Related Party Transactions (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Related Party Transactions      
Revenue from product sales $ 4,809,000 $ 4,394,000 $ 6,030,000
Accounts receivable 1,500,000 600,000  
Investors | Company 1      
Related Party Transactions      
Revenue from product sales 4,108,000 2,889,000 2,142,000
Investors | Company 2      
Related Party Transactions      
Revenue from product sales 682,000 950,000 1,290,000
Investors | Company 3      
Related Party Transactions      
Revenue from product sales 19,000 426,000 791,000
Investors | Company 4      
Related Party Transactions      
Revenue from product sales   $ 129,000 $ 1,807,000