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Fair Value Of Financial Instruments (Realized And Unrealized Gains And Losses Included In Earnings Pertaining To Level 3 Assets And Liabilities) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended
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Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Unrealized gains (losses) on insured derivatives |  |  | $ 1,277 | $ 1,506
Net gains (losses) on financial instruments at fair value and foreign exchange | (6) | (6) | 57 | (25)
Net investment losses related to other-than-temporary impairments | 0 | (3) | 0 | (97)
Total revenues | 112 | 1,039 | 331 | 1,422
Fair Value Inputs Level 3 [Member] | Total Gains Losses Included In Earnings [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Net investment income | 0 | 0 | 0 | (5)
Unrealized gains (losses) on insured derivatives | 1,350 | 1,202 | 1,277 | 1,505
Realized gains and other settlements on insured derivatives | (1,532) | (443) | (1,521) | (463)
Net gains (losses) on financial instruments at fair value and foreign exchange | (8) | 18 | (18) | 2
Net investment losses related to other-than-temporary impairments | 0 | (3) | 0 | (60)
Total revenues | 54 | 614 | (57) | 705
Fair Value Inputs Level 3 [Member] | Change In Unrealized Gains Losses For Period Included In Earnings For Assets And Liabilities Still Held [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Net investment income | 0 | 0 | 0 | 0
Unrealized gains (losses) on insured derivatives | (162) | 641 | (218) | 571
Realized gains and other settlements on insured derivatives | 0 | 0 | 0 | 0
Net gains (losses) on financial instruments at fair value and foreign exchange | 1 | 18 | (11) | 9
Net investment losses related to other-than-temporary impairments | 0 | 0 | 0 | 0
Total revenues | 96 | 511 | 71 | 374
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Total Gains Losses Included In Earnings [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Net gains (losses) on financial instruments at fair value and foreign exchange | 244 | (160) | 205 | (274)
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Change In Unrealized Gains Losses For Period Included In Earnings For Assets And Liabilities Still Held [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Net gains (losses) on financial instruments at fair value and foreign exchange | $ 257 | $ (148) | $ 300 | $ (206)

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- Definition Change in the fair value of and realized gains and losses on financial instruments and foreign exchange included in earnings. + References No definition available. + Details
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- Definition Realized gains and losses and recognized premiums and fees related to insurance policies on derivatives included in earnings. + References No definition available. + Details
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- Definition The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It does not include realized gains and losses on investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 16 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 2 -Article 7 + Details
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- Definition The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 7 -Footnote 2 -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 15D -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 15C -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 16B -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 Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5 + Details
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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 + Details
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