Consolidated Statement of Changes in Stockholders' Equity and Comprehensive Income (Loss) (USD $) In Millions, except Share data	Total	Common Class A [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance at May. 31, 2008	$ 873.1	$ 0	$ 0.4	$ 539.1	$ (34.7)	$ 588.3	$ (220.0)
Balance (in Shares) at May. 31, 2008		1,656,200	36,444,518
Comprehensive loss:
Net income (loss)	(14.3)					(14.3)
Other comprehensive loss, net:
Foreign currency translation adjustment	(30.3)				(30.3)
Pension and postretirement adjustments	(12.1)				(12.1)
Total other comprehensive income (loss)	(42.4)
Total comprehensive income (loss)	(56.7)
Stock-based compensation	11.6			11.6
Proceeds from issuance of common stock pursuant to stock-based compensation	2.2			2.2
Proceeds from issuance of common stock pursuant to stock-based compensation (in Shares)			234,446
Purchases of treasury stock at cost	(34.0)						(34.0)
Purchases of treasury stock at cost (in Shares)			(1,938,689)
Dividends	(11.2)					(11.2)
Balance at May. 31, 2009	785.0	0	0.4	552.9	(77.1)	562.8	(254.0)
Balance (in Shares) at May. 31, 2009		1,656,200	34,740,275
Comprehensive loss:
Net income (loss)	56.1					56.1
Other comprehensive loss, net:
Foreign currency translation adjustment	2.8				2.8
Pension and postretirement adjustments	(11.1)				(11.1)
Total other comprehensive income (loss)	(8.3)
Total comprehensive income (loss)	47.8
Stock-based compensation	14.0			14.0
Proceeds from issuance of common stock pursuant to stock-based compensation	3.2			3.2
Proceeds from issuance of common stock pursuant to stock-based compensation (in Shares)			134,045
Purchases of treasury stock at cost	(10.8)						(10.8)
Purchases of treasury stock at cost (in Shares)			(411,977)
Treasury stock issued pursuant to stock purchase plans	2.3			(0.9)			3.2
Treasury stock issued pursuant to stock purchase plans (in Shares)			135,915
Dividends	(11.1)					(11.1)
Balance at May. 31, 2010	830.4	0	0.4	569.2	(85.4)	607.8	(261.6)
Balance (in Shares) at May. 31, 2010		1,656,200	34,598,258
Comprehensive loss:
Net income (loss)	39.4					39.4
Other comprehensive loss, net:
Foreign currency translation adjustment	25.2				25.2
Pension and postretirement adjustments	6.3				6.3
Total other comprehensive income (loss)	31.5
Total comprehensive income (loss)	70.9
Stock-based compensation	13.7			13.7
Proceeds from issuance of common stock pursuant to stock-based compensation	2.9			2.9
Proceeds from issuance of common stock pursuant to stock-based compensation (in Shares)			104,100
Purchases of treasury stock at cost	(166.9)						(166.9)
Purchases of treasury stock at cost (in Shares)			(5,588,125)
Treasury stock issued pursuant to stock purchase plans	0.4			(9.2)			9.6
Treasury stock issued pursuant to stock purchase plans (in Shares)			202,458
Dividends	(11.4)					(11.4)
Balance at May. 31, 2011	$ 740.0	$ 0	$ 0.4	$ 576.6	$ (53.9)	$ 635.8	$ (418.9)
Balance (in Shares) at May. 31, 2011		1,656,200	29,316,691