Intangible Assets - Carrying Value and Amortization of Identifiable Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Total identifiable intangible assets, accumulated amortization	$ (225,634)	$ (191,707)
Total identifiable intangible assets, gross carrying amount	555,550	543,369
Total identifiable intangible assets, net carrying amount	329,916	351,662
Amortized intangible assets:
Amortization expense	31,700	31,000	$ 29,500
Estimated amortization expense
2024	23,249
2025	16,535
2026	15,385
2027	14,441
2028	13,337
Trademarks
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, gross carrying amount	5,000	5,000
Total identifiable intangible assets, accumulated amortization	(5,000)	(5,000)
Finite-lived intangible assets, net carrying amount	0	0
Customer relationships
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, gross carrying amount	317,571	310,279
Total identifiable intangible assets, accumulated amortization	(200,312)	(170,265)
Finite-lived intangible assets, net carrying amount	117,259	140,014
Non-compete agreements
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, gross carrying amount	38,262	36,729
Total identifiable intangible assets, accumulated amortization	(20,322)	(16,442)
Finite-lived intangible assets, net carrying amount	17,940	20,287
Trademarks
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets	$ 166,698	166,698
Amortized intangible assets:
Weighted average time until next renewal	5 years 8 months 12 days
Certificates of need
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets	$ 26,183	22,827
Accreditations
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets	$ 1,836	$ 1,836
Amortized intangible assets:
Weighted average time until next renewal	1 year 6 months