Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 84,149	$ 73,856	$ 184,511	$ 178,695
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	(53,814)	(91,222)	(84,420)	(112,488)
Pension and other postretirement benefit liability adjustments (net of tax of $1,803; $2,573; $3,817; $4,165, respectively)	3,640	4,985	7,800	7,914
Unrealized (loss) gain on securities (net of tax of $632; $(1,276); $(2,595); $(1,155), respectively)	369	(2,567)	(6,715)	(2,491)
Unrealized gain (loss) on derivatives (net of tax of $0; $75; $0; $33, respectively)		283		217
Total other comprehensive (loss)	(49,805)	(88,521)	(83,335)	(106,848)
Total Comprehensive Income (Loss)	34,344	(14,665)	101,176	71,847
Less: Comprehensive Income Attributable to Noncontrolling Interests	716	3,008	1,263	5,388
Comprehensive Income (Loss) Attributable to RPM International Inc. Stockholders	$ 33,628	$ (17,673)	$ 99,913	$ 66,459