Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Income Statement [Abstract]
Net Sales		$ 1,315,416	$ 1,190,770	$ 2,660,810	$ 2,442,833
Cost of Sales		764,401	669,089	1,537,787	1,369,110
Gross Profit		551,015	521,681	1,123,023	1,073,723
Selling, General and Administrative Expenses		419,599	419,494	814,008	803,579
Goodwill and Other Intangible Asset Impairments			188,298		188,298
Interest Expense		26,396	22,905	53,169	45,683
Investment (Income), Net		(3,739)	(2,416)	(8,192)	(6,254)
Other (Income) Expense, Net		(422)	257	(427)	799
Income (Loss) Before Income Taxes		109,181	(106,857)	264,465	41,618
Provision (Benefit) for Income Taxes		13,323	(36,601)	51,704	(1,520)
Net Income (Loss)		95,858	(70,256)	212,761	43,138
Less: Net Income Attributable to Noncontrolling Interests		395	670	882	1,295
Net Income (Loss) Attributable to RPM International Inc. Stockholders		$ 95,463	$ (70,926)	$ 211,879	$ 41,843
Average Number of Shares of Common Stock Outstanding:
Basic		131,163	130,695	131,204	130,647
Diluted	[1]	135,592	130,695	135,663	130,647
Earnings (Loss) per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic		$ 0.72	$ (0.54)	$ 1.59	$ 0.32
Diluted		0.70	(0.54)	1.56	0.32
Cash Dividends Declared per Share of Common Stock		$ 0.320	$ 0.300	$ 0.620	$ 0.575

[1] 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.