Segment reporting - Summary of Segment Net Revenues, Segment Operating Income (Loss) and Reconciliation of Segment Income to Consolidated Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Other revenues	$ 125,620	$ 109,684	$ 254,643	$ 222,349
Total revenues	3,186,722	3,000,369	6,257,277	5,873,068
Operating income (loss)	506,398	405,291	990,243	716,936
Corporate administrative support	(25,196)	(33,864)	(55,586)	(58,452)
Debt expense	(97,747)	(103,507)	(197,165)	(204,281)
Debt prepayment, extinguishment and modification costs	(9,732)	(7,962)	(9,732)	(7,962)
Other (loss) income, net	(27,479)	1,373	(40,120)	5,125
Income before income taxes	371,440	295,195	743,226	509,818
U.S. dialysis
Segment Reporting Information [Line Items]
Total revenues	2,828,085	2,710,254	5,559,782	5,300,365
Other—Ancillary services
Segment Reporting Information [Line Items]
Total revenues	358,637	290,115	697,495	572,703
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	3,203,470	3,022,138	6,301,236	5,918,252
Operating income (loss)	531,594	439,155	1,045,829	775,388
Operating Segments | U.S. dialysis
Segment Reporting Information [Line Items]
Dialysis patient service revenues	2,835,112	2,724,211	5,585,150	5,330,192
Total revenues	2,841,010	2,730,615	5,597,171	5,342,775
Operating income (loss)	550,186	460,759	1,075,923	821,857
Operating Segments | U.S. dialysis | External Sources
Segment Reporting Information [Line Items]
Dialysis patient service revenues	2,822,187	2,703,850	5,547,761	5,287,782
Other revenues	5,898	6,404	12,021	12,583
Operating Segments | U.S. dialysis | Intersubsegment Eliminations
Segment Reporting Information [Line Items]
Dialysis patient service revenues	12,925	20,361	37,389	42,410
Operating Segments | Other—Ancillary services
Segment Reporting Information [Line Items]
Dialysis patient service revenues	238,915	186,835	454,873	362,937
Other revenues	119,722	103,280	242,622	209,766
Total revenues	362,460	291,523	704,065	575,477
Operating income (loss)	(18,592)	(21,604)	(30,094)	(46,469)
Operating Segments | Other—Ancillary services | Intersubsegment Eliminations
Segment Reporting Information [Line Items]
Dialysis patient service revenues	3,823	1,408	6,570	2,774
Intersegment Elimination
Segment Reporting Information [Line Items]
Total revenues	(16,748)	(21,769)	(43,959)	(45,184)
Intersegment Elimination | U.S. dialysis
Segment Reporting Information [Line Items]
Total revenues	(12,925)	(20,361)	(37,389)	(42,410)
Intersegment Elimination | Other—Ancillary services
Segment Reporting Information [Line Items]
Total revenues	$ (3,823)	$ (1,408)	$ (6,570)	$ (2,774)