Net Income per Common Share Attributable to Magellan Helath, Inc (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income attributable to Magellan Health, Inc.	$ 17,747	$ 13,237
Denominator:
Weighted average number of common shares outstanding-basic (in shares)	23,012	23,631
Common stock equivalents-stock options (in shares)	474	253
Common stock equivalents-RSAs (in shares)	402	563
Common stock equivalents-RSUs (in shares)	81	27
Common stock equivalents- PSUs( in shares)	66	35
Common stock equivalents-employee stock purchase plan (in shares)	3	2
Weighted average number of common shares outstanding-diluted (in shares)	24,038	24,511
Net income attributable to Magellan Health, Inc. per common share-basic (in dollars per share)	$ 0.77	$ 0.56
Net income attributable to Magellan Health, Inc. per common share-diluted (in dollars per share)	$ 0.74	$ 0.54
Potential dilutive securities excluded from computation of dilutive securities (in shares)	600	1,500