Earnings Per Share - Reconciliation of Numerator and Denominator of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		May 31, 2023	May 31, 2022	May 31, 2021
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 478,691	$ 491,481	$ 502,643
Less: Allocation of earnings and dividends to participating securities		(2,156)	(3,924)	(4,018)
Net income available to common shareholders - basic		476,535	487,557	498,625
Reverse: Allocation of earnings and dividends to participating securities		2,156	3,924
Add: Undistributed earnings reallocated to unvested shareholders				13
Net income available to common shareholders - diluted		$ 478,691	$ 491,481	$ 498,638
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,507	127,948	128,334
Average diluted options and awards		1,309	1,632	593
Total shares for diluted earnings per share	[1]	128,816	129,580	128,927
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 3.74	$ 3.81	$ 3.89
Method used to calculate basic earnings per share		Two-Class	Two-Class	Two-Class
Diluted Earnings Per Share of Common Stock		$ 3.72	$ 3.79	$ 3.87
Method used to calculate diluted earnings per share		Treasury	Treasury	Two-Class

[1] For the years ended May 31, 2023, 2022 and 2021, approximately 750,000, 655,000 and 362,016 shares of stock, respectively, granted under stock-based compensation plans were excluded from the calculation of diluted EPS, as the effect would have been anti-dilutive.