Net Income (Loss) per Common Share Attributable to Magellan Helath Services, Inc (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net income (loss) attributable to Magellan Health, Inc.	$ (7,808)	$ 27,133	$ 4,123	$ 57,839
Denominator:
Weighted average number of common shares outstanding-basic (in shares)	24,892	26,703	25,297	27,070
Common stock equivalents-stock options (in shares)		404	360	517
Common stock equivalents-RSAs (in shares)		133	640	77
Common stock equivalents-RSUs (in shares)			34	18
Common stock equivalents- PSUs( in shares)			39
Common stock equivalents-employee stock purchase plan (in shares)		2	2	2
Weighted average number of common shares outstanding-diluted (in shares)	24,892	27,242	26,372	27,684
Net income (loss) attributable to Magellan Health, Inc. per common share-basic (in dollars per share)	$ (0.31)	$ 1.02	$ 0.16	$ 2.14
Net income (loss) attributable to Magellan Health, Inc. per common share-diluted (in dollars per share)	$ (0.31)	$ 1.00	$ 0.16	$ 2.09
Potential dilutive securities excluded from computation of dilutive securities (in shares)	1,400	700	1,100	600