Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 9,611	$ 6,845	$ (2,168)	$ 24,650
Other comprehensive (loss) income:
Foreign currency translation adjustments	(9,625)	(10,752)	12,919	1,014
Comprehensive (loss) income	(14)	(3,907)	10,751	25,664
Less: net income (loss) attributable to noncontrolling interests	43	9	7	(4)
Foreign currency translation adjustments attributable to noncontrolling interests	6	(5)	4	1
Comprehensive (loss) income attributable to Mistras Group, Inc.	$ (51)	$ (3,921)	$ 10,748	$ 25,669