Discontinued Operations - Assets and Liabilities (Details) - USD ($) $ in Millions	Aug. 31, 2015	May. 31, 2015	Aug. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets of discontinued operations	$ 0.9	$ 3.1	$ 98.5
Noncurrent assets of discontinued operations	0.0	0.0	118.2
Current liabilities of discontinued operations	3.0	14.1	81.2
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	0.4	2.5	82.8
Inventories, net	0.1	0.1	14.2
Prepaid expenses and other current assets	0.4	0.5	1.5
Current assets of discontinued operations	0.9	3.1	98.5
Property, plant and equipment, net	0.0	0.0	1.3
Prepublication costs, net	0.0	0.0	88.5
Royalty advances, net	0.0	0.0	1.1
Goodwill	0.0	0.0	22.7
Other intangibles, net	0.0	0.0	4.2
Other assets and deferred charges	0.0	0.0	0.4
Noncurrent assets of discontinued operations	0.0	0.0	118.2
Accounts payable	0.1	0.1	13.1
Accrued royalties	0.7	0.7	4.6
Deferred revenue	0.1	0.1	51.0
Other accrued expenses	2.1	13.2	12.5
Current liabilities of discontinued operations	$ 3.0	$ 14.1	$ 81.2