Segment Information (Detail) - Schedule of segment reporting information (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Revenues	$ 685.3	$ 667.9	$ 1,003.3	$ 958.3
Bad debt expense	3.3	3.0	4.7	5.9
Depreciation and amortization	15.5	14.5	30.6	28.9
Amortization	12.5	12.4	24.4	24.5
Loss on leases	6.2		6.2
Royalty advances expensed	3.1	4.3	9.3	10.3
Segment operating income (loss)	140.0	129.1	106.8	82.8
Segment assets	1,601.6	1,566.2	1,601.6	1,566.2
Goodwill	155.1	163.7	155.1	163.7
Expenditures for long-lived assets including royalty advances	33.3	61.1	57.3	91.6
Long-lived assets	687.7	700.7	687.7	700.7
Children's Book Publishing and Distribution [Member]
Revenues	388.6	387.3	465.9	460.2
Bad debt expense	1.6	2.3	1.6	4.3
Depreciation and amortization	3.8	3.9	7.5	7.5
Amortization	3.1	3.0	6.2	6.3
Royalty advances expensed	2.7	3.2	7.7	8.3
Segment operating income (loss)	108.6	97.3	58.8	45.7
Segment assets	541.4	540.0	541.4	540.0
Goodwill	54.3	54.3	54.3	54.3
Expenditures for long-lived assets including royalty advances	12.9	7.9	21.1	20.9
Long-lived assets	175.6	182.4	175.6	182.4
Educational Technology and Services [Member]
Revenues	65.4	49.1	162.0	131.2
Bad debt expense	0.4	0.2	0.7	0.5
Depreciation and amortization	0.4	0.5	0.7	0.8
Amortization	5.1	5.5	10.3	11.3
Royalty advances expensed		(0.1)	0.2	0.1
Segment operating income (loss)	14.6	3.4	53.4	33.6
Segment assets	157.6	150.7	157.6	150.7
Goodwill	22.7	27.9	22.7	27.9
Expenditures for long-lived assets including royalty advances	6.0	13.9	11.3	20.0
Long-lived assets	98.6	95.2	98.6	95.2
Classroom And Supplemental Materials Publishing [Member]
Revenues	58.7	52.5	104.4	89.0
Bad debt expense	0.5	(0.2)	0.9	(0.5)
Depreciation and amortization	0.2	0.3	0.5	0.6
Amortization	1.7	1.5	3.1	2.2
Royalty advances expensed	(0.1)	0.3		0.3
Segment operating income (loss)	10.3	7.6	12.4	5.9
Segment assets	158.8	153.8	158.8	153.8
Goodwill	64.0	67.4	64.0	67.4
Expenditures for long-lived assets including royalty advances	3.1	1.7	4.4	2.5
Long-lived assets	81.0	80.4	81.0	80.4
Media, Licensing and Advertising [Member]
Revenues	28.5	33.1	39.2	50.1
Bad debt expense		0.1		0.1
Depreciation and amortization	0.3		0.4	0.5
Amortization	2.1	1.6	3.6	3.3
Royalty advances expensed		0.1	0.1	0.2
Segment operating income (loss)	2.6	5.2	(2.4)	3.0
Segment assets	44.2	48.2	44.2	48.2
Goodwill	5.4	5.4	5.4	5.4
Expenditures for long-lived assets including royalty advances	2.1	2.2	4.0	4.2
Long-lived assets	20.2	19.8	20.2	19.8
Overhead [Member]
Depreciation and amortization	9.4	8.5	18.6	16.9
Loss on leases	6.2		6.2
Segment operating income (loss)	(22.7)	(9.7)	(41.9)	(28.5)
Segment assets	419.5	375.5	419.5	375.5
Expenditures for long-lived assets including royalty advances	7.6	31.4	12.6	36.9
Long-lived assets	242.4	249.9	242.4	249.9
Total Domestic [Member]
Revenues	541.2	522.0	771.5	730.5
Bad debt expense	2.5	2.4	3.2	4.4
Depreciation and amortization	14.1	13.2	27.7	26.3
Amortization	12.0	11.6	23.2	23.1
Loss on leases	6.2		6.2
Royalty advances expensed	2.6	3.5	8.0	8.9
Segment operating income (loss)	113.4	103.8	80.3	59.7
Segment assets	1,321.5	1,268.2	1,321.5	1,268.2
Goodwill	146.4	155.0	146.4	155.0
Expenditures for long-lived assets including royalty advances	31.7	57.1	53.4	84.5
Long-lived assets	617.8	627.7	617.8	627.7
International Segment [Member]
Revenues	144.1	145.9	231.8	227.8
Bad debt expense	0.8	0.6	1.5	1.5
Depreciation and amortization	1.4	1.3	2.9	2.6
Amortization	0.5	0.8	1.2	1.4
Royalty advances expensed	0.5	0.8	1.3	1.4
Segment operating income (loss)	26.6	25.3	26.5	23.1
Segment assets	280.1	298.0	280.1	298.0
Goodwill	8.7	8.7	8.7	8.7
Expenditures for long-lived assets including royalty advances	1.6	4.0	3.9	7.1
Long-lived assets	$ 69.9	$ 73.0	$ 69.9	$ 73.0