Marketable Securities, Available for Sale (Tables)

9 Months Ended

Sep. 30, 2013

Investments Debt And Equity Securities [Abstract]

Summary of Available-for-Sale Marketable Securities

The following is a summary of available-for-sale marketable securities (in thousands):

September 30, 2013	Amortized Cost		Unrealized Gain		Unrealized Loss		Market Value
U.S. treasuries	$	4,008	$	4	$	—	$	4,012
Government-sponsored enterprise securities		7,000		—		—		7,000
Corporate bonds		4,856		—		3		4,853
Certificates of deposit		1,171		—		—		1,171
	$	17,035	$	4	$	3	$	17,036

December 31, 2012	Amortized Cost		Unrealized Gain		Unrealized Loss		Market Value
U.S. treasuries	$	10,135	$	1	$	—	$	10,136
Government-sponsored enterprise securities		15,507		—		1		15,506
Corporate bonds		11,509		—		8		11,501
Certificates of deposit		496		—		—		496
	$	37,647	$	1	$	9	$	37,639