Organization and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($)	Dec. 31, 2017 state patient segment Country outpatient_dialysis_center entity
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Operating divisions | segment		2
Percentage of risk on revenue		1.00%
Number of legal entities that third parties held noncontrolling equity interests | entity		589
Minimum | Noncompetition and other agreements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Amortization period		2 years
Minimum | Buildings
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Property, and equipment useful lives		20 years
Minimum | Equipment and Information Systems
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Property, and equipment useful lives		3 years
Maximum | Noncompetition and other agreements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Amortization period		10 years
Maximum | Buildings
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Property, and equipment useful lives		40 years
Maximum | Equipment and Information Systems
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Property, and equipment useful lives		8 years
United States
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of dialysis centers that the company operated or provided administrative services | outpatient_dialysis_center		2,510
Number of states where dialysis centers are located | state		46
Number of patients served | patient		197,800
International Operations
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of dialysis centers that the company operated or provided administrative services | outpatient_dialysis_center		237
Number of patients served | patient		22,900
Number of countries in which dialysis centers located | Country		11
Continuing Operations
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of legal entities that third parties held noncontrolling equity interests | entity		586
ASU 2015-04, ASU 2016-08, ASU 2016-10, ASU 2016-11, ASU 2016-12 | Difference Between Revenue Guidance In Effect Before And After Topic 606 | Scenario, Forecast
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Projected benefit to be recognized | $	$ 30,000