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, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance		$ 6,841,960	$ 6,610,279
Acquisitions		90,226	278,348
Divestitures			(15,497)
Impairment charges		(124,892)	(3,106)	$ (36,196)
Foreign currency and other adjustments		(19,659)	(28,064)
Ending balance		6,787,635	6,841,960	6,610,279
Goodwill		6,940,970
Accumulated impairment charges		(153,335)
U.S. dialysis
Goodwill [Roll Forward]
Beginning balance		6,275,004	6,144,761
Acquisitions		18,089	130,574
Divestitures			(331)
Impairment charges		0	0
Foreign currency and other adjustments		(5,993)	0
Ending balance		6,287,100	6,275,004	6,144,761
Goodwill		6,287,100
Accumulated impairment charges		0
Other - Ancillary services
Goodwill [Roll Forward]
Beginning balance		566,956	465,518
Acquisitions		72,137	147,774
Divestitures			(15,166)
Impairment charges	$ (83,855)	(124,892)	(3,106)
Foreign currency and other adjustments		(13,666)	(28,064)
Ending balance		500,535	$ 566,956	$ 465,518
Goodwill		653,870
Accumulated impairment charges		$ (153,335)