Discontinued Operations and Assets Held for Sale - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Sep. 11, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on Brazil held-for-sale disposal group		$ 65,137,000	$ 448,852,000
Discontinued Operations, Disposed of by Sale | Walden e-Learning, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from dispositions				$ 1,480,000,000
Brazil | Anima | Discontinued Operations | Rede
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on Brazil held-for-sale disposal group	$ 32,400,000