Segment Reporting - Reconciliation of Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting [Abstract]
Net loss attributable to common shareholders of Evolent Health, Inc.	$ 78,752	$ 46,739
Interest income	919	1,060
Interest expense	(6,285)	(3,562)
(Provision) benefit for income taxes	(270)	496
Depreciation and amortization expenses	(16,138)	(14,266)
Impairment	(47,133)	0
Loss from equity method investees	(412)	(424)
Loss on disposal of assets	(6,447)	0
Change in fair value of contingent consideration and indemnification asset	3,818	(100)
Other income (expense), net	(71)	427
Net loss attributable to non-controlling interests	0	1,910
Purchase accounting adjustments	0	(596)
Stock-based compensation expense	(3,508)	(4,537)
Severance costs	(6,103)	(10,602)
Amortization of contract cost assets	(440)	(754)
Acquisition costs	(309)	(1,013)
Adjusted EBITDA	$ 3,627	$ (14,778)