Segment Information (Details) - Schedule of segment reporting information (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2014		Nov. 30, 2013		Nov. 30, 2014		Nov. 30, 2013		May 31, 2014	May 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 665.6		$ 623.2		$ 949.4		$ 899.5
Bad debt expense	4.2		2.5		6.5		3.9
Depreciation & Amortization, including prepublication and production costs	28.4		30.5		56.4	[1]	59.7	[1]
Asset impairments	2.9		13.4		2.9	[2]	13.4	[2]
Segment operating income (loss)	112.8		94.7		59.4		48.8
Segment assets	1,650.7		1,579.5		1,650.7		1,579.5
Goodwill	144.5		144.5		144.5		144.5		144.5	157.9
Expenditures for long-lived assets including royalty advances	26.8		28.4		56.1		59.1
Long-lived assets	812.8		668.2		812.8		668.2
Children's Book Publishing and Distribution
Segment Reporting Information [Line Items]
Revenues	402.6	[3]	352.1	[3]	457.3		406.7
Bad debt expense	2.2	[3]	1.0	[3]	2.8		1.4
Depreciation & Amortization, including prepublication and production costs	8.2	[2],[3]	7.8	[2],[3]	16.1	[1]	15.8	[1]
Asset impairments	0	[3]	13.4		0	[2]	13.4	[2]
Segment operating income (loss)	108.3	[3]	68.9	[3]	47.8		7.4
Segment assets	494.9		489.6		494.9		489.6
Goodwill	40.9		40.9		40.9		40.9
Expenditures for long-lived assets including royalty advances	9.7	[3]	10.5	[3]	25.5		21.9
Long-lived assets	145.4		149.6		145.4		149.6
Educational Technology and Services
Segment Reporting Information [Line Items]
Revenues	50.9		60.9		140.3		155.7
Bad debt expense	0		0		0.3		0.4
Depreciation & Amortization, including prepublication and production costs	7.8	[2]	7.6	[2]	15.3	[1]	13.9	[1]
Asset impairments	0	[3]	0		0	[2]	0	[2]
Segment operating income (loss)	(1.2)		6.9		29.1		43.1
Segment assets	169.3		180.3		169.3		180.3
Goodwill	22.7		22.7		22.7		22.7
Expenditures for long-lived assets including royalty advances	7.5		7.3		13.5		15.8
Long-lived assets	118.4		118.2		118.4		118.2
Classroom and Supplemental Materials Publishing
Segment Reporting Information [Line Items]
Revenues	64.8		60.9		107.6		98.7
Bad debt expense	0.8		0.6		0.8		0.6
Depreciation & Amortization, including prepublication and production costs	2.9	[2]	2.5	[2]	5.8	[1]	5.1	[1]
Asset impairments	0	[3]	0		0	[2]	0	[2]
Segment operating income (loss)	12.7		11.6		11.8		9.7
Segment assets	154.4		152.8		154.4		152.8
Goodwill	65.4		65.4		65.4		65.4
Expenditures for long-lived assets including royalty advances	1.5		2.6		3.2		4.6
Long-lived assets	88.9		90.3		88.9		90.3
Media, Licensing and Advertising
Segment Reporting Information [Line Items]
Revenues	14.5	[3]	13.7	[3]	25.1		24.1
Bad debt expense	(0.1)	[3]	0.1	[3]	0.1		0.1
Depreciation & Amortization, including prepublication and production costs	1.9	[2],[3]	0.5	[2],[3]	3.5	[1]	1.1	[1]
Asset impairments	0	[3]	0		0	[2]	0	[2]
Segment operating income (loss)	(0.7)	[3]	(1.3)	[3]	(4.2)		(2.9)
Segment assets	28.6		27.1		28.6		27.1
Goodwill	5.4		5.4		5.4		5.4
Expenditures for long-lived assets including royalty advances	1.6	[3]	2.5	[3]	3.4		3.6
Long-lived assets	14.0		14.1		14.0		14.1
Overhead
Segment Reporting Information [Line Items]
Revenues	0	[1],[3]	0	[1],[3]	0	[3]	0	[3]
Bad debt expense	0	[1],[3]	0	[1],[3]	0	[3]	0	[3]
Depreciation & Amortization, including prepublication and production costs	5.5	[1],[2],[3]	10.5	[1],[2],[3]	11.2	[1],[3]	20.5	[1],[3]
Asset impairments	2.9	[1],[3]	0		2.9	[2],[3]	0	[2],[3]
Segment operating income (loss)	(26.2)	[1],[3]	(13.6)	[1],[3]	(43.1)	[3]	(30.0)	[3]
Segment assets	522.9	[3]	456.4	[3]	522.9	[3]	456.4	[3]
Goodwill	0	[3]	0	[3]	0	[3]	0	[3]
Expenditures for long-lived assets including royalty advances	2.9	[1],[3]	2.8	[1],[3]	3.8	[3]	8.0	[3]
Long-lived assets	381.0	[3]	228.7	[3]	381.0	[3]	228.7	[3]
Total Domestic
Segment Reporting Information [Line Items]
Revenues	532.8		487.6		730.3		685.2
Bad debt expense	2.9		1.7		4.0		2.5
Depreciation & Amortization, including prepublication and production costs	26.3		28.9		51.9	[1]	56.4	[1]
Asset impairments	2.9		13.4		2.9	[2]	13.4	[2]
Segment operating income (loss)	92.9		72.5		41.4		27.3
Segment assets	1,370.1		1,306.2		1,370.1		1,306.2
Goodwill	134.4		134.4		134.4		134.4
Expenditures for long-lived assets including royalty advances	23.2		25.7		49.4		53.9
Long-lived assets	747.7		600.9		747.7		600.9
International Segment
Segment Reporting Information [Line Items]
Revenues	132.8		135.6		219.1		214.3
Bad debt expense	1.3		0.8		2.5		1.4
Depreciation & Amortization, including prepublication and production costs	2.1	[2]	1.6	[2]	4.5	[1]	3.3	[1]
Asset impairments	0	[3]	0		0	[2]	0	[2]
Segment operating income (loss)	19.9		22.2		18.0		21.5
Segment assets	280.6		273.3		280.6		273.3
Goodwill	10.1		10.1		10.1		10.1
Expenditures for long-lived assets including royalty advances	3.6		2.7		6.7		5.2
Long-lived assets	$ 65.1		$ 67.3		$ 65.1		$ 67.3

[1] Includes depreciation of property, plant and equipment and amortization of intangible assets, prepublication and production costs.

[2] Includes an asset impairment related to the planned closure of a retail store in New York City in fiscal 2015 and an impairment of goodwill attributable to legacy acquisitions associated with the book club operations in the Children’s Book Publishing and Distribution segment in fiscal 2014.

[3] Overhead includes all domestic corporate amounts not allocated to segments, including expenses and costs related to the management of corporate assets. Unallocated assets are principally comprised of deferred income taxes and property, plant and equipment related to the Company’s headquarters in the metropolitan New York area, its fulfillment and distribution facilities located in Missouri and its facility located in Connecticut.