Significant Accounting Policies - Impact of Adoption on Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tuition receivable, net	$ 41,004	$ 51,523
Deferred income tax liabilities	40,107	47,942
Retained earnings	$ 192,072	152,819
Cumulative Effect, Period of Adoption, Adjusted Balance
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
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)