Cash Equivalents, Marketable Securities and Other Investments (Tables)

12 Months Ended

Dec. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Available-for-sale Securities

At December 31, 2013, cash equivalents, marketable securities and other investments consisted of the following (in thousands):

	December 31, 2013
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds	$	16,089	$	—	$	—	$	16,089	n/a
Corporate bonds	1,002		3		—		1,005		140
U.S. Treasury obligations	2,000		—		—		2,000		59
Common shares of CO2 Solutions	563		232		—		795		n/a
Total	$	19,654	$	235	$	—	$	19,889

At December 31, 2012, cash equivalents, marketable securities and other investments 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	9,512		10		—		9,522		156
U.S. Treasury obligations	5,511		5		—		5,516		262
Common shares of CO2 Solutions	563		47		—		610		n/a
Total	$	41,874	$	63	$	—	$	41,937