XML 100 R68.htm IDEA: XBRL DOCUMENT v2.4.1.9

Fixed Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property Plant and Equipment Useful Life and Values [Abstract]
Construction in progress expenditures	$ 843us-gaap_ConstructionInProgressGross	$ 762us-gaap_ConstructionInProgressGross

X

- Details

Name:	mga_PropertyPlantAndEquipmentUsefulLifeAndValuesAbstract
Namespace Prefix:	mga_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

Name:	us-gaap_ConstructionInProgressGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant