Acquisitions - Components of Routine Acquisitions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) Clinic	Dec. 31, 2020 USD ($) Clinic	Dec. 31, 2019 USD ($) Clinic
Business Acquisition [Line Items]
Cash paid to acquire business	$ 187,050	$ 182,013	$ 100,861
Series of individually immaterial business acquisitions
Business Acquisition [Line Items]
Cash paid to acquire business	187,050	182,013	98,836
Business combination contingent consideration acquisitions, earn-outs	14,854	14,042	23,536
Deferred Purchase price and liabilities assumed	10,226	20,415	4,326
Non-cash gain on acquiring additional ownership in business acquisition	0	1,821	0
Aggregate purchase cost recognized	$ 212,130	$ 218,291	$ 126,698
Series of individually immaterial business acquisitions | U.S. dialysis
Business Acquisition [Line Items]
Number of businesses acquired | Clinic	19	8	7
Series of individually immaterial business acquisitions | Foreign Dialysis Centers
Business Acquisition [Line Items]
Number of businesses acquired | Clinic	17	66	16