Goodwill and Intangible Assets - Summary of Intangible Assets, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 906,681	$ 871,821
Accumulated Amortization	(266,753)	(203,292)
Net Carrying Value	639,928	668,529
Physician And Hospital Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	381,635	347,862
Accumulated Amortization	(203,915)	(168,488)
Net Carrying Value	177,720	179,374
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	443,300	443,300
Accumulated Amortization	(48,837)	(27,368)
Net Carrying Value	394,463	415,932
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	43,156	43,156
Accumulated Amortization	(2,933)	(1,604)
Net Carrying Value	40,223	41,552
Patented and Other Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	38,590	37,503
Accumulated Amortization	(11,068)	(5,832)
Net Carrying Value	$ 27,522	$ 31,671

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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