Summary of Significant Accounting Policies - Disaggregation of revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Summary of Significant Accounting Policies
Number of lines of business \| item									3
Total Revenues	$ 268,931	$ 257,154	$ 257,559	$ 257,121	$ 256,314	$ 253,252	$ 254,872	$ 251,314	$ 1,040,765	$ 1,015,752	$ 917,734
Managed Public School Programs
Summary of Significant Accounting Policies
Total Revenues									920,080	890,275
Institutional
Summary of Significant Accounting Policies
Total Revenues									74,960	89,953
Non-managed Public School Programs
Summary of Significant Accounting Policies
Total Revenues									36,195	50,623
Institutional Software & Services
Summary of Significant Accounting Policies
Total Revenues									38,765	39,330
Private Pay Schools and Other
Summary of Significant Accounting Policies
Total Revenues									$ 45,725	$ 35,524