Acquisition of Txcell S.A. - Summary of Non-controlling Interest (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Noncontrolling Interest [Abstract]
Non-controlling interest at acquisition	$ 35,829	$ 35,829
Shares acquired post acquisition		(34,516)
Non-controlling interest of acquired entity		1,313
Foreign currency effect		(19)
Net loss attributable to non-controlling interest	(555)	(555)
Non-controlling interest at December 31, 2018	$ 739	$ 739