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		3 Months Ended
		Aug. 31, 2024	Aug. 31, 2023
Numerator for earnings per share:
Net Income (Loss)		$ 227,692	$ 201,082
Less: Allocation of earnings and dividends to participating securities		(893)	(872)
Net income available to common shareholders - basic		226,799	200,210
Reverse: Allocation of earnings and dividends to participating securities		0	872
Add: Undistributed earnings reallocated to unvested shareholders		4	0
Net income available to common shareholders - diluted		$ 226,803	$ 201,082
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,691	127,633
Average diluted options and awards		729	1,138
Total shares for diluted earnings per share	[1]	128,420	128,771
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 1.78	$ 1.57
Method used to calculate basic earnings per share		Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 1.77	$ 1.56
Method used to calculate diluted earnings per share		Two-class

[1] The dilutive effect of performance-based restricted stock units is included when they have met minimum performance thresholds. The dilutive effect of SARs includes all outstanding awards except awards that are considered antidilutive. SARs are antidilutive when the exercise price exceeds the average market price of the Company’s common shares during the periods presented. For the three months ended August 31, 2024 and 2023, approximately 180,000 and 1,037,000 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.