Discontinued Operations - Revenues (Details) - Discontinued Operations - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015		Feb. 29, 2016	Feb. 28, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 0.4	$ 35.5		$ 0.7	$ 183.3
Operating costs and expenses	0.6	46.1	[1]	2.2	158.8	[1]
Interest income (expense)	0.0	0.1		0.1	0.1
Gain (loss) on sale	(2.9)			(2.9)
Earnings (loss) before income taxes	(3.1)	(10.5)		(4.3)	24.6
Provision (benefit) for income taxes	(1.3)	(4.1)		(1.7)	10.3
Earnings (loss) from discontinued operations, net of tax	(1.8)	(6.4)		(2.6)	14.3
Ed Tech
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0.0	33.6		0.0	174.1
Operating costs and expenses	0.3	43.4	[1]	1.2	148.0	[1]
Interest income (expense)	0.0	0.0		0.0	0.0
Gain (loss) on sale	(2.9)			(2.9)
Earnings (loss) before income taxes	(3.2)	(9.8)		(4.1)	26.1
Provision (benefit) for income taxes	(1.3)	(3.8)		(1.6)	10.9
Earnings (loss) from discontinued operations, net of tax	(1.9)	(6.0)		(2.5)	15.2
Unabsorbed overhead		3.8		11.2
Ed Tech | Cost of goods sold
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Unabsorbed overhead		0.1			0.2
Ed Tech | Selling general and administrative expenses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Unabsorbed overhead		3.7			11.0
All Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0.4	1.9		0.7	9.2
Operating costs and expenses	0.3	2.7	[1]	1.0	10.8	[1]
Interest income (expense)	0.0	0.1		0.1	0.1
Gain (loss) on sale	0.0			0.0
Earnings (loss) before income taxes	0.1	(0.7)		(0.2)	(1.5)
Provision (benefit) for income taxes	0.0	(0.3)		(0.1)	(0.6)
Earnings (loss) from discontinued operations, net of tax	$ 0.1	$ (0.4)		$ (0.1)	$ (0.9)

[1] For the three and nine months ended February 28, 2015, Operating costs and expenses of the continuing operations included costs related to unabsorbed overhead burden associated with the Ed Tech business of $3.8 and $11.2, respectively. These costs were included in the Overhead segment. For the three and nine months ended February 28, 2015, $0.1 and $0.2, respectively, of the costs were recorded in Cost of goods sold and $3.7 and $11.0, respectively, were recorded in Selling, general and administrative expenses