Cash Equivalents and Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2013

Cash Equivalents and Marketable Securities [Abstract]

Schedule of cash equivalents and marketable securities

At September 30, 2013, cash equivalents and marketable securities consisted of the following (in thousands):

	September 30, 2013
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds	$	21,079	$	—	$	—	$	21,079	n/a
Corporate bonds (unamortized cost)	1,004		3		—		1,007		151
U.S. Treasury obligations (unamortized cost)	2,000		2		—		2,002		232
Common shares of CO2 Solutions	563		$	504	$	—	1,067		n/a
Total	$	24,646	$	509	$	—	$	25,155

At December 31, 2012, cash equivalents and marketable securities consisted of the following (in thousands):

	December 31, 2012
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds	$	24,789	$	—	$	—	$	24,789	n/a
Commercial paper	1,499		1		—		1,500		70
Corporate bonds (unamortized cost)	9,512		10		—		9,522		156
U.S. Treasury obligations (unamortized cost)	5,510		5		—		5,515		262
Common shares of CO2 Solutions	563		47		—		610		n/a
Total	$	41,873	$	63	$	—	$	41,936