Segment reporting - Summary of Assets by Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
ASSETS
Total assets	$ 16,961,799	$ 17,121,488
U.S. dialysis
ASSETS
Total assets	15,223,532	15,375,000
Other—Ancillary services
ASSETS
Total assets	$ 1,738,267	$ 1,746,488