Segment reporting - Summary of Assets by Segment (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
ASSETS
Total assets	$ 16,727,787	$ 16,928,252
U.S. dialysis
ASSETS
Total assets	14,789,095	15,084,454
Other—Ancillary services
ASSETS
Total assets	$ 1,938,692	$ 1,843,798