Inventories, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014
Inventories, net
Raw materials	$ 78,566	$ 65,723
Work in process	29,219	22,358
Finished goods (completed systems)	8,119	15,982
Inventories, net	115,904	104,063
Inventories, net additional information
Inventory reserves	800	800		$ 300	$ 300	$ 800	$ 200
Charges to cost of sales due to below normal production capacity		1,000	$ 600
Charges to cost of sales due to lower of cost or market value	500	800	700
Inventory reserves
Inventories, net additional information
Decrease in inventory reserves	14,362	2,452	10,913
Decrease in inventory reserves due to obsolescence and excess inventory	10,400
Reduction in reserve due to sales of previously fully reserved inventory	3,800
Provision charge to reserve	1,185	1,003	$ 2,562
Inventory reserves	$ 10,500	$ 23,600