Segment reporting - Summary of Expenditures for Property and Equipment by Segment (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 245,740	$ 272,204
Segment, Expenditure, Addition to Long-Lived Assets	245,740	272,204
U.S. dialysis
Segment Reporting Information [Line Items]
Segment, Expenditure, Addition to Long-Lived Assets	211,171	240,474
Other—Ancillary services
Segment Reporting Information [Line Items]
Segment, Expenditure, Addition to Long-Lived Assets	$ 34,569	$ 31,730