The number of days required for a customer to have the right to terminate a contract for cause.

No definition available.

Name:	mgln_TerminationClauseNumberOfDaysNoticeToTerminate
Namespace Prefix:	mgln_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of days required for a customer to have the right to terminate a contract without cause after January 1, 2014.

+ References

No definition available.

+ Details

Name:	mgln_TerminationClauseNumberOfDaysNoticeToTerminateWithoutCause
Namespace Prefix:	mgln_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_MajorCustomersAxis=mgln_FloridaContractsMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorCustomersAxis=mgln_IowaContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=mgln_PharmacySolutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorCustomersAxis=mgln_CustomerAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_SalesRevenueServicesNetMember
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- Details

Name:	us-gaap_MajorCustomersAxis=mgln_CustomerBMember
Namespace Prefix:
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Summary of Significant Accounting Policies - Significant Customers (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant customers
Revenues	$ 1,694,415	$ 1,419,406	$ 1,419,139	$ 1,305,623	$ 1,263,385	$ 1,292,132	$ 1,164,345	$ 1,117,022	$ 5,838,583	$ 4,836,884	$ 4,597,400
Florida Contract
Significant customers
Termination notice									1 day
Termination notice period without cause									30 days
Revenues									$ 605,900	548,700	439,500
Iowa Contracts
Significant customers
Revenues										13,500	530,300
Pharmacy Management \| Customer A \| Service
Significant customers
Revenues									4,764	264,152	$ 324,809
Pharmacy Management \| Customer B \| Service
Significant customers
Revenues									$ 346,405	$ 152,218