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, 2023	Aug. 31, 2022
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 201,082	$ 169,013
Less: Allocation of earnings and dividends to participating securities		(872)	(1,312)
Net income available to common shareholders - basic		200,210	167,701
Reverse: Allocation of earnings and dividends to participating securities		872
Add: Undistributed earnings reallocated to unvested shareholders			4
Net income available to common shareholders - diluted		$ 201,082	$ 167,705
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,633	127,617
Average diluted options and awards		1,138	544
Total shares for diluted earnings per share	[1]	128,771	128,161
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 1.57	$ 1.31
Method used to calculate basic earnings per share		Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 1.56	$ 1.31
Method used to calculate diluted earnings per share		Treasury	Two-class

[1] For the three months ended August 31, 2023 and 2022, approximately 1,037,000 and 715,000 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.