Segment Reporting - Summary of Expenditures for Property and Equipment by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 905,250	$ 829,095	$ 707,998
U.S. dialysis and related lab services
Segment Reporting Information [Line Items]
Expenditures for property and equipment	759,218	675,994	584,513
Other-Ancillary services and strategic initiatives
Segment Reporting Information [Line Items]
Expenditures for property and equipment	50,891	68,702	56,685
DMG - Held for sale
Segment Reporting Information [Line Items]
Expenditures for property and equipment	$ 95,141	$ 84,399	$ 66,800