Consolidated Statement of Changes in Stockholders’ Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Common Stock Class A Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock At Cost	Parent	Noncontrolling Interest
Beginning balance (in shares) at May. 31, 2019		33.4	1.7
Beginning balance at May. 31, 2019	$ 1,272.8	$ 0.4	$ 0.0	$ 620.8	$ (59.7)	$ 1,012.6	$ (302.6)	$ 1,271.5	$ 1.3
Net Income (loss)	(43.7)					(43.8)		(43.8)	0.1
Foreign currency translation adjustment	(2.9)				(2.9)			(2.9)
Pension and post-retirement adjustments (net of tax of $0.4)	4.3				4.3			4.3
Stock-based compensation	3.8			3.8				3.8
Proceeds from issuance of common stock pursuant to stock-based compensation plans	0.7			0.7				0.7
Purchases of treasury stock at cost (in shares)		(1.0)
Purchases of treasury stock at cost	(35.5)						(35.5)	(35.5)
Treasury stock issued pursuant to stock purchase plans (in shares)		0.1
Treasury stock issued pursuant to equity-based plans	1.9			(2.9)			4.8	1.9
Dividends	(20.8)					(20.8)		(20.8)
Ending balance at May. 31, 2020	1,180.6	$ 0.4	$ 0.0	622.4	(58.3)	948.0	(333.3)	1,179.2	1.4
Ending balance (in shares) at May. 31, 2020		32.5	1.7
Pension and postretirement adjustments, tax portion	0.4
Net Income (loss)	(10.9)					(11.0)		(11.0)	0.1
Foreign currency translation adjustment	19.9				19.9			19.9
Pension and post-retirement adjustments (net of tax of $0.4)	3.7				3.7			3.7
Stock-based compensation	6.6			6.6				6.6
Proceeds from issuance of common stock pursuant to stock-based compensation plans	0.4			0.4				0.4
Purchases of treasury stock at cost (in shares)		0.0
Purchases of treasury stock at cost	0.0						0.0	0.0
Treasury stock issued pursuant to stock purchase plans (in shares)		0.2
Treasury stock issued pursuant to equity-based plans	2.6			(2.9)			5.5	2.6
Dividends	(20.6)					(20.6)		(20.6)
Ending balance at May. 31, 2021	1,182.3	$ 0.4	$ 0.0	626.5	(34.7)	916.4	(327.8)	1,180.8	1.5
Ending balance (in shares) at May. 31, 2021		32.7	1.7
Pension and postretirement adjustments, tax portion	2.2
Net Income (loss)	81.0					80.9		80.9	0.1
Foreign currency translation adjustment	(14.5)				(14.5)			(14.5)
Pension and post-retirement adjustments (net of tax of $0.4)	3.8				3.8			3.8
Stock-based compensation	7.8			7.8				7.8
Proceeds from issuance of common stock pursuant to stock-based compensation plans	10.4			10.4				10.4
Purchases of treasury stock at cost (in shares)		(0.9)
Purchases of treasury stock at cost	(33.4)						(33.4)	(33.4)
Treasury stock issued pursuant to stock purchase plans (in shares)		0.7
Treasury stock issued pursuant to equity-based plans	2.0			(17.7)			19.7	2.0
Dividends	(20.8)					(20.8)		(20.8)
Noncontrolling Interest, Period Increase (Decrease)			$ (0.2)
Ending balance at May. 31, 2022	1,218.4	$ 0.4	$ 0.0	$ 627.0	$ (45.4)	$ 976.5	$ (341.5)	$ 1,217.0	$ 1.4
Ending balance (in shares) at May. 31, 2022		32.5	1.7
Pension and postretirement adjustments, tax portion	$ 0.3