CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss before noncontrolling interest	$ (10,976)	$ (11,344)	$ (21,790)	$ (15,379)
Other comprehensive income (loss):
Foreign currency translation adjustments	(424)	(2,682)	238	(3,492)
Unrealized foreign exchange gain (loss) on intercompany balance	428	(400)	(251)	(122)
Net unrealized gain (loss) on available-for-sale securities	8	(12)	34	(12)
Other comprehensive income (loss)	12	(3,094)	21	(3,626)
Comprehensive loss	(10,964)	(14,438)	(21,769)	(19,005)
Comprehensive loss attributable to noncontrolling interest	5	8	5	22
Comprehensive loss attributable to CTI	$ (10,959)	$ (14,430)	$ (21,764)	$ (18,983)