Discontinued Operations - Revenues (Details) - Discontinued Operations - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 0.1	$ 93.3
Operating costs and expenses	1.0	59.9
Earnings (loss) before income taxes	(0.9)	33.4
Provision (benefit) for income taxes	(0.4)	13.6
Earnings (loss) from discontinued operations, net of tax	(0.5)	19.8
Ed Tech
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0.0	90.2
Operating costs and expenses	0.6	55.9	[1]
Earnings (loss) before income taxes	(0.6)	34.3
Provision (benefit) for income taxes	(0.3)	13.9
Earnings (loss) from discontinued operations, net of tax	(0.3)	20.4
Unabsorbed overhead		3.9
All Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0.1	3.1
Operating costs and expenses	0.4	4.0
Earnings (loss) before income taxes	(0.3)	(0.9)
Provision (benefit) for income taxes	(0.1)	(0.3)
Earnings (loss) from discontinued operations, net of tax	$ (0.2)	$ (0.6)

[1] Operating costs and expenses included costs related to unabsorbed overhead burden associated with the Ed Tech business of $3.9.