Non-controlling Interests (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	May 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Apr. 30, 2019	May 31, 2015
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Non-controlling interests balance as of beginning-of-year		$ 6,689
Net loss attributable to non-controlling interests		0	$ 1,910
Reclassification of non-controlling interests			0
Non-controlling interests balance as of end-of-year		0		$ 6,689
Evolent Health LLC
Noncontrolling Interest [Line Items]
Parent's ownership percentage	99.20%			100.00%	99.10%	70.30%
Non-controlling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Non-controlling interests balance as of beginning-of-year		6,689	45,532	$ 45,532
Net loss attributable to non-controlling interests		0	6,500
Net loss attributable to non-controlling interests		0	(1,910)
Reclassification of non-controlling interests		(6,689)	(22)
Non-controlling interests balance as of end-of-year		$ 0	$ 50,100	$ 6,689
Class A Common Stock | Common Stock
Noncontrolling Interest [Line Items]
Issuance of common stock (in shares)	1.6			3.1
Class B Common Stock
Noncontrolling Interest [Line Items]
Income tax expense, obligations related to exchanges				$ 1,300