Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Revenue recognition
Amounts recorded as revenues and school operating expenses	$ 75.1	$ 76.3	$ 212.5	$ 210.9
Reduction in school operating losses included in the entity's revenue	$ 12.5	$ 13.2	$ 40.8	$ 39.7
Minimum
Revenue recognition
Duration of contracts providing access to curriculum via the entity's Web site			1 year
Maximum
Revenue recognition
Duration of contracts providing access to curriculum via the entity's Web site			2 years