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Pension and Other Postretirement Benefits - Schedule of Reconciliation of Activity for Investments (Detail) (Pension and Other Postretirement Benefit Plans' Assets [Member], USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011
Pension and Other Postretirement Benefit Plans' Assets [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Balance at beginning of year | $ 2,760 | $ 1,499
Realized gains | 52 | 67
Unrealized gains | 142 | 100
Purchases | 634 | 1,221
Sales | (538) | (124)
Issuances |  |
Settlements |  |
Foreign currency translation impact | 8 | (3)
Transfers in and (or) out of Level 3 |  |
Balance at end of year | $ 3,058 | $ 2,760

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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Exchange Rate + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Issues that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(3) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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