Long-Term Debt - Revolving Lines Of Credit (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Letter of Credit
Line of Credit Facility [Line Items]
Outstanding letters of credit	$ 14,155
Revolver
Line of Credit Facility [Line Items]
Line of credit outstanding amount	175,000	$ 300,000
Revolving credit facilities	1,000,000
Kidney Care
Line of Credit Facility [Line Items]
Outstanding letters of credit	22,621
DMG
Line of Credit Facility [Line Items]
Outstanding letters of credit	$ 211