Loss Per Common Share - Computation of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Loss from continuing operations	$ (5,350)	$ (11,190)
Income from discontinued operations, net of tax	0	1,383
Net loss attributable to common shareholders of Evolent Health, Inc. - Basic	(5,350)	(9,807)
Net loss attributable to common shareholders of Evolent Health, Inc. - Diluted	$ (5,350)	$ (9,807)
Weighted-average common shares outstanding - basic (in shares)	89,509	84,670
Weighted-average common shares outstanding - diluted (in shares)	89,509	84,670
Loss per common share, Basic and diluted
Basic (in dollars per share)	$ (0.06)	$ (0.13)
Continuing operations, diluted (in dollars per share)	(0.06)	(0.13)
Discontinued operations, diluted (in dollars per share)	0	0.01
Discontinued operations, basic (in dollars per share)	0	0.01
Diluted loss per share attributable to common shareholders of Evolent Health, Inc. (in dollars per share)	(0.06)	(0.12)
Basic loss per share attributable to common shareholders of Evolent Health, Inc. (in dollars per share)	$ (0.06)	$ (0.12)