Product Warranties (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Product Warranties
Warranty period from the shipment date	18 months
Warranty period from the project startup date	12 months
Change in warranty reserve
Beginning Balance	$ 2,072	$ 1,624
Payments and replacement product	(756)	(801)
Additions to warranty reserve for warranties issued during the period	916	1,249
Change in the warranty reserve for pre-existing warranties	(36)
Ending Balance	$ 2,196	$ 2,072