Long Term Debt (Details) - USD ($)		6 Months Ended
	Nov. 03, 2020	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Money market funds		$ 181,024,000	$ 262,941,000	$ 213,667,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, outstanding		101,300,000		101,400,000
Interest paid		4,200,000	$ 1,200,000
Revolving Credit Facility | Australia, Dollars
Debt Instrument [Line Items]
Revolving credit facility, outstanding		$ 3,300,000		$ 3,400,000
Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Margin rate	1.50%
Unused commitment fee	0.20%
Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Margin rate	2.00%
Unused commitment fee	0.30%
Amended Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, value	$ 350,000,000
Maximum aggregate incremental term loans	$ 300,000,000
Percentage of consolidated EBITDA to be funded	100.00%
Maximum leverage ratio allowed in order to increase obligation	1.75
Debt financing costs	$ 1,900,000
Debt instrument term	5 years
Maximum total leverage ratio	2.00
Money market funds	$ 150,000,000
Minimum coverage ratio	1.75
Minimum department of education financial composite score	1.0
Minimum department of education financial composite score for two consecutive fiscal years	1.5
Amendment to the Credit Facility, Subfacility for Borrowings in Foreign Currencies | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, value	$ 150,000,000