XML 88 R96.htm IDEA: XBRL DOCUMENT v2.4.0.8

Long-Term Employee Benefit Liabilities - Asset Allocation of Defined Benefit Pension Plans (Detail) (Pension Plan, Defined Benefit [Member])	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014 Subsequent [Member] Minimum [Member]	Dec. 31, 2014 Subsequent [Member] Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Equity securities	58.00%	57.00%	55.00%	75.00%
Fixed income securities	41.00%	42.00%	25.00%	45.00%
Cash and cash equivalents	1.00%	1.00%	0.00%	15.00%
Total	100.00%	100.00%		100.00%

X

- Definition

Defined benefit plan cash and cash equivalents.

+ References

No definition available.

+ Details

Name:	mga_DefinedBenefitPlanCashAndCashEquivalents
Namespace Prefix:	mga_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Defined benefit plans target allocation percentage.

+ References

No definition available.

+ Details

Name:	mga_DefinedBenefitPlansTargetAllocationPercentage
Namespace Prefix:	mga_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Defined Benefit Plan Target Allocation Percentage Of Assets Debt Fixed Income Securities

+ References

No definition available.

+ Details

Name:	mga_DefinedBenefitPlanTargetAllocationPercentageOfAssetsDebtFixedIncomeSecurities
Namespace Prefix:	mga_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e2446-114920



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant