General - Leases - Gross Difference (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Leases
Total lease payments	$ 52,879
Less interest	(1,525)
Present value of lease liabilities	$ 51,354

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating and finance leases.

No definition available.

Name:	mgln_LeaseLiabilityUndiscountedExcessAmount
Namespace Prefix:	mgln_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant