Accrued Expenses and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Accrued Expenses and Other Current Liabilities
Payroll and related costs	$ 2,808		$ 4,756
Employee benefits	1,998		2,645
Accrued warranty	3,965	3,506	4,188	3,070	2,270	3,399
Other	4,263		4,516
Accrued expenses and other current liabilities	$ 13,034		$ 16,105