Segment reporting - Summary of Expenditures for Property and Equipment by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 154,942	$ 198,878
U.S. dialysis and related lab services
Segment Reporting Information [Line Items]
Expenditures for property and equipment	148,763	170,548
Other—Ancillary services and strategic initiatives
Segment Reporting Information [Line Items]
Expenditures for property and equipment	6,179	8,578
DMG held for sale
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 0	$ 19,752