Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accrued Expenses and Other Current Liabilities
Payroll and related costs	$ 4,838	$ 8,927
Employee benefits	4,888	4,113
Accrued warranty	5,297	7,423
Other	4,033	5,086
Accrued expenses and other current liabilities	$ 19,056	$ 25,549