EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income (loss) attributable to American Renal Associates Holdings, Inc.	$ 795	$ (8,178)	$ (6,439)	$ (18,657)
Change in the difference between the redemption value and estimated fair value for accounting purposes of the related noncontrolling interests	(444)	1,025	(703)	284
Net income (loss) attributable to common shareholders	$ 351	$ (7,153)	$ (7,142)	$ (18,373)
Weighted-average common shares outstanding, basic (in shares)	32,862,637	32,275,807	32,661,238	32,232,004
Earnings (loss) per share, basic (in USD per share)	$ 0.01	$ (0.22)	$ (0.22)	$ (0.57)
Net income (loss) attributable to common shareholders for diluted earnings per share calculation	$ 351	$ (7,153)	$ (7,142)	$ (18,373)
Weighted-average common shares outstanding, assuming dilution (in shares)	34,612,591	32,275,807	32,661,238	32,232,004
Earnings (loss) per share, diluted (in USD per share)	$ 0.01	$ (0.22)	$ (0.22)	$ (0.57)
Outstanding options and restricted stock excluded as impact would be anti-dilutive (in shares)	2,427,031	3,235,582	2,948,016	3,404,444