Transactions - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Revenue	$ 81,326
Net income (loss)	(177,620)
Net income (loss) attributable to noncontrolling interest	(46,022)
Net income (loss) attributable to Evolent Health, Inc.	$ (131,598)
Net income (loss) available to common shareholders, basic (in dollars per share)	$ (2.63)
Net income (loss) available to common shareholders, diluted (in dollars per share)	$ (2.63)
Passport
Business Acquisition [Line Items]
Adjustment for removal of transaction costs		$ (200)			$ (300)
Passport | Recorded In 2016
Business Acquisition [Line Items]
Adjustment for removal of transaction costs			$ 300
Passport | Recorded In 2015
Business Acquisition [Line Items]
Adjustment for removal of transaction costs			200
Aldera
Business Acquisition [Line Items]
Adjustment for removal of transaction costs			(200)	$ (200)
Valence Health
Business Acquisition [Line Items]
Adjustment for removal of transaction costs			(2,700)	$ (2,700)
Adjustment for removal of contingent liability	$ (2,600)		2,600
Accelerated compensation cost	(3,900)		3,900		$ 3,900
Adjustment for removal of lease abandonment charge	$ (6,500)		$ 6,500