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12. Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
12. Restructuring (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Restructuring charges	$ 385	$ 31	$ 1,214	$ 131
Patent termination
Accrued restructuring costs	0		0		$ 0
Restructuring charges			774
Restructuring cash			(774)
Restructuring noncash			0
Employee termination
Accrued restructuring costs	$ 495		495		$ 265
Restructuring charges			440
Restructuring cash			$ (210)