Acquisitions and Joint Ventures - Schedule of Aggregate Consideration Paid and Recognized Identified Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Payments to Acquire Businesses	$ 75,028
Recognized amounts of identifiable assets acquired and liabilities assumed
Patient account receivable	5,679
Other assets and (liabilities), net	2,143
Total identifiable assets	42,273
Noncontrolling interest	53,657
Goodwill, including noncontrolling interest of $34,409	86,412
Goodwill related to noncontrolling interests	34,409	$ 1,275
Licensing Agreements [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed
Certificates of needs/licenses	20,207
Trade Names [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed
Business acquisition, purchase price allocation, Intangible Assets	14,238
Other Identifiable Intangible Assets [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed
Business acquisition, purchase price allocation, Intangible Assets	$ 6