Restructuring Activities - Charges and Net Assets (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 23, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Total Revenues		$ 3,778	$ 10,155
Net loss		(2,567)	(1,289)
Total assets		28,921		$ 32,224
Liabilities		5,468		6,049
Payments for restructuring		0	287
Restructuring charge		0	595
CHINA
Restructuring Cost and Reserve [Line Items]
Remaining performance requirements for APC projects		32
Total Revenues		2	338
Net loss		127	$ (850)
Total assets		3,332		4,249
Liabilities		316		399
Total net assets		3,016		$ 3,850
CHINA | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring, expected cost		$ 532
CHINA | Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring charge	$ 63