General (Details 9) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
General
Health Insurer Fee (HIF) fiscal year annual fees paid during the period			$ 26.5		$ 21.4
HIF fees expensed	$ 6.7	$ 5.4	19.9	$ 16.1
Amount of revenues associated with accrual for reimbursement of economic impact of HIF fees from its customers	$ 11.6	$ 8.8	$ 34.0	$ 22.9

The amount of revenues recorded associated with the accrual for the reimbursement of the economic impact of the ACA fees from its customers.

No definition available.

Name:	mgln_AmountOfRevenuesAssociatedWithAccrualForReimbursementOfEconomicImpactOfAffordableCareActFeesFromItsCustomers
Namespace Prefix:	mgln_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration