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		6 Months Ended
		Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Numerator for earnings per share:
Net income (loss) attributable to RPM International Inc. stockholders		$ 95,463	$ (70,926)	$ 211,879	$ 41,843
Less: Allocation of earnings and dividends to participating securities		(1,313)		(2,828)	(621)
Net income (loss) available to common shareholders - basic		94,150	(70,926)	209,051	41,222
Add: Undistributed earnings reallocated to unvested shareholders		3		7
Add: Income effect of contingently issuable shares		1,379		2,756
Net income (loss) available to common shareholders - diluted		$ 95,532	$ (70,926)	$ 211,814	$ 41,222
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		131,163	130,695	131,204	130,647
Average diluted options		514		544
Additional shares issuable assuming conversion of convertible securities	[1]	3,915		3,915
Total shares for diluted earnings per share	[2]	135,592	130,695	135,663	130,647
Earnings (Loss) Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings (Loss) Per Share of Common Stock		$ 0.72	$ (0.54)	$ 1.59	$ 0.32
Diluted Earnings (Loss) Per Share of Common Stock		$ 0.70	$ (0.54)	$ 1.56	$ 0.32

[1] Represents the number of shares that would be issued if our contingently convertible notes were converted. We include these shares in the calculation of diluted EPS as the conversion of the notes may be settled, at our election, in cash, shares of our common stock, or a combination of cash and shares of our common stock.

[2] Restricted shares totaling 123,262 and 99,612 for the three and six months ended November 30, 2017, respectively, were excluded from the calculation of diluted earnings per share because the grant price of the restricted shares exceeded the average market price of the shares during the period and their effect, accordingly, would have been anti-dilutive. There were 243,000 shares of restricted stock identified as being anti-dilutive for the three months ended November 30, 2016; and none identified as being anti-dilutive for the six months ended November 30, 2016. In addition, stock appreciation rights (“SARs”) totaling 600,000 for the three and six months ended November 30, 2017, and 1,170,000 for the three and six months ended November 30, 2016, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.