Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment information
Revenue	$ 1,900,192	$ 1,838,081	$ 1,724,359
Total costs and expenses	1,595,713	1,550,699	1,466,142
Total assets	2,521,164	2,333,560	2,297,235
Purchases of property and equipment	64,327	64,958	45,983
Depreciation and amortization	67,178	73,051	73,667
Reportable Segment
Segment information
Revenue	1,900,192	1,838,081	1,724,359
Personnel expenses	1,086,886	1,048,463	988,348
Facility expenses	180,996	173,375	160,817
Other expenses	255,454	254,909	240,857
Total costs and expenses	1,523,336	1,476,747	1,390,022
Segment Adjusted EBITDA	376,856	361,334	334,337
Depreciation and amortization	67,178	73,051	73,667
Related Party
Segment information
Shared service fee from related party	15,200	14,600	12,300
Related Party | Reportable Segment
Segment information
Shared service fee from related party	$ 15,200	$ 14,600	$ 12,300