Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 38,466	$ 12,090	$ 347,136	$ 195,907
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments (net of tax of $273; $0; $3,216 and $0, respectively)	25,718	(14,515)	102,880	(21,980)
Pension and other postretirement benefit liability adjustments (net of tax of $1,356; $1,335; $3,864 and $3,454, respectively)	4,719	4,196	13,623	11,223
Unrealized gain (loss) on securities and other (net of tax of $330; $0; $8 and $1, respectively)	(957)	559	(787)	775
Unrealized (loss) on derivatives (net of tax of $763; $1,275; $6,425 and $1,001, respectively)	(2,554)	(5,565)	(21,043)	(4,402)
Total other comprehensive income (loss)	26,926	(15,325)	94,673	(14,384)
Total Comprehensive Income (Loss)	65,392	(3,235)	441,809	181,523
Less: Comprehensive Income Attributable to Noncontrolling Interests	268	229	752	849
Comprehensive Income (Loss) Attributable to RPM International Inc. Stockholders	$ 65,124	$ (3,464)	$ 441,057	$ 180,674