Segment reporting - Summary of Expenditures for Property and Equipment by Segment (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 449,896	$ 547,183
U.S. dialysis
Segment Reporting Information [Line Items]
Expenditures for property and equipment	430,646	477,533
Other—Ancillary services
Segment Reporting Information [Line Items]
Expenditures for property and equipment	19,250	31,184
DMG - Discontinued operations
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 0	$ 38,466