Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Useful life - acquired			3 years
Amortization expenses	$ 19,392,000	$ 15,417,000	$ 38,799,000	$ 30,834,000
Trade names
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Impairment of intangible assets	$ 0	$ 0	0	0
Student relationships
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Amortization expenses			$ 33,800,000	$ 27,700,000