Significant Accounting Policies - Tuition Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Line Items]
Tuition receivable	$ 110,066	$ 100,060
Allowance for credit losses	(47,113)	(48,783)
Tuition receivable, net	62,953	51,277
Tuition receivable, noncurrent	2,673	2,466
Other assets
Accounting Policies [Line Items]
Tuition receivable, noncurrent	$ 2,700	$ 2,500