Goodwill - Changes in Goodwill by Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance			$ 6,841,960	$ 6,610,279	$ 6,610,279
Acquisitions			77,238		278,348
Divestitures					(15,497)
Impairment charges	$ (83,855)	$ 0	(124,892)	(3,106)	(3,106)
Foreign currency and other adjustments			(28,647)		(28,064)
Ending balance	6,765,659		6,765,659		6,841,960
Goodwill, before accumulated impairment charges	6,915,400		6,915,400
Accumulated impairment charges	(149,741)		(149,741)
Ending balance	6,765,659		6,765,659		6,841,960
U.S. dialysis and related lab services
Goodwill [Roll Forward]
Beginning balance			6,275,004	6,144,761	6,144,761
Acquisitions			18,089		130,574
Divestitures					(331)
Impairment charges			0		0
Foreign currency and other adjustments			0		0
Ending balance	6,293,093		6,293,093		6,275,004
Goodwill, before accumulated impairment charges	6,293,093		6,293,093
Accumulated impairment charges	0		0
Ending balance	6,293,093		6,293,093		6,275,004
Other—Ancillary services and strategic initiatives
Goodwill [Roll Forward]
Beginning balance			566,956	$ 465,518	465,518
Acquisitions			59,149		147,774
Divestitures					(15,166)
Impairment charges	(83,855)		(124,892)		(3,106)
Foreign currency and other adjustments			(28,647)		(28,064)
Ending balance	472,566		472,566		566,956
Goodwill, before accumulated impairment charges	622,307		622,307
Accumulated impairment charges	(149,741)		(149,741)
Ending balance	$ 472,566		$ 472,566		$ 566,956