Cash Equivalents and Marketable Securities (Additional Information) (Details) - USD ($)	1 Months Ended
	Dec. 31, 2009	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents		$ 19,240,000	$ 23,273,000	$ 26,487,000	$ 22,130,000
Money market funds		11,200,000	11,100,000
Cash		8,100,000	12,153,000
Initial ownership percentage at the time of investment	16.60%
Statutory resale restriction expiry period	4 months
Number of marketable securities in unrealized loss position		$ 0	$ 0
Common shares of CO2 Solutions
Schedule of Available-for-sale Securities [Line Items]
Number of CO2 Solutions common shares we invested in (shares)	10,000,000