Components of Total Equity and Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Stockholders Equity Note [Line Items]
Total equity, beginning of period	$ 1,292,224	$ 1,591,478	$ 1,293,465	$ 1,578,594
Net income	19,293	(78,952)	203,804	99,743
Other Comprehensive Income:
Foreign currency translation adjustments	(16,214)	(79,275)	(100,634)	(191,763)
Pension and other postretirement benefit liability adjustments, net of tax	3,264	6,511	11,064	14,425
Unrealized (loss) gain on securities, net of tax	(7,334)	(3,488)	(14,049)	(5,979)
Unrealized gain on derivatives, net of tax		420		637
Total other comprehensive (loss)	(20,284)	(75,832)	(103,619)	(182,680)
Total Comprehensive Income (Loss)	(991)	(154,784)	100,185	(82,937)
Dividends paid	(36,530)	(34,778)	(107,806)	(101,541)
Other noncontrolling interest activity	(186)		(1,559)
Increase in equity ownership of SPHC		(147,901)		(147,901)
Shares repurchased and returned for taxes	(21,473)	(25,800)	(66,765)	(27,588)
Stock option exercises, net of shares returned for taxes		(984)		(479)
Stock based compensation expense	7,476	941	23,000	2,845
Restricted awards, net		5,621		12,800
Total Equity, end of period	1,240,520	1,233,793	1,240,520	1,233,793
Total RPM International Inc. Equity
Stockholders Equity Note [Line Items]
Total equity, beginning of period	1,290,261	1,390,387	1,291,392	1,382,844
Net income	18,582	(57,348)	201,830	111,497
Other Comprehensive Income:
Foreign currency translation adjustments	(16,214)	(79,063)	(100,634)	(186,263)
Pension and other postretirement benefit liability adjustments, net of tax	3,264	6,346	11,064	13,480
Unrealized (loss) gain on securities, net of tax	(7,334)	(3,488)	(14,049)	(5,979)
Unrealized gain on derivatives, net of tax		497		668
Total other comprehensive (loss)	(20,284)	(75,708)	(103,619)	(178,094)
Total Comprehensive Income (Loss)	(1,702)	(133,056)	98,211	(66,597)
Dividends paid	(36,530)	(34,778)	(107,806)	(101,541)
Other noncontrolling interest activity		(47)
Increase in equity ownership of SPHC		29,366		29,366
Shares repurchased and returned for taxes	(21,473)	(25,800)	(66,765)	(27,588)
Stock option exercises, net of shares returned for taxes		(984)		(479)
Stock based compensation expense	7,476	941	23,000	2,845
Restricted awards, net		5,621		12,800
Total Equity, end of period	1,238,032	1,231,650	1,238,032	1,231,650
Noncontrolling Interest
Stockholders Equity Note [Line Items]
Total equity, beginning of period	1,963	201,091	2,073	195,750
Net income	711	(21,604)	1,974	(11,754)
Other Comprehensive Income:
Foreign currency translation adjustments		(212)		(5,500)
Pension and other postretirement benefit liability adjustments, net of tax		165		945
Unrealized gain on derivatives, net of tax		(77)		(31)
Total other comprehensive (loss)		(124)		(4,586)
Total Comprehensive Income (Loss)	711	(21,728)	1,974	(16,340)
Other noncontrolling interest activity	(186)	47	(1,559)
Increase in equity ownership of SPHC		(177,267)		(177,267)
Total Equity, end of period	$ 2,488	$ 2,143	$ 2,488	$ 2,143