Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (98,522)	$ (5,286)
Other comprehensive income (loss):
Foreign currency translation adjustments	(17,009)	2,131
Comprehensive loss	(115,531)	(3,155)
Less: comprehensive income (loss) attributable to non-controlling interest	(19)	9
Comprehensive loss attributable to Mistras Group, Inc.	$ (115,512)	$ (3,164)