Fair Value Measurements

The following tables present the financial instruments that were measured at fair value on a recurring basis at September 30, 2018 and December 31, 2017 by level within the fair value hierarchy (in thousands):



	September 30, 2018
	Level 1		Level 2		Level 3		Total
Money market funds ⁽¹⁾	$	31,058	$	—	$	—	$	31,058
Common shares of CO2 Solutions ⁽²⁾	—		652		—		652
Total	$	31,058	$	652	$	—	$	31,710



	December 31, 2017
	Level 1		Level 2		Level 3		Total
Money market funds ⁽¹⁾	$	6,778	$	—	$	—	$	6,778
Common shares of CO2Solutions ⁽²⁾	—		671		—		671
Total	$	6,778	$	671	$	—	$	7,449

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

⁽²⁾ Common shares of CO2 Solutions are classified as marketable securities, and included in non-current assets on our unaudited condensed consolidated balance sheets.

We determine the fair value of Level 1 assets using quoted prices in active markets for identical assets. We estimated the fair value of our investment in 10,000,000 common shares of CO2 Solutions using the market value of common shares as determined by trading on the TSX Venture Exchange, and we classified our investment in CO2 Solutions as Level 2 assets due to the volatile and low trading volume. There were no transfers between Level 1 and Level 2 securities in the periods presented. (See also Note 6, "Cash Equivalents and Marketable Securities.")

During the three and nine months ended September 30, 2018, unrealized loss of $25 thousand and $20 thousand, respectively, related to our investment in CO2 Solutions were included in other expense, net, in the unaudited condensed consolidated statements of operations. Prior to our adoption of ASU 2016-01, we recorded unrealized gains and losses from our investment in CO2 Solutions in accumulated other comprehensive loss in stockholders' equity. During the three and nine months ended September 30, 2017, unrealized gain related to our investment in CO2 Solutions was $0.1 million and unrealized loss was $21 thousand, respectively, included in other comprehensive gain (loss).