Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 492,466	$ 503,500	$ 305,082
Other Comprehensive Income, Before Tax:
Foreign Currency Translation Adjustments	(98,940)	148,492	(71,839)
Pension and Other Postretirement Benefit Liability Adjustments
Net Gain (Loss) Arising During the Period	29,674	88,958	(109,358)
Prior Service (Credit) Cost Arising During the Period	(294)		893
Less: Amortization of Prior Service (Credit) Included in Net Periodic Pension Cost	(294)	(309)	(246)
Less: Amortization of Net Loss and Settlement Recognition	17,570	33,344	21,176
Effect of Exchange Rates on Amounts Included for Pensions	2,422	(8,009)	1,188
Pension and Other Postretirement Benefit Liability Adjustments	49,078	113,984	(86,347)
Unrealized (Loss) Gain on Available-For-Sale Securities
Unrealized Holding (Losses) Gains During the Period	(1,787)	(593)	1,210
Less: Reclassification Adjustments for Losses (Gains) Included in Net Income	59	(268)
Unrealized (Loss) Gain on Available-For-Sale Securities	(1,728)	(861)	1,210
Unrealized Gain (Loss) on Derivatives	48,572	(31,087)	(6,315)
Other Comprehensive (Loss) Income, Before Tax	(3,018)	230,528	(163,291)
Income Tax (Benefit) Expense Related to Components of Other Comprehensive Income	(19,541)	(27,783)	23,403
Other Comprehensive (Loss) Income, After Tax	(22,559)	202,745	(139,888)
Comprehensive Income	469,907	706,245	165,194
Less: Comprehensive Income Attributable to Noncontrolling Interests	879	988	678
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 469,028	$ 705,257	$ 164,516