Significant Accounting Policies - Impact of Accounting Standards Update Adoption (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tuition receivable, net	$ 50,169	$ 51,523
Deferred income tax liabilities	53,407	47,942
Retained earnings	$ 179,646	152,819
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tuition receivable, net		51,523
Deferred income tax liabilities		47,942
Retained earnings		152,819
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tuition receivable, net		(4,571)
Deferred income tax liabilities		(1,261)
Retained earnings		(3,310)
Cumulative Effect, Period of Adoption, Adjusted Balance | Revision of Prior Period, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tuition receivable, net		46,952
Deferred income tax liabilities		46,681
Retained earnings		$ 149,509