Summary of Quarterly Operating Results and Comprehensive Income (Unaudited) (Quarterly Impact of Certain Items) (Details 2) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Quarterly Impact of Certain Items [Line Items]
Settlement gain, after tax	$ 10.8								$ 10.8
Settlement gain, per share (dollars per share)	$ 1.92
Net non-operating gain (loss) from the sales of land and marketable equity securities, after tax	$ (5.0)		$ 23.9	$ 1.1					20.0
Net non-operating gain (loss) from the sales of land and marketable equity securities, per share (dollars per share)	$ (0.90)		$ 4.23	$ 0.19
Net non-operating gain (loss) on the sale of businesses and an investment and on the formation of a JV, after tax			$ 1.7	$ 11.9		$ (24.3)	$ 5.0	$ 3.6	13.6	$ (15.7)
Net non-operating gain (loss) on the sale of businesses and an investment and on the formation of a JV, per share (dollars per share)			$ 0.29	$ 2.08		$ (4.16)	$ 0.85	$ 0.50
Non-operating expense from the write-down of cost and equity method investments, after tax	$ 14.5	$ 9.6							24.1
Non-operating expense from the write-down of cost and equity method investments, per share (dollars per share)	$ (2.57)	$ (1.70)
Non-operating unrealized foreign currency gains (losses), after tax	$ (4.2)	$ (2.4)	$ (15.4)	$ (3.4)	$ 0.4	$ (8.0)	$ 2.3	$ (4.4)	(25.5)	(9.7)
Non-operating unrealized foreign currency gains (losses), per share (dollars per share)	$ (0.75)	$ (0.43)	$ (2.73)	$ (0.60)	$ 0.07	$ (1.37)	$ 0.39	$ (0.75)
Modification of stock option awards and restricted stock awards, after tax					$ 3.7	$ 11.6				15.3
Modification of stock option awards and restricted stock awards, per share (dollars per share)					$ (0.63)	$ (1.99)
Gain on sale of land, after tax					$ 13.2					13.2
Gain on sale of land, per share (dollars per share)					$ 2.27
Kaplan and other businesses [Member]
Quarterly Impact of Certain Items [Line Items]
Goodwill and other long-lived assets impairment, after tax					$ 3.7	$ 217.1	$ 4.4			225.2
Goodwill and other long-lived assets impairment, per share (dollars per share)					$ (0.63)	$ (37.85)	$ (0.75)
Education division, corporate office and other businesses [Member]
Quarterly Impact of Certain Items [Line Items]
Restructuring and related charges, after tax					$ 5.5	$ 5.8	$ 10.7	$ 6.8		$ 28.9
Restructuring and related charges, per share (dollars per share)					$ (0.96)	$ (1.00)	$ (1.82)	$ (1.17)
Education [Member]
Quarterly Impact of Certain Items [Line Items]
Restructuring and related charges, after tax	$ 4.5	$ 1.1	$ 0.9	$ 1.2					7.7
Restructuring and related charges, per share (dollars per share)	$ (0.81)	$ (0.19)	$ (0.15)	$ (0.21)
Education [Member] | Kaplan International [Member]
Quarterly Impact of Certain Items [Line Items]
Net nonrecurring deferred tax benefit adjustment		$ 8.3							8.3
Net nonrecurring deferred tax benefit adjustment, per share (dollars per share)		$ 1.47
Education [Member] | Higher Education [Member]
Quarterly Impact of Certain Items [Line Items]
Net nonrecurring deferred tax benefit adjustment			$ 5.6						$ 5.6
Net nonrecurring deferred tax benefit adjustment, per share (dollars per share)			$ 1.00