	—	$	83,121
	$	—	$	83,121	$	—	$	83,121
Liabilities:
Derivative liabilities:
Anti-dilution rights	$	—	$	—	$	223	$	223
	$	—	$	—	$	223	$	223

	Fair Value Measurements at December 31, 2016 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Derivative liabilities:
Anti-dilution rights	$	—	$	—	$	1,806	$	1,806
Contingent prepayment option		—		—		902		902
	$	—	$	—	$	2,708	$	2,708

Roll Forward of the Fair values of Derivative Liabilities

The following table provides a roll forward of the aggregate fair values of the Company’s derivative liabilities, for which fair value was determined by Level 3 inputs (in thousands):

	Contingent						Anti-
	Prepayment			Tranche			Dilution
	Options			Rights			Rights			Total
Balance at December 31, 2015	$	—		$	2,404		$	980		$	3,384
Fair value at issuance		908			909			1,780			3,597
Change in fair value		(6	)		(600	)		26			(580	)
Settlement		—			(2,713	)		(980	)		(3,693	)
Balance at December 31, 2016		902			—			1,806			2,708
Change in fair value		42			—			(1,583	)		(1,541	)
Settlement		(944	)		—			—			(944	)
Balance at December 31, 2017	$	—		$	—		$	223		$	223