Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2019	Aug. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 106,496	$ 70,186
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(28,434)	(40,689)
Pension and other postretirement benefit liability adjustments (net of tax of $1,104 and $982, respectively)	3,623	3,056
Unrealized gain on securities and other (net of tax of $1 and $668, respectively)	371	2,476
Unrealized gain on derivatives (net of tax of $579 and $15, respectively)	784	921
Total other comprehensive (loss)	(23,656)	(34,236)
Total Comprehensive Income	82,840	35,950
Less: Comprehensive Income Attributable to Noncontrolling Interests	277	164
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 82,563	$ 35,786