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		6 Months Ended
		Nov. 30, 2022	Nov. 30, 2021	Nov. 30, 2022	Nov. 30, 2021
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 131,344	$ 124,875	$ 300,357	$ 259,457
Less: Allocation of earnings and dividends to participating securities		(676)	(1,103)	(1,466)	(2,198)
Net income available to common shareholders - basic		130,668	123,772	298,891	257,259
Add: Undistributed earnings reallocated to unvested shareholders			2		6
Reverse: Allocation of earnings and dividends to participating securities		676		1,466
Net income available to common shareholders - diluted		$ 131,344	$ 123,774	$ 300,357	$ 257,265
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,585	128,022	127,600	128,058
Average diluted options and awards		1,326	472	1,287	479
Total shares for diluted earnings per share	[1]	128,911	128,494	128,887	128,537
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 1.02	$ 0.97	$ 2.34	$ 2.01
Method used to calculate basic earnings per share		Two-class	Two-class	Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 1.02	$ 0.96	$ 2.33	$ 2.00
Method used to calculate diluted earnings per share		Treasury	Two-class	Treasury	Two-class

[1] For the three months ended November 30, 2022 and 2021, approximately 700,000 and 660,000 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. For the six months ended November 30, 2022 and 2021, approximately 720,000 and 660,000 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.