Business Segment and Geographic Region Information - Revenue by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue by product lines
Revenue	$ 107,723	$ 69,453	$ 74,305	$ 91,477	$ 105,683	$ 95,374	$ 119,333	$ 122,185	$ 342,958	$ 442,575	$ 410,561
Ion implantation systems and services
Revenue by product lines
Revenue									326,029	421,747	391,051
Other systems and services
Revenue by product lines
Revenue									$ 16,929	$ 20,828	$ 19,510