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, 2020	Aug. 31, 2019
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 180,595	$ 106,188
Less: Allocation of earnings and dividends to participating securities		(1,552)	(623)
Net income available to common shareholders - basic		179,043	105,565
Add: Undistributed earnings reallocated to unvested shareholders		4	2
Net income available to common shareholders - diluted		$ 179,047	$ 105,567
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		128,418	128,882
Average diluted options and awards		365	622
Total shares for diluted earnings per share	[1]	128,783	129,504
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock		$ 1.39	$ 0.82
Method used to calculate basic earnings per share		Two-class	Two-class
Diluted Earnings Per Share of Common Stock		$ 1.39	$ 0.82
Method used to calculate diluted earnings per share		Two-class	Two-class

[1] Restricted shares totaling 225,500 and 178,000 for the three months ended August 31, 2020 and 2019, respectively, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.   In addition, stock appreciation rights (“SARs”) totaling 360,000 and 790,000 for the three months ended August 31, 2020 and 2019, respectively, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.