Goodwill and Intangibles- Summary of Changes in Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	$ 132,374		$ 131,792
Definite-lived assets, gross carrying amount	15,950		15,859
Intangible assets, gross carrying amount	148,324		147,651
Definite-lived assets, accumulated amortization	(13,482)		(13,041)
Definite-lived assets, net carrying amount	2,468		2,818
Intangible assets, net carrying amount	134,842		134,610
Certificates of need/licenses
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	53,579		53,493
Trade names
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	78,795		78,299
Definite-lived assets, gross carrying amount	10,127		10,127
Definite-lived assets, accumulated amortization	(7,917)		(7,547)
Definite-lived assets, net carrying amount	$ 2,210		2,580
Trade names | Minimum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	1 month	4 months
Trade names | Maximum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	9 years	10 years
Non-compete agreements
Finite And Infinite Lived Intangible Assets [Line Items]
Definite-lived assets, gross carrying amount	$ 5,823		5,732
Definite-lived assets, accumulated amortization	(5,565)		(5,494)
Definite-lived assets, net carrying amount	$ 258		$ 238
Non-compete agreements | Minimum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	4 months	2 months
Non-compete agreements | Maximum
Finite And Infinite Lived Intangible Assets [Line Items]
Estimated useful life	3 years	2 years