Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 77,322	$ 49,173	$ 183,818	$ 119,359
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	20,967	(12,245)	(7,467)	(52,935)
Pension and other postretirement benefit liability adjustments (net of tax of $1,015; $1,108; $2,119 and $2,090, respectively)	3,404	3,428	7,027	6,483
Unrealized (loss) gain on securities and other (net of tax of $0; $124; $1 and $543, respectively)	(155)	(1,515)	216	962
Unrealized gain on derivatives (net of tax of $305; $234; $274 and $249, respectively)	381	2,349	1,165	3,271
Total other comprehensive income (loss)	24,597	(7,983)	941	(42,219)
Total Comprehensive Income	101,919	41,190	184,759	77,140
Less: Comprehensive Income Attributable to Noncontrolling Interests	343	40	620	204
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 101,576	$ 41,150	$ 184,139	$ 76,936