Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2016	Aug. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 113,394	$ 100,362
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	(11,511)	(30,606)
Pension and other postretirement benefit liability adjustments (net of tax of $2,799 and $2,014, respectively)	5,704	4,160
Unrealized gain (loss) on securities (net of tax of $1,096 and $(3,228), respectively)	1,604	(7,084)
Total other comprehensive (loss)	(4,203)	(33,530)
Total Comprehensive Income	109,191	66,832
Less: Comprehensive Income Attributable to Noncontrolling Interests	625	547
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 108,566	$ 66,285