General (Details 9) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
General
Projected fees Under Affordable Care Act			$ 27.7
Fees Under Affordable Care Act Expense	6.9mgln_FeesUnderAffordableCareActExpense	5.1mgln_FeesUnderAffordableCareActExpense		21.4mgln_FeesUnderAffordableCareActExpense
Amount of Revenues Associated with Accrual for Reimbursement of Economic Impact of Affordable Care Act Fees from its Customers	$ 11.7	$ 3.2

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