Reconciliation of Numerator and Denominator of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 33,019	$ 38,242	$ 292,476	$ 346,496
Less: Allocation of earnings and dividends to participating securities		(133)	(185)	(2,222)	(2,740)
Net income available to common shareholders - basic		32,886	38,057	290,254	343,756
Add: Undistributed earnings reallocated to unvested shareholders					9
Reverse: Allocation of earnings and dividends to participating securities		133	185	2,222
Net income available to common shareholders - diluted		$ 33,019	$ 38,242	$ 292,476	$ 343,765
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,943	128,447	128,013	128,455
Average diluted options and awards		1,759	1,502	1,609	597
Total shares for diluted earnings per share	[1]	129,702	129,949	129,622	129,052
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 0.26	$ 0.30	$ 2.27	$ 2.68
Method used to calculate basic earnings per share		Two-class	Two-class	Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 0.25	$ 0.29	$ 2.26	$ 2.66
Method used to calculate diluted earnings per share		Treasury	Treasury	Treasury	Two-class

[1] For the three and nine months ended February 28, 2022, no restricted shares were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive. For the three and nine months ended February 28, 2021, restricted shares totaling 225,500 and 231,450 were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive. In addition, stock appreciation rights (“SARs”) totaling 320,000 and 655,000 for the three and nine months ended February 28, 2022, and 360,000 for both the three and nine months ended February 28, 2021, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.