Marketable Securities

3 Months Ended

Mar. 31, 2017

Marketable Securities

Marketable Securities

4.  Marketable Securities

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

	March 31, 2017
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
U.S. government agencies	$	1,200	$	—	$	—	$	1,200
Commercial paper		800		—		—		800
Total	$	2,000	$	—	$	—	$	2,000

	December 31, 2016
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
U.S. government agencies	$	1,201	$	—	$	—	$	1,201
Commercial paper		6,090		—		—		6,090
Total	$	7,291	$	—	$	—	$	7,291