Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Useful life - acquired	3 years
Amortization expenses	$ 19,407,000	$ 15,417,000
Trade names
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Impairment of intangible assets	0	0
Student relationships
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Amortization expenses	$ 16,900,000	$ 13,800,000