Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Significant Accounting Policies [Abstract]

Fair Value Measurements for Assets and Liabilities on Recurring Basis

The following table summarizes fair value measurements by level at December 31, 2016 for assets and liabilities measured at fair value on a recurring basis:

(In thousands)	Level I		Level II		Level III			Total
Cash equivalents	$	56,276	$	—	$	—		$	56,276
Warrant liabilities		—		—		(3,789	)		(3,789	)

The following table summarizes fair value measurements by level at December 31, 2015 for assets and liabilities measured at fair value on a recurring basis:

(In thousands)	Level I		Level II		Level III			Total
Cash equivalents	$	20,673	$	—	$	—		$	20,673
Short-term investments		35,035		—		—			35,035
Warrant liabilities		—		—		(693	)		(693	)

Changes in Carrying Amounts of Warrant Liabilities

The changes in carrying amounts of the warrant liability for the years ended December 31, 2016 and 2015 were as follows:

(In thousands)	2016			2015
Beginning balance	$	693		$	5,131
Issued		6,933			—
Exercised		(9	)		—
Net changes in valuation		(3,828	)		(4,438	)
Ending balance	$	3,789		$	693