Goodwill and Intangibles- Summary of Changes in Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	$ 325,137	$ 134,610
Finite-lived Intangible Assets Acquired	192,352
Amortization expense of definite lived assets	1,054
Indefinite-lived Intangible Assets, Period Increase (Decrease)	(771)
Trade name
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	195,648	78,299
Certificates of need/licenses
Finite And Infinite Lived Intangible Assets [Line Items]
Indefinite-lived assets, carrying amount	111,778	53,493
Indefinite-lived Intangible Assets Acquired	59,056
Indefinite-lived Intangible Assets, Period Increase (Decrease)	(771)
Trade name
Finite And Infinite Lived Intangible Assets [Line Items]
Definite-lived assets, gross carrying amount		2,580
Indefinite-lived Intangible Assets Acquired	117,349
Amortization expense of definite lived assets	739
Definite-lived assets, net carrying amount	1,841
Customer Relationships
Finite And Infinite Lived Intangible Assets [Line Items]
Definite-lived assets, gross carrying amount		0
Finite-lived Intangible Assets Acquired	15,856
Amortization expense of definite lived assets	127
Definite-lived assets, net carrying amount	15,729
Non-compete agreements
Finite And Infinite Lived Intangible Assets [Line Items]
Definite-lived assets, gross carrying amount		$ 238
Finite-lived Intangible Assets Acquired	91
Amortization expense of definite lived assets	188
Definite-lived assets, net carrying amount	$ 141