Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Revenue	$ 550,785	$ 477,915	$ 1,051,537	$ 945,513
Total costs and expenses	461,263	393,971	881,696	786,355
Total assets	2,841,584		2,841,584		$ 2,521,164
Depreciation and amortization	18,998	17,870	35,617	36,355
Related Party
Segment Reporting Information [Line Items]
Shared service fee from related party	3,500	3,800	7,200	7,700
Reportable Segment
Segment Reporting Information [Line Items]
Revenue	550,785	477,915	1,051,537	945,513
Personnel expenses	307,466	265,087	589,124	533,459
Facility expenses	51,292	45,038	99,674	88,843
Other expenses	77,009	66,190	145,062	125,469
Total costs and expenses	435,767	376,315	833,860	747,771
Segment Adjusted EBITDA	115,018	101,600	217,677	197,742
Total assets	2,841,584	2,363,338	2,841,584	2,363,338
Purchases of property and equipment	25,226	15,263	40,958	32,494
Depreciation and amortization	18,998	17,870	35,617	36,355
Reportable Segment | Related Party
Segment Reporting Information [Line Items]
Shared service fee from related party	$ 3,500	$ 3,800	$ 7,200	$ 7,700