Acquisitions and Divestitures - Additional Information (Details)			1 Months Ended	3 Months Ended		12 Months Ended
	May 01, 2017 USD ($) state patient clinic	Aug. 01, 2016 USD ($)	Dec. 31, 2012 clinic	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($) clinic	Dec. 31, 2016 USD ($) clinic	Dec. 31, 2015 USD ($) clinic	Sep. 30, 2017 USD ($)	Aug. 01, 2017 USD ($)
Business Acquisition [Line Items]
Cash paid to acquire business						$ 803,879,000	$ 563,856,000	$ 96,469,000
Contingent earn-out obligations associated with acquisitions						2,692,000
Contingent earn-out obligations						11,466
Fair value of contingent earn-out consideration						6,388,000	2,950,000
Other Accrued Liabilities
Business Acquisition [Line Items]
Fair value of contingent earn-out consideration						216,000
Other long-term liabilities
Business Acquisition [Line Items]
Fair value of contingent earn-out consideration						6,172,000
Other companies
Business Acquisition [Line Items]
Fair value of contingent earn-out consideration						$ 6,388,000
Minimum | Other companies | EBITDA or Operating Income Performance Targets or Quality Margins
Business Acquisition [Line Items]
Earn-out consideration payment period						2 years
Maximum | Other companies | EBITDA or Operating Income Performance Targets or Quality Margins
Business Acquisition [Line Items]
Earn-out consideration payment period						6 years
Renal Ventures Limited, LLC
Business Acquisition [Line Items]
Ownership interest percentage	100.00%
Cash paid to acquire business	$ 359,913
Number of dialysis clinic patients | patient	2,600
Number of states where dialysis centers are located | state	6
Proceeds from divestiture of business	$ 21,219
Business acquisition, transaction costs									$ 11,950
Amortizable intangible assets acquired, weighted-average estimated useful lives						5 years
Goodwill deductible for tax purposes associated with acquisitions						$ 298,200
Series of individually immaterial business acquisitions
Business Acquisition [Line Items]
Cash paid to acquire business						$ 308,550	$ 165,108	$ 54,551
Number of businesses acquired | clinic			2
Amortizable intangible assets acquired, weighted-average estimated useful lives						7 years	7 years	11 years
Goodwill deductible for tax purposes associated with acquisitions						$ 237,363,000	$ 169,379,000	$ 43,823,000
Contingent earn-out obligations associated with acquisitions						2,692	1,511
Liabilities assumed						$ 23,748	$ 17,963	$ 7,452
U S Dialysis And Related Lab Services | Series of individually immaterial business acquisitions
Business Acquisition [Line Items]
Number of businesses acquired | clinic						30	8	6
Foreign Dialysis Centers | Series of individually immaterial business acquisitions
Business Acquisition [Line Items]
Number of businesses acquired | clinic						68	21	21
Operating Dialysis Center | Renal Ventures Limited, LLC
Business Acquisition [Line Items]
Number of businesses acquired | clinic	36
Number of businesses divested | clinic	3
New Center Under Construction | Renal Ventures Limited, LLC
Business Acquisition [Line Items]
Number of businesses acquired | clinic	1
Number of businesses divested | clinic	1
Home Dialysis Clinic | Renal Ventures Limited, LLC
Business Acquisition [Line Items]
Number of businesses acquired | clinic	1
Khazanah And Mitsui | Asia-Pacific dialysis business
Business Acquisition [Line Items]
Ownership interest percentage		40.00%								60.00%
Initial investment in equity method investment		$ 300,000
Subscribed investment amount		$ 50,000								$ 50,000
Current economic interest										73.30%
Non-cash non-taxable gain				$ 6,293,000	$ (374,374,000)