Finance and Operating Leases - Lease cost and other information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Finance lease cost:
Amortization of right-of-use assets	$ 9,368	$ 8,341	$ 16,988	$ 13,178
Interest on lease liabilities	445	155	862	273
Total lease cost	15,112	13,943	28,313	24,236
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	(5,341)	(5,199)	(10,662)	(10,364)
Financing cash flows from finance leases	(7,724)	(5,786)	(14,744)	(11,455)
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 6,898	30,111	20,881	46,865
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 377	$ 6,805	$ 589
Weighted-average remaining lease term - finance leases	2 years 3 months 7 days	2 years 10 months 2 days	2 years 3 months 7 days	2 years 10 months 2 days
Weighted-average remaining lease term - operating leases	6 years 8 months 23 days	6 years 9 months 21 days	6 years 8 months 23 days	6 years 9 months 21 days
Weighted-average discount rate - finance leases	2.40%	2.49%	2.40%	2.49%
Weighted-average discount rate - operating leases	2.76%	2.76%	2.76%	2.76%
Instructional Costs and Services
Finance lease cost:
Operating lease cost	$ 3,931	$ 3,935	$ 7,866	$ 7,881
Short-term lease cost	16	94	35	157
Sublease income	(247)	(251)	(579)	(503)
Selling, general and administrative expenses
Finance lease cost:
Operating lease cost	1,777	1,644	3,443	3,231
Short-term lease cost	4	221	9	443
Sublease income	$ (182)	$ (196)	$ (311)	$ (424)