General - Health Care Reform (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
HIF fees	$ 36.2
Accrued Liabilities
HIF fees	12.4
Liabilities Held For Sale
HIF fees	$ 23.8

Affordable Care Act (ACA) fiscal year annual fees paid during the period.

No definition available.

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