Summary of Significant Accounting Policies - Disaggregation of revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Summary of Significant Accounting Policies
Number of lines of revenue | item			2
Total Revenues	$ 376,145	$ 257,559	$ 747,105	$ 514,680
General Education
Summary of Significant Accounting Policies
Percentage of revenues from funding-based contracts	88.00%	88.00%	88.00%	88.00%
Total Revenues	$ 313,989	$ 232,619	$ 627,838	$ 466,185
Career Learning
Summary of Significant Accounting Policies
Total Revenues	$ 62,156	$ 24,940	$ 119,267	$ 48,495
Middle - High School
Summary of Significant Accounting Policies
Percentage of revenues from funding-based contracts	98.00%	98.00%	98.00%	99.00%
Total Revenues	$ 51,376	$ 24,940	$ 100,147	$ 48,495
Adult
Summary of Significant Accounting Policies
Total Revenues	$ 10,780		$ 19,120