Intangible Assets - Carrying Value and Amortization of Identifiable Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Total identifiable intangible assets, gross carrying amount	$ 513,728		$ 510,216
Finite-lived intangible assets, accumulated amortization	(108,354)		(101,148)
Total identifiable intangible assets, net carrying amount	405,374		409,068
Amortized intangible assets:
Amortization expense	6,900	$ 7,100
Trademarks
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, gross carrying amount	5,000		5,000
Finite-lived 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	288,963		287,373
Finite-lived intangible assets, accumulated amortization	(93,814)		(87,346)
Finite-lived intangible assets, net carrying amount	195,149		200,027
Non-compete agreements
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, gross carrying amount	32,845		32,114
Finite-lived intangible assets, accumulated amortization	(9,540)		(8,802)
Finite-lived intangible assets, net carrying amount	23,305		23,312
Trademarks
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets, carrying amount	$ 166,698		166,698
Amortized intangible assets:
Weighted average time until next renewal	6 years 10 months 24 days
Certificates of need
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets, carrying amount	$ 18,348		17,157
Accreditations
Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite-lived intangible assets, carrying amount	$ 1,874		$ 1,874
Amortized intangible assets:
Weighted average time until next renewal	1 year 6 months