Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	Fair Value Measurements at March 31, 2016
	Total		Level 1		Level 2		Level 3
Assets
Money market fund	$	3,975	$	3,975	$	—	$	—
Liabilities
Series A warrant liability	$	558	$	558	$	—	$	—
Series C warrant liability	219		—		—		219
Total liabilities	$	777	$	558	$	—	$	219
	Fair Value Measurements at December 31, 2015
	Total		Level 1		Level 2		Level 3
Assets
Money market fund	$	3,804	$	3,804	$	—	$	—
Liabilities
Series A warrant liability	$	1,213	$	1,213	$	—	$	—
Series B warrant liability	865		—		—		865
Series C warrant liability	462		—		—		462
Total common stock warrant liability	$	2,540	$	1,213	$	—	$	1,327

Summary of Changes in Fair Value of Level1 and Level 3 Financial Instruments

The following table sets forth a summary of the changes in the fair value of the Company’s Level 1 and Level 3 warrants, which are treated as liabilities, as follows (dollars in thousands):

	Series A Warrant				Series B Warrant					Series C Warrant
	Number of Warrants	Liability			Number of Warrants		Liability			Number of Warrants	Liability
Balance at December 31, 2015	2,425,605	$	1,213		116,580		$	865		590,415	$	462
Change in value of Series A Warrants	—	(655		)	—		—			—	—
De-recognition of Series B Warrant liability upon cashless exercise of warrants (485,202 shares issued)	—	—			(102,300	)	(593		)	—	—
De-recognition of Series B Warrant liability upon expiration	—	—			(14,280	)	—			—	—
Change in value of Series B Warrants	—	—			—		(272		)	—	—
Change in value of Series C Warrants	—	—			—		—			—	(243		)
Balance at March 31, 2016	2,425,605	$	558		—		$	—		590,415	$	219