Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 12,684	$ 19,293	$ 55,822	$ 203,804
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	16,576	(16,214)	(46,919)	(100,634)
Pension and other postretirement benefit liability adjustments (net of tax of $1,863; $1,827; $6,626; $5,645, respectively)	3,222	3,264	12,516	11,064
Unrealized gain (loss) on securities (net of tax of $1,192; $(3,376); $1,968; $(5,971), respectively)	2,577	(7,334)	3,286	(14,049)
Total other comprehensive income (loss)	22,375	(20,284)	(31,117)	(103,619)
Total Comprehensive Income (Loss)	35,059	(991)	24,705	100,185
Less: Comprehensive Income Attributable to Noncontrolling Interests	756	711	2,051	1,974
Comprehensive Income (Loss) Attributable to RPM International Inc. Stockholders	$ 34,303	$ (1,702)	$ 22,654	$ 98,211