Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Aug. 31, 2016	Aug. 31, 2015
Income Statement [Abstract]
Net Sales	$ 1,252,063	$ 1,242,526
Cost of Sales	700,021	709,568
Gross Profit	552,042	532,958
Selling, General and Administrative Expenses	384,085	372,854
Interest Expense	22,778	22,460
Investment (Income), Net	(3,838)	(4,068)
Other Expense (Income), Net	542	(489)
Income Before Income Taxes	148,475	142,201
Provision for Income Taxes	35,081	41,839
Net Income	113,394	100,362
Less: Net Income Attributable to Noncontrolling Interests	625	547
Net Income Attributable to RPM International Inc. Stockholders	$ 112,769	$ 99,815
Average Number of Shares of Common Stock Outstanding:
Basic	130,600	130,045
Diluted	135,241	137,307
Earnings per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic	$ 0.85	$ 0.76
Diluted	0.83	0.74
Cash Dividends Declared per Share of Common Stock	$ 0.275	$ 0.260