Net Income per Common Share Attributable to Magellan Helath Services, Inc (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:
Net income attributable to Magellan Health, Inc.	$ 27,133	$ 47,232	$ 57,839	$ 106,770
Denominator:
Weighted average number of common shares outstanding-basic (in shares)	26,703,000	26,990,000	27,070,000	26,976,000
Common stock equivalents-stock options (in shares)	404,000	655,000	517,000	539,000
Common stock equivalents-restricted stock (in shares)	133,000	4,000	77,000	11,000
Common stock equivalents-restricted stock units (in shares)		54,000	18,000	35,000
Common stock equivalents-employee stock purchase plan (in shares)	2,000	1,000	2,000	2,000
Weighted average number of common shares outstanding-diluted (in shares)	27,242,000	27,704,000	27,684,000	27,563,000
Net income attributable to Magellan Health, Inc. per common share-basic (in dollars per share)	$ 1.02	$ 1.75	$ 2.14	$ 3.96
Net income attributable to Magellan Health, Inc. per common share-diluted (in dollars per share)	$ 1.00	$ 1.70	$ 2.09	$ 3.87
Potential dilutive securities excluded from computation of dilutive securities (in shares)	700,000	900,000	600,000	900,000