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Insurance Premiums (Roll Forward Of Premiums Receivable) (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013
Insurance Premiums [Abstract] |  |  |
Premiums Receivable, Beginning balance | $ 1,051 us-gaap_PremiumsReceivableAtCarryingValue |  | $ 1,228 us-gaap_PremiumsReceivableAtCarryingValue
Premium Payments Received | (120)us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivablePremiumPaymentsReceived |  | (135)us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivablePremiumPaymentsReceived
Premiums from New Business Written | 6 us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivableNewBusinessWritten |  | 0 us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivableNewBusinessWritten
Adjustments, Changes in Expected Term of Policies | (50)us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentChangeInPeriodOfContract |  | (45)us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentChangeInPeriodOfContract
Adjustments, Accretion of Premiums Receivable Discount | 26 us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentAccretionOfDiscountOnPremiumReceivable |  | 28 us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentAccretionOfDiscountOnPremiumReceivable
Adjustments, Other | (38)us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentOtherAdjustments | [1] | (25)us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentOtherAdjustments
Premiums Receivable, Ending balance | $ 875 us-gaap_PremiumsReceivableAtCarryingValue |  | $ 1,051 us-gaap_PremiumsReceivableAtCarryingValue
[1] | Primarily consists of unrealized gains (losses) due to foreign currency exchange rates.

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- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of new business written on financial guarantee insurance contracts. + References No definition available. + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivableNewBusinessWritten
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Amount of premium payments received during the period for premiums receivable on financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivablePremiumPaymentsReceived
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition This element represents the accretion of the discount for premiums receivable on financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iii) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition This element represents adjustments to the premium receivable related to financial guarantee insurance contracts due to changes in the period of the contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(i) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentChangeInPeriodOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition This element represents other adjustments to premiums receivable on financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iv) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition The carrying amount as of the balance sheet date due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, net of the allowance for doubtful accounts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),5) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 5 -Article 7 + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | debit
Period Type: | instant