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		9 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Numerator for earnings per share:
Net income (loss) attributable to RPM International Inc. stockholders		$ 18,582	$ (57,348)	$ 201,830	$ 111,497
Less: Allocation of earnings and dividends to participating securities		(316)		(3,375)	(2,347)
Net income (loss) available to common shareholders - basic		18,266	(57,348)	198,455	109,150
Add: Undistributed earnings reallocated to unvested shareholders					2
Reverse: Allocation of earnings and dividends to participating securities				3,375
Add: Income effect of contingently issuable shares				4,067	4,026
Net income (loss) available to common shareholders - diluted		$ 18,266	$ (57,348)	$ 205,897	$ 113,178
Denominator for basic and diluted earnings per share:
Basic weighted average common shares		129,068	129,795	129,506	130,039
Average diluted options				3,456	1,080
Additional shares issuable assuming conversion of convertible securities				3,886	3,876
Total shares for diluted earnings per share	[1],[2]	129,068	129,795	136,848	134,995
Earnings (Loss) per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings (Loss) Per Share of Common Stock		$ 0.14	$ (0.44)	$ 1.53	$ 0.84
Diluted Earnings (Loss) Per Share of Common Stock		$ 0.14	$ (0.44)	$ 1.50	$ 0.84

[1] For the nine month period ended February 28, 2015, approximately 3.0 million shares of stock granted under stock-based compensation plans were excluded from the calculation of diluted EPS, as the effect would have been anti-dilutive.

[2] For the three months ended February 28, 2015, basic weighted-average shares outstanding and basic net income available to common shareholders under the treasury method are used in calculating basic and diluted earnings per share as a result of the reported loss for the period. For the three month period ended February 29, 2016, basic weighted-average shares outstanding and basic net income available to common shareholders are used in calculating diluted earnings per share under the two-class method, as that method resulted in the most dilutive earnings per share. For the nine month period ended February 29, 2016, basic and diluted earnings per share are calculated under the two-class method and the treasury method, respectively, as those methods resulted in the most dilutive earnings per share.