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Derivative Instruments (Credit Derivatives Sold) (Detail) (USD $) In Millions, unless otherwise specified | Sep. 30, 2013 | Dec. 31, 2012
--- | --- | ---
Derivative [Line Items] |  |
Derivative notional amount | $ 33,647 | $ 58,640
Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 31,170 | 53,014
Total fair value of credit derivatives | (1,370) | (2,934)
Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Weighted average remaining expected maturity | 2 years 8 months 12 days | 5 years 1 month 6 days
Derivative notional amount | 25,771 | 47,002
Total fair value of credit derivatives | (1,355) | (2,858)
Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Weighted average remaining expected maturity | 19 years 1 month 6 days | 19 years 4 months 24 days
Derivative notional amount | 5,363 | 5,817
Total fair value of credit derivatives | (7) | (8)
Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Weighted average remaining expected maturity | 28 years 3 months 18 days | 1 year 9 months 18 days
Derivative notional amount | 36 | 195
Total fair value of credit derivatives | (8) | (68)
Credit Rating Aaa [Member] | Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 7,412 | 10,457
Total fair value of credit derivatives | (3) | (7)
Credit Rating Aaa [Member] | Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 7,412 | 10,457
Credit Rating Aaa [Member] | Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 0
Credit Rating Aaa [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 0
Credit Rating Aa [Member] | Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 3,227 | 5,965
Total fair value of credit derivatives | 0 | (70)
Credit Rating Aa [Member] | Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 3,150 | 5,862
Credit Rating Aa [Member] | Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 77 | 103
Credit Rating Aa [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 0
Credit Rating A [Member] | Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 5,399 | 8,914
Total fair value of credit derivatives | (6) | (72)
Credit Rating A [Member] | Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 1,705 | 5,253
Credit Rating A [Member] | Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 3,694 | 3,661
Credit Rating A [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 0
Credit Rating Bbb [Member] | Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 9,011 | 13,553
Total fair value of credit derivatives | (386) | (732)
Credit Rating Bbb [Member] | Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 7,419 | 11,571
Credit Rating Bbb [Member] | Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 1,592 | 1,982
Credit Rating Bbb [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 0
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 6,121 | 14,125
Total fair value of credit derivatives | (975) | (2,053)
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Credit Default Swap [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 6,085 | 13,859
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Insured Swaps [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | 0 | 71
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member] |  |
Derivative [Line Items] |  |
Derivative notional amount | $ 36 | $ 195

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Weighted Average Remaining Maturity Credit Derivatives In Years + References No definition available. + Details
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- Definition Fair value of credit risk derivative liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4K -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5708775-113959 + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | credit
Period Type: | instant

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- Details
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