Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Significant Accounting Policies

Schedule of changes in accumulated balance of the component of other comprehensive (loss)

	Year Ended December 31,
(In thousands)	2016		2015		2014
Accumulated unrealized loss on available-for-sale securities at beginning of period	$	(134)	$	(17)	$	(7)
Change during the period		117		(117)		(10)
Accumulated unrealized loss on available-for-sale securities at end of period	$	(17)	$	(134)	$	(17)

Schedule of weighted average assumptions applied to options

	2016		2015		2014
Average risk free interest rate		1.4%		1.4%		1.4%
Expected dividend yield		—		—		—
Expected lives (years)		4.2		4.2		4.4
Expected volatility		93%		93%		86%
Weighted average grant date fair value of options granted during the period (per share)	$	1.75	$	2.51	$	2.36
Weighted average exercise price of options granted during the period (per share)	$	2.64	$	3.74	$	3.69

Schedule of assets and liabilities measured and recorded in financial statements at fair value on a recurring basis

			Quoted Prices
			in Active
			Markets		Significant
			for Identical		Other		Significant
			Assets or		Observable		Unobservable
			Liabilities		Inputs		Inputs
(In thousands)	Total		(Level 1)		(Level 2)		(Level 3)
December 31, 2016
Assets
Money market funds	$	67,580	$	67,580	$	—	$	—
Short-term investments – corporate bonds		19,729		—		19,729		—
Short-term investments – municipal bonds		8,618		—		8,618		—
Total Assets	$	95,927	$	67,580	$	28,347	$	—
Total Liabilities	$	—	$	—	$	—	$	—
December 31, 2015
Assets
Money market funds	$	26,056	$	26,056	$	—	$	—
Short-term investments – commercial paper		3,974		—		3,974		—
Short-term investments –  corporate bonds		24,575		—		24,575		—
Short-term investments – municipal bonds		5,025		—		5,025		—
Long-term investments – corporate bonds		21,186		—		21,186		—
Long-term investments – municipal bonds		5,811		—		5,811		—
Total Assets	$	86,627	$	26,056	$	60,571	$	—
Total Liabilities	$	—	$	—	$	—	$	—