Goodwill - Changes in Carrying Value of Goodwill by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance		$ 6,787,635	$ 6,841,960
Acquisitions		130,057	90,226
Goodwill, Written off Related to Sale of Business Unit		(8,293)
Impairment charges		0	(124,892)	$ (3,106)
Foreign currency and other adjustments		9,710	(19,659)
Ending balance		6,919,109	6,787,635	6,841,960
Goodwill		7,055,660
Accumulated impairment charges		(136,551)
U.S. dialysis
Goodwill [Roll Forward]
Beginning balance		6,287,100	6,275,004
Acquisitions		24,377	18,089
Goodwill, Written off Related to Sale of Business Unit		(1,549)
Impairment charges			0
Foreign currency and other adjustments		0	(5,993)
Ending balance		6,309,928	6,287,100	6,275,004
Goodwill		6,309,928
Accumulated impairment charges		0
Other - Ancillary services
Goodwill [Roll Forward]
Beginning balance		500,535	566,956
Acquisitions		105,680	72,137
Goodwill, Written off Related to Sale of Business Unit		(6,744)
Impairment charges	$ (83,855)		(124,892)
Foreign currency and other adjustments		9,710	(13,666)
Ending balance		609,181	$ 500,535	$ 566,956
Goodwill		745,732
Accumulated impairment charges		$ (136,551)