Marketable Securities

9 Months Ended

Sep. 30, 2016

Marketable Securities

Marketable Securities

4.  Marketable Securities

Marketable securities available for sale, consisting of debt securities, were as follows (in thousands):

	September 30, 2016
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
U.S. government agencies	$	1,202	$	—	$	—	$	1,202
Commercial paper		7,974		—		—		7,974
Total	$	9,176	$	—	$	—	$	9,176

	December 31, 2015
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
U.S. government agencies	$	—	$	—	$	—	$	—
Commercial paper		—		—		—		—
Total	$	—	$	—	$	—	$	—