Marketable Securities

6 Months Ended

Jun. 30, 2017

Marketable Securities

Marketable Securities

4.  Marketable Securities

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

	June 30, 2017
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
Corporate debt securities	$	7,972	$	—	$	—	$	7,972

	December 31, 2016
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
Government and agency securities	$	1,201	$	—	$	—	$	1,201
Corporate debt securities		6,090		—		—		6,090
Total	$	7,291	$	—	$	—	$	7,291