Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 12,090	$ 14,496	$ 195,907	$ 133,855
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(14,515)	20,823	(21,980)	(32,111)
Pension and other postretirement benefit liability adjustments (net of tax of $1,335; $711; $3,454 and $2,801, respectively)	4,196	2,479	11,223	8,962
Unrealized gain on securities and other (net of tax of $0; $0; $1 and $543, respectively)	559	221	775	1,183
Unrealized gain (loss) on derivatives (net of tax of $1,275; $97; $1,001 and $346, respectively)	(5,565)	(604)	(4,402)	2,667
Total other comprehensive income (loss)	(15,325)	22,919	(14,384)	(19,299)
Total Comprehensive Income (Loss)	(3,235)	37,415	181,523	114,556
Less: Comprehensive Income (Loss) Attributable to Noncontrolling Interests	229	(219)	849	(14)
Comprehensive Income (Loss) Attributable to RPM International Inc. Stockholders	$ (3,464)	$ 37,634	$ 180,674	$ 114,570