Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Leased Assets [Line Items]
Rental income under subleases	$ 1,848
Future rental receipts due from related party	5,262
Operating lease obligations that have not yet commenced	10,173
Finance lease obligations that have not yet commenced	992
Noncontrolling interests not subject to put provisions
Operating Leased Assets [Line Items]
Rent expense	12,799
Rent expense		$ 10,778	$ 10,160
Rental income under subleases	$ 975	963	853
Minimum
Operating Leased Assets [Line Items]
Lease agreements cover periods	5 years
Lease agreements renewal option period	5 years
Leases not yet commenced, lease terms	5 years
Maximum
Operating Leased Assets [Line Items]
Lease agreements cover periods	15 years
Lease agreements renewal option period	10 years
Leases not yet commenced, lease terms	15 years
Facility Space To Nephrologist Partners
Operating Leased Assets [Line Items]
Rental income under subleases	$ 1,848	$ 1,709	$ 1,515