Acquisitions (Estimated Fair Values of Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Aug. 12, 2021	Jun. 30, 2021	Sep. 30, 2020
Assets acquired:
Goodwill	$ 1,328,928		$ 686,374	$ 686,480
Walden University, LLC [Member]
Assets acquired:
Cash and cash equivalents		$ 65,010
Restricted cash		18,389
Accounts receivable, net		22,091
Prepaid expenses and other current assets		8,819
Property and equipment, net		25,882
Operating lease assets		6,096
Intangible assets		833,351
Goodwill		642,554
Other assets		21,316
Total assets acquired		1,643,508
Liabilities assumed:
Accounts payable		31,971
Accrued payroll and benefits		24,376
Accrued liabilities		591
Deferred revenue		10,958
Current operating lease liabilities		1,983
Long-term operating lease liabilities		4,343
Other liabilities		4,098
Total liabilities assumed		78,320
Net assets acquired		$ 1,565,188