Summary of Significant Accounting Policies - Property and Equipment and Leases (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Property and equipment
Equipment expense	$ 2,500,000	$ 1,100,000	$ 7,300,000	$ 5,500,000
Capitalized software development costs			$ 19,330,000	14,061,000
Capitalized Curriculum Development Costs
Amortization period of capitalized development costs			5 years
Capitalized curriculum development additions			$ 7,461,000	7,524,000
Finance Leases
Purchase option	$ 1		$ 1
Operating Leases
Incremental borrowing rate used as discount rate	3.50%		3.50%
Minimum
Finance Leases
Finance lease term	1 year		1 year
Operating Leases
Operating leases initial term	1 year		1 year
Maximum
Finance Leases
Finance lease term	3 years		3 years
Operating Leases
Operating leases initial term	11 years		11 years
Instructional costs and services
Property and equipment
Depreciation expense	$ 9,800,000	9,300,000	$ 17,900,000	14,800,000
Amortization expense	5,900,000	5,000,000.0	12,100,000	9,700,000
Capitalized Curriculum Development Costs
Amortization expense	3,800,000	4,300,000	8,000,000.0	8,300,000
Selling, general and administrative expenses
Property and equipment
Depreciation expense	1,200,000	1,000,000.0	2,300,000	1,900,000
Amortization expense	1,300,000	1,100,000	2,600,000	2,200,000
Student and state testing computers
Property and equipment
Accelerated depreciation	$ 1,300,000	$ 1,100,000	$ 1,900,000	$ 1,900,000
Student and state testing computers | Minimum
Property and equipment
Useful Life			3 years
Student and state testing computers | Maximum
Property and equipment
Useful Life			5 years
Computer hardware | Minimum
Property and equipment
Useful Life			3 years
Computer hardware | Maximum
Property and equipment
Useful Life			7 years
Computer software | Minimum
Property and equipment
Useful Life			3 years
Computer software | Maximum
Property and equipment
Useful Life			5 years
Web site development
Property and equipment
Useful Life			3 years
Office equipment
Property and equipment
Useful Life			5 years
Furniture and fixtures
Property and equipment
Useful Life			7 years
Capitalized software
Property and equipment
Useful Life			3 years
Buildings | Minimum
Operating Leases
Operating leases initial term	1 year		1 year
Buildings | Maximum
Operating Leases
Operating leases initial term	17 years		17 years