Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2016

Accounting Policies [Abstract]

Available-For-Sale Securities

Available-for-sale securities at March 31, 2016 and December 31, 2015 consisted of the following:

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
March 31, 2016:
Corporate debt securities (Due within 1 year)	$	4,748	$	2	$	—		$	4,750
Government agency securities (Due within 1 year)		999		—		—			999
	$	5,747	$	2	$	—		$	5,749
December 31, 2015:
Corporate debt securities (Due within 1 year)	$	6,504	$	—	$	(3	)	$	6,501
Government agency securities (Due within 1 year)		1,000		—		—			1,000
	$	7,504	$	—	$	(3	)	$	7,501

Marketable Securities in Unrealized Loss Position

Marketable securities in an unrealized loss position at December 31, 2015 consisted of the following:

	Aggregate Fair Value		Unrealized Losses
		(in thousands)
Corporate debt securities (Due within 1 year)	$	4,100	$	(3	)
Government agency securities (Due within 1 year)		1,000		—
	$	5,100	$	(3	)

Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis in the accompanying condensed consolidated balance sheets as of March 31, 2016 and December 31, 2015.

	Fair Value Measurements of Cash Equivalents and Marketable Securities as of March 31, 2016
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash equivalents	$	6,907	$	2,143	$	—	$	9,050
Marketable securities		—		5,749		—		5,749
	$	6,907	$	7,892	$	—	$	14,799

	Fair Value Measurements of Cash Equivalents and Marketable Securities as of December 31, 2015
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash equivalents	$	11,462	$	4,812	$	—	$	16,274
Marketable securities		—		7,501		—		7,501
	$	11,462	$	12,313	$	—	$	23,775

Potential Common Shares Excluded from Calculation of Net Loss Per Common Share

The following table sets forth the potential common shares excluded from the calculation of net loss per common share-diluted for the three months ended March 31, 2016 and 2015 because their inclusion would have been anti-dilutive:

	Outstanding at March 31,
	2016		2015
		(in thousands)
Options outstanding		5,584		5,861
Warrants outstanding		609		609
		6,193		6,470

Stock-Based Compensation Expense

During the three months ended March 31, 2016 and 2015, the Company recorded the following stock-based compensation expense:

	Three Months Ended March 31,
	2016		2015
	(in thousands)
Research and development	$	125	$	125
General and administrative		265		233
Restructuring		─		69
	$	390	$	427