Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Aug. 31, 2017	Aug. 31, 2016
Income Statement [Abstract]
Net Sales		$ 1,345,394	$ 1,252,063
Cost of Sales		773,386	700,021
Gross Profit		572,008	552,042
Selling, General and Administrative Expenses		394,409	384,085
Interest Expense		26,773	22,778
Investment (Income), Net		(4,453)	(3,838)
Other (Income) Expense, Net		(5)	542
Income Before Income Taxes		155,284	148,475
Provision for Income Taxes		38,381	35,081
Net Income		116,903	113,394
Less: Net Income Attributable to Noncontrolling Interests		487	625
Net Income Attributable to RPM International Inc. Stockholders		$ 116,416	$ 112,769
Average Number of Shares of Common Stock Outstanding:
Basic		131,236	130,600
Diluted	[1]	135,720	135,241
Earnings per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic		$ 0.87	$ 0.85
Diluted		0.86	0.83
Cash Dividends Declared per Share of Common Stock		$ 0.300	$ 0.275

[1] Restricted shares totaling 43,380 for the three months ended August 31, 2017 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 no restricted shares identified as being anti-dilutive for the three months ended August 31, 2016. In addition, stock appreciation rights (“SARs”) totaling 600,000 for the three months ended August 31, 2017 and 1,170,000 for the three months ended August 31, 2016 were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.