Goodwill - Schedule of Goodwill Impairment Charges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Goodwill [Line Items]
Goodwill impairment charges	$ 601,040	$ 0	$ 686,355	$ 253,000	$ 281,415
DMG
Goodwill [Line Items]
Goodwill impairment charges			651,659		$ 253,000
Vascular Access Clinic
Goodwill [Line Items]
Goodwill impairment charges	0	0	34,696	0
CALIFORNIA | DMG
Goodwill [Line Items]
Goodwill impairment charges	560,756	0	560,756	0
FLORIDA | DMG
Goodwill [Line Items]
Goodwill impairment charges	26,324	0	76,270	91,200
NEW MEXICO | DMG
Goodwill [Line Items]
Goodwill impairment charges	13,960	0	14,633	0
NEVADA | DMG
Goodwill [Line Items]
Goodwill impairment charges	$ 0	$ 0	$ 0	$ 161,800