Discontinued Operations - Components of Income from Discontinued Operations - Additional Information (Details) - MCC Business - Discontinued Operations, Held-for-sale - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Discontinued Operations
Stock compensation expense		$ 260
Overhead expenses previously allocated		$ 6,700
Divestiture related expenses	$ 605

Amount of overhead expenses previously allocated attributable to disposal group, including, but not limited to, discontinued operation.

No definition available.

Name:	mgln_DisposalGroupIncludingDiscontinuedOperationOverheadExpensesPreviouslyAllocated
Namespace Prefix:	mgln_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration