CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY Statement - USD ($) $ in Millions	Total	Common Stock	Common Stock Common Class A	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Parent [Member]	Noncontrolling Interest [Member]
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
Balance (in shares) at Aug. 31, 2019		33,100,000	1,700,000
Net Income (loss)	(58.5)					(58.5)		(58.5)	0.0
Foreign currency translation adjustment	(2.0)				(2.0)			(2.0)
Pension and post-retirement adjustments (net of tax of $0.0)	0.2				0.2			0.2
Stock-based compensation	1.5			1.5				1.5
Purchases of treasury stock at cost (in shares)		(300,000)
Purchases of treasury stock at cost	(12.6)						(12.6)	(12.6)
Treasury stock issued pursuant to equity-based plans (in shares)		0.0
Treasury stock issued pursuant to equity-based plans	0.5			(0.1)			0.6	0.5
Dividends ($0.15 per share)	(5.2)					(5.2)		(5.2)
Ending Balance at Aug. 31, 2019	1,196.7	$ 0.4	$ 0.0	622.2	(61.5)	948.9	(314.6)	1,195.4	1.3
Balance (in shares) at May. 31, 2019		33,400,000	1,700,000
Beginning 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
Balance (in shares) at Aug. 31, 2020		32,500,000	1,700,000
Net Income (loss)	(39.8)					(39.8)		(39.8)	0.0
Foreign currency translation adjustment	10.7				10.7			10.7
Pension and post-retirement adjustments (net of tax of $0.0)	0.1				0.1			0.1
Stock-based compensation	$ 0.6			0.6				0.6
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 equity-based plans (in shares)		0.0
Treasury stock issued pursuant to equity-based plans	0.3			(0.2)			0.5	0.3
Dividends ($0.15 per share)	(5.1)					(5.1)		(5.1)
Ending Balance at Aug. 31, 2020	$ 1,147.4	$ 0.4	$ 0.0	$ 622.8	$ (47.5)	$ 903.1	$ (332.8)	$ 1,146.0	$ 1.4
Balance (in shares) at May. 31, 2020		32,500,000	1,700,000