Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of Fair Value Measurements by Level for Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table summarizes fair value measurements by level at December 31, 2018 for assets and liabilities measured at fair value on a recurring basis:

(In thousands)	Level I		Level II		Level III		Total
Cash equivalents	$	19,731	$	—	$	—	$	19,731
Warrant liabilities		—		—		—		—

The following table summarizes fair value measurements by level at December 31, 2017 for assets and liabilities measured at fair value on a recurring basis:

(In thousands)	Level I		Level II		Level III			Total
Cash equivalents	$	35,834	$	—	$	—		$	35,834
Warrant liabilities		—		—		(527	)		(527	)

Schedule of Changes in Carrying Amounts of Warrant Liabilities

The changes in carrying amounts of the warrant liability for the years ended December 31, 2018 and 2017 were as follows:

(In thousands)	2018			2017
Beginning balance	$	527		$	3,789
Issued		—			—
Exercised					(1,895	)
Net changes in valuation		(527	)		(1,367	)
Ending balance	$	—		$	527