Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Deferred revenue and student deposits	$ 23,760	$ 21,776
Scholarship assistance	68,800	54,600	$ 45,600
Future Courses
Disaggregation of Revenue [Line Items]
Deferred revenue and student deposits	23,800	21,800
Student deposit amount	$ 10,800	$ 8,900