Commitments and Contingencies (Details) (USD $)	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Guarantees, Commitments and Contingencies [Line Items]
Standy by letters of credit with certain vendors	$ 1,300,000
Non-cancelable market-based purchase obligation	8,100,000
Estimated future warranty cost	2,063,000	2,153,000	2,017,000	2,172,000	3,358,000	3,935,000
Discontinued Commercial Operation [Member]
Guarantees, Commitments and Contingencies [Line Items]
Maximum contingent liability	200,000
Estimated future warranty cost	$ 400,000			$ 800,000