Segment reporting - Summary of Assets by Segment (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
ASSETS
Total assets	$ 17,087,010	$ 17,121,488
U.S. dialysis
ASSETS
Total assets	15,227,817	15,375,000
Other—Ancillary services
ASSETS
Total assets	$ 1,859,193	$ 1,746,488