Goodwill and Intangibles- Summary of Changes in Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	$ 128,363	$ 97,999
Definite-lived assets, gross carrying amount	15,023	14,975
Intangible assets, gross carrying amount	143,386	112,974
Definite-lived assets, accumulated amortization	(12,607)	(10,968)
Definite-lived assets, net carrying amount	2,416	4,007
Intangible assets, net carrying amount	130,779	102,006
Certificates of need/licenses
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	49,773	33,327
Trade names
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	78,590	64,672
Definite-lived assets, gross carrying amount	9,291	9,294
Definite-lived assets, accumulated amortization	(7,184)	(5,991)
Definite-lived assets, net carrying amount	$ 2,107	$ 3,303
Trade names | Minimum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	2 months	8 months
Trade names | Maximum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	9 years	9 years
Non-compete agreements
Finite And Infinite Lived Intangible Assets [Line Items]
Definite-lived assets, gross carrying amount	$ 5,732	$ 5,681
Definite-lived assets, accumulated amortization	(5,423)	(4,977)
Definite-lived assets, net carrying amount	$ 309	$ 704
Non-compete agreements | Minimum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	2 months	2 months
Non-compete agreements | Maximum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	2 years	3 years