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, 2022	Aug. 31, 2021
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 169,013	$ 134,582
Less: Allocation of earnings and dividends to participating securities		(1,312)	(1,142)
Net income available to common shareholders - basic		167,701	133,440
Add: Undistributed earnings reallocated to unvested shareholders		4	4
Net income available to common shareholders - diluted		$ 167,705	$ 133,444
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		127,617	128,083
Average diluted options and awards		544	487
Total shares for diluted earnings per share	[1]	128,161	128,570
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 1.31	$ 1.04
Method used to calculate basic earnings per share		Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 1.31	$ 1.04
Method used to calculate diluted earnings per share		Two-class	Two-class

[1] For the three months ended August 31, 2022 and 2021, approximately 715,000 and 837,700 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.