Noncontrolling Interests Subject to Put Provisions and Other Commitments - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Epogen
Commitments And Contingencies Disclosure [Line Items]
Long term purchase commitment, expiration date	Dec. 31, 2022
Dialysis Equipment, Parts and Supplies
Commitments And Contingencies Disclosure [Line Items]
Long term purchase commitment, expiration date		Dec. 31, 2020
Purchase commitment, purchase during the period		$ 182,446	$ 176,212	$ 164,766
Hemodialysis Products, Supplies and Equipment
Commitments And Contingencies Disclosure [Line Items]
Purchase commitment, purchase during the period		$ 162,858	$ 166,764	$ 162,109
Minimum
Commitments And Contingencies Disclosure [Line Items]
Scheduled dissolution term of joint ventures		10 years
Minimum | Epogen
Commitments And Contingencies Disclosure [Line Items]
Long-term purchase commitment, percentage of quantity required	90.00%
Maximum
Commitments And Contingencies Disclosure [Line Items]
Scheduled dissolution term of joint ventures		50 years
Commitments to Provide Operating Capital
Commitments And Contingencies Disclosure [Line Items]
Other potential commitments to provide operating capital to several dialysis centers		$ 4,675