Goodwill - Changes in Goodwill by Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance			$ 6,787,635	$ 6,841,960	$ 6,841,960
Acquisitions			110,248		90,226
Impairment charges	$ 0	$ (83,855)	0	(124,892)	(124,892)
Foreign currency and other adjustments			(21,213)		(19,659)
Divestitures			(8,293)
Ending balance	6,868,377		6,868,377		6,787,635
Goodwill, before accumulated impairment charges	6,998,809		6,998,809
Accumulated impairment charges	(130,432)		(130,432)
Ending balance	6,868,377		6,868,377		6,787,635
U.S. dialysis
Goodwill [Roll Forward]
Beginning balance			6,287,100	6,275,004	6,275,004
Acquisitions			24,377		18,089
Impairment charges					0
Foreign currency and other adjustments			0		(5,993)
Divestitures			(1,549)
Ending balance	6,309,928		6,309,928		6,287,100
Goodwill, before accumulated impairment charges	6,309,928		6,309,928
Accumulated impairment charges	0		0
Ending balance	6,309,928		6,309,928		6,287,100
Other—Ancillary services
Goodwill [Roll Forward]
Beginning balance			500,535	$ 566,956	566,956
Acquisitions			85,871		72,137
Impairment charges					(124,892)
Foreign currency and other adjustments			(21,213)		(13,666)
Divestitures			(6,744)
Ending balance	558,449		558,449		500,535
Goodwill, before accumulated impairment charges	688,881		688,881
Accumulated impairment charges	(130,432)		(130,432)
Ending balance	$ 558,449		$ 558,449		$ 500,535