XML 95 R68.htm IDEA: XBRL DOCUMENT v3.7.0.1

Equity Investments Acquired as Part of Business Combination (Detail) $ in Millions	Dec. 31, 2016 USD ($)
Getrag Ford Transmission GmbH ["GFT"] [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Investment balance	$ 340
Getrag (Jiangxi) Transmission Co., Ltd [GJT] [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Investment balance	$ 1,077
Dongfeng Getrag Transmission Co. Ltd ["DGT"] [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Investment balance	$ 80

X

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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

X

- Definition

Fair value portion of investments accounted under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=66022186&loc=d3e32014-111567

+ Details

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

X

- 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

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

X

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mga_GetragFordTransmissionGmbhMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mga_GetragJiangxiTransmissionCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mga_DongfengGetragTransmissionCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: