Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Summary of valuation of the Company's investments and financial instruments that are measured at fair value on a recurring basis

The following table summarizes the valuation of the Company’s financial instruments that are measured at fair value on a recurring basis:

	March 31, 2018								December 31, 2017
			Fair value measurement category								Fair value measurement category
(In thousands)	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Liabilities:
Warrant liabilities	$	1,921	$	—	$	1,921	$	—	$	1,014	$	—	$	1,014	$	—

Summary of change in estimated fair value of warrant liabilities

The following table summarizes the change in the estimated fair value of the Company’s outstanding warrant liabilities as of March 31, 2018: 

Warrant Liabilities (In thousands)
Balance at December 31, 2017	$	1,014
Increase in fair value	2,907
Warrant exercise	(2,000		)
Balance at March 31, 2018	$	1,921