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, 2021	Aug. 31, 2020
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders		$ 134,582	$ 180,595
Less: Allocation of earnings and dividends to participating securities		(1,142)	(1,552)
Net income available to common shareholders - basic		133,440	179,043
Add: Undistributed earnings reallocated to unvested shareholders		4	4
Net income available to common shareholders - diluted		$ 133,444	$ 179,047
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		128,083	128,418
Average diluted options and awards		487	365
Total shares for diluted earnings per share	[1]	128,570	128,783
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Earnings Per Share Basic		$ 1.04	$ 1.39
Method used to calculate basic earnings per share		Two-class	Two-class
Earnings Per Share Diluted		$ 1.04	$ 1.39
Method used to calculate diluted earnings per share		Two-class	Two-class

[1] Restricted shares totaling 157,700 and 225,500 for the three months ended August 31, 2021 and 2020, 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 680,000 and 360,000 for the three months ended August 31, 2021 and 2020, respectively, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.