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, 2022	May 31, 2021	May 31, 2020
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 491,481	$ 502,643	$ 304,385
Less: Allocation of earnings and dividends to participating securities		(3,924)	(4,018)	(1,956)
Net income available to common shareholders - basic		487,557	498,625	302,429
Reverse: Allocation of earnings and dividends to participating securities		3,924		1,956
Add: Undistributed earnings reallocated to unvested shareholders			13
Net income available to common shareholders - diluted		$ 491,481	$ 498,638	$ 304,385
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,948	128,334	128,468
Average diluted options		1,632	593	1,506
Total shares for diluted earnings per share	[1]	129,580	128,927	129,974
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 3.81	$ 3.89	$ 2.35
Method used to calculate basic earnings per share		Two-Class	Two-Class	Two-Class
Diluted Earnings Per Share of Common Stock		$ 3.79	$ 3.87	$ 2.34
Method used to calculate diluted earnings per share		Treasury	Two-Class	Treasury

[1] For the years ended May 31, 2022, 2021 and 2020, approximately 655,000, 362,016 and 340,000 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.