Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Aug. 31, 2018	Aug. 31, 2017
Income Statement [Abstract]
Net Sales		$ 1,459,989	$ 1,345,394
Cost of Sales		865,947	773,386
Gross Profit		594,042	572,008
Selling, General and Administrative Expenses		459,742	394,409
Restructuring Charges		20,076
Interest Expense		24,406	26,773
Investment (Income), Net		(2,433)	(4,453)
Other Expense (Income), Net		313	(5)
Income Before Income Taxes		91,938	155,284
Provision for Income Taxes		21,752	38,381
Net Income		70,186	116,903
Less: Net Income Attributable to Noncontrolling Interests		422	487
Net Income Attributable to RPM International Inc. Stockholders		$ 69,764	$ 116,416
Average Number of Shares of Common Stock Outstanding:
Basic		131,861	131,236
Diluted	[1]	136,430	135,720
Earnings per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic		$ 0.52	$ 0.87
Diluted		0.52	0.86
Cash Dividends Declared per Share of Common Stock		$ 0.320	$ 0.300

[1] Restricted shares totaling 126,750 and 43,380 for the three months ended August 31, 2018 and 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. In addition, stock appreciation rights (SARs) totaling 890,000 and 600,000 for the three months ended August 31, 2018 and 2017, respectively, were excluded from the calculation of diluted earnings per share as their effect would have been anti-dilutive.