Investment Securities

At March 31, 2015, securities classified as available-for-sale consisted of the following (in thousands):



	March 31, 2015
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds (1)	$	14,603	$	—	$	—	$	14,603	n/a
Common shares of CO₂ Solutions (2)	563		149		—		712		n/a
Total	$	15,166	$	149	$	—	$	15,315

(1) Money market funds are classified in cash and cash equivalents on our condensed consolidated balance sheets.

(2) Common shares of CO₂ Solutions are classified in marketable securities on our condensed consolidated balance sheets.

There were no marketable securities in an unrealized loss position at March 31, 2015.

At December 31, 2014, securities classified as available-for-sale consisted of the following (in thousands):



	December 31, 2014
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds (1)	$	14,602	$	—	$	—	$	14,602	n/a
Common shares of CO₂ Solutions (2)	563		125		—		688		n/a
Total	$	15,165	$	125	$	—	$	15,290

(1) Money market funds are classified in cash and cash equivalents on our condensed consolidated balance sheets.

(2) Common shares of CO₂ Solutions are classified in marketable securities on our condensed consolidated balance sheets.