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Transactions With Related Parties - Additional Information (Detail) (USD $) In Millions, unless otherwise specified |  |  |  |  | 12 Months Ended |  |  |  | 12 Months Ended
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Dec. 31, 2012 | Aug. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2010 Chief Executive Officer [Member] | Dec. 31, 2011 Related Party MID Member [Member] | Dec. 31, 2010 Related Party MID Member [Member] | Dec. 31, 2012 Honorary Chairman [Member] | Dec. 31, 2011 Honorary Chairman [Member] | Dec. 31, 2010 Honorary Chairman [Member] | Dec. 31, 2012 Trust for Benefit of Employees [Member] | Dec. 31, 2011 Trust for Benefit of Employees [Member] | Dec. 31, 2010 Trust for Benefit of Employees [Member] | Dec. 31, 2012 Related Party Companies Controlled By Stronach Group [Member] Person | Dec. 31, 2011 Related Party Companies Controlled By Stronach Group [Member]
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Company acquired |  | 27.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Cash consideration paid | $ 652 | $ 75 | $ 120 | $ 106 |  |  |  |  |  |  |  |  |  |  |
Number of trustees and members of the class of potential beneficiaries |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |
Related party expense |  |  |  |  |  | 166 | 172 | 47 | 38 | 41 |  |  |  |  |
Sales to companies controlled by the Stronach Group |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 | 36
Services to companies controlled by the Stronach Group |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 | 7
Proceeds from sale of building |  |  |  |  | 43 |  |  |  |  |  |  |  |  |  |
Amount borrowed from company to purchase common shares maximum |  |  |  |  |  |  |  |  |  |  | 18 | 35 | 31 |  |
Amount included in accounts receivable |  |  |  |  |  |  |  |  |  |  | $ 17 | $ 17 |  |  |

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