Business Segment and Geographic Region Information - Revenue by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue by product lines
Revenue	$ 69,358	$ 65,650	$ 64,451	$ 67,521	$ 70,458	$ 79,317	$ 78,437	$ 73,283	$ 266,980	$ 301,495	$ 203,051
Ion implantation systems services
Revenue by product lines
Revenue									248,885	282,624	183,148
Other systems and services
Revenue by product lines
Revenue									$ 18,095	$ 18,871	$ 19,903