Goodwill and Intangible Assets - Summary of Intangible Assets, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 567,195	$ 299,068
Accumulated Amortization	(142,976)	(100,932)
Net Carrying Value	424,219	198,136
Physician And Hospital Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	265,465	216,458
Accumulated Amortization	(130,050)	(98,145)
Net Carrying Value	$ 135,415	$ 118,313
Weighted Average Amortization Period (in years)	4 months 24 days	9 months 18 days
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 248,880	$ 75,460
Accumulated Amortization	(10,612)	(2,634)
Net Carrying Value	$ 238,268	$ 72,826
Weighted Average Amortization Period (in years)	9 years 10 months 24 days	7 years 2 months 12 days
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 28,620	$ 7,150
Accumulated Amortization	(597)	(153)
Net Carrying Value	$ 28,023	$ 6,997
Weighted Average Amortization Period (in years)	1 year 2 months 12 days	8 months 12 days
Patented Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 24,230
Accumulated Amortization	(1,717)
Net Carrying Value	$ 22,513
Weighted Average Amortization Period (in years)	7 months 6 days