Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]

Summary of financial instruments measured at fair value on a recurring basis

The following table presents the financial instruments that were measured at fair value on a recurring basis at December 31, 2014 by level within the fair value hierarchy (in thousands):

	December 31, 2014
Financial Assets	Level 1		Level 2		Level 3		Total
Money market funds	$	14,602	$	—	$	—	$	14,602
Common shares of CO2 Solutions			688		—		688
Total	$	14,602	$	688	$	—	$	15,290

The following table presents the financial instruments that were measured at fair value on a recurring basis at December 31, 2013 by level within the fair value hierarchy (in thousands):

	December 31, 2013
Financial Assets	Level 1		Level 2		Level 3		Total
Money market funds	$	16,089	$	—	$	—	$	16,089
Corporate bonds	—		1,005		—		1,005
U.S. Treasury obligations	—		2,000		—		2,000
Common shares of CO2 Solutions	—		795		—		795
Total	$	16,089	$	3,800	$	—	$	19,889

Fair Value Measurements, Nonrecurring

The fair value of assets held for sale at December 31, 2013, measured on a nonrecurring basis, is as follows (in thousands):

	December 31, 2013
Non-Financial Assets	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs
Assets held for sale	$	—	$	—	$	2,179