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Goodwill and Intangible Assets - Schedule of Goodwill (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Changes in carrying amount
Balance, beginning of period			$ 1,318,526,000
Reporting unit reallocation			0
Additions			0
Impairments	$ 0	$ 0	0	$ 0
Currency translation adjustments			(38,567,000)
Adjustments to prior acquisitions			262,000
Balance, end of period	1,280,221,000		1,280,221,000
U.S. Higher Education
Changes in carrying amount
Balance, beginning of period			732,075,000
Reporting unit reallocation			(100,000,000)
Additions			0
Impairments			0
Currency translation adjustments			0
Adjustments to prior acquisitions			0
Balance, end of period	632,075,000		632,075,000
Australia / New Zealand
Changes in carrying amount
Balance, beginning of period			586,451,000
Reporting unit reallocation			0
Additions			0
Impairments			0
Currency translation adjustments			(38,567,000)
Adjustments to prior acquisitions			262,000
Balance, end of period	548,146,000		548,146,000
Alternative Learning
Changes in carrying amount
Balance, beginning of period			0
Reporting unit reallocation			100,000,000
Additions			0
Impairments			0
Currency translation adjustments			0
Adjustments to prior acquisitions			0
Balance, end of period	$ 100,000,000		$ 100,000,000