Annual report pursuant to Section 13 and 15(d)

Balance Sheets and Statements of Operations Details (Cash Equivalents, Marketable Securities and Other Investments) (Details)

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Balance Sheets and Statements of Operations Details (Cash Equivalents, Marketable Securities and Other Investments) (Details) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Schedule of cash equivalents and marketable securities    
Adjusted Cost $ 41,874,000 $ 57,090,000
Gross Unrealized Gains 63,000 45,000
Gross Unrealized Losses 0 (200,000)
Estimated Fair Value 41,937,000 56,935,000
Money market funds
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost 24,789,000 18,866,000
Gross Unrealized Gains 0 0
Gross Unrealized Losses 0 0
Estimated Fair Value 24,789,000 18,866,000
Commercial paper
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost 1,499,000 1,999,000
Gross Unrealized Gains 1,000 0
Gross Unrealized Losses 0 0
Estimated Fair Value 1,500,000 1,999,000
Average Contractual Maturities 70 days 55 days
Corporate bonds
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost 9,512,000 30,908,000
Gross Unrealized Gains 10,000 29,000
Gross Unrealized Losses 0 (45,000)
Estimated Fair Value 9,522,000 30,892,000
Average Contractual Maturities 156 days 270 days
U.S. Treasury obligations
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost 5,511,000 998,000
Gross Unrealized Gains 5,000 4,000
Gross Unrealized Losses 0 0
Estimated Fair Value 5,516,000 1,002,000
Average Contractual Maturities 262 days 274 days
Government-sponsored enterprise securities
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost   3,003,000
Gross Unrealized Gains   12,000
Gross Unrealized Losses   0
Estimated Fair Value 0 3,015,000
Average Contractual Maturities   373 days
Common shares of CO2 Solutions
   
Schedule of cash equivalents and marketable securities    
Adjusted Cost 563,000 1,316,000
Gross Unrealized Gains 47,000 0
Gross Unrealized Losses 0 (155,000)
Estimated Fair Value $ 610,000 $ 1,161,000