Restructuring Activities - Charges (Details) - USD ($) $ in Thousands		3 Months Ended					6 Months Ended
	Jan. 23, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Total Revenues			$ 8,948		$ 11,847		$ 19,103	$ 24,638
Net loss			(945)	$ (1,289)	(1,753)	$ (216)	(2,234)	(1,969)
Total assets			43,981				43,981		$ 51,719
Liabilities			(11,863)				(11,863)		$ (17,667)
Payments for restructuring			248		94		535	203
Restructuring charge			30		0		625	0
CHINA
Restructuring Cost and Reserve [Line Items]
Total Revenues			(28)		681		310	1,340
Net loss			(540)		(620)		(1,390)	(1,153)
Total assets			5,493		8,546		5,493	8,546
Liabilities			(1,199)		(2,953)		(1,199)	(2,953)
Net Assets			4,294		$ 5,593		4,294	$ 5,593
CHINA | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring, expected cost			562				562
Payments for restructuring			$ 278				535
Restructuring charge							562
CHINA | Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring charge	$ 63						$ 63
Scenario, Forecast | CHINA | Employee Severance
Restructuring Cost and Reserve [Line Items]
Payments for restructuring		$ 90