Segment Reporting - Summary of Assets by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Consolidated assets	$ 19,110,252	$ 18,974,536
Equity method and other investments	224,611	245,534
Property and equipment, net	3,393,669	3,149,213
U.S. dialysis and related lab services
ASSETS
Consolidated assets	12,333,641	11,802,131
Equity method and other investments	95,290	84,866
Other ancillary services and strategic initiatives
ASSETS
Consolidated assets	1,387,046	1,410,763
Equity method and other investments	129,321	160,668
DMG - Held for sale
ASSETS
Consolidated assets	5,389,565	5,761,642
Equity method and other investments	4,833	10,321
Non-US | Other ancillary services and strategic initiatives
ASSETS
Property and equipment, net	$ 136,052	$ 125,932