Accrued Expenses and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued Expenses and Other Current Liabilities
Payroll and related costs	$ 1,429	$ 4,756
Employee benefits	2,731	2,645
Accrued warranty	3,628	4,188	3,399	3,040
Other	2,541	4,516
Accrued expenses and other current liabilities	$ 10,329	$ 16,105