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Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts (Narrative) (Detail) (USD $) In Millions, unless otherwise specified | 9 Months Ended |  |  |  |  |  |  |  |  |  |  |
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Sep. 30, 2014 | Sep. 30, 2014 Guaranteed Minimum Death Benefit [Member] | Dec. 31, 2013 Guaranteed Minimum Death Benefit [Member] | Sep. 30, 2014 Guaranteed Minimum Income Benefit [Member] | Dec. 31, 2013 Guaranteed Minimum Income Benefit [Member] | Sep. 30, 2013 Guaranteed Minimum Income Benefit [Member] | Jun. 30, 2013 Guaranteed Minimum Income Benefit [Member] | Dec. 31, 2012 Guaranteed Minimum Income Benefit [Member] | Sep. 30, 2014 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member] | Dec. 31, 2013 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member] | Sep. 30, 2014 Guaranteed Living Benefits [Member] | Dec. 31, 2013 Guaranteed Living Benefits [Member]
Guaranteed Minimum Benefits [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Reported liabilities |  | $ 108 | $ 100 | $ 566 | $ 427 | $ 746 | $ 880 | $ 1,400 |  |  |  |
Fair value derivative adjustment in liability |  |  |  | 317 | 193 |  |  |  |  |  |  |
Net amount at risk |  | 520 | 586 |  |  |  |  |  |  |  | 241 | 136
Mortality percentage according to Annuity 2000 mortality table |  |  |  |  |  |  |  |  |  |  | 100.00% |
Discounting assumption used in the calculation of the benefit reserve averaging - lower range |  | 2.00% |  |  |  |  |  |  | 3.50% |  | 3.50% |
Discounting assumption used in the calculation of the benefit reserve averaging - upper range |  | 3.00% |  |  |  |  |  |  | 4.50% |  | 4.50% |
Total claim amount payable, if all of the Company's cedants' policyholders covered were to die immediately |  | 629 |  |  |  |  |  |  | 39 |  |  |
GMBD net amount of risk |  |  |  |  |  |  |  |  | 75 | 73 |  |
GLB net amount of risk |  |  |  |  |  |  |  |  | $ 168 | $ 141 |  |
Average attained age of all policyholders under all benefits reinsured, years | 69 years |  |  |  |  |  |  |  |  |  |  |

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- Definition Guaranteed minimum benefit the portion of reported liabilities derived from a fair value derivative adjustment. + References No definition available. + Details
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- Definition Net amount at risk by guaranteed minimum death benefits, net amount at risk. + References No definition available. + Details
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- Definition Net amount at risk by guaranteed minimum death benefits, net amount at risk. + References No definition available. + Details
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- Definition Sum of the amount of expected guaranteed benefits in excess of the projected account balances for minimum guaranteed benefit contracts, as of the balance sheet date, net of reinsurance recoverables, for all guaranteed benefit types. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 + Details
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- Definition Percentage discount rate at the high end of a range of reasonable estimates used to calculate present value of an expected stream of future payments, which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6482852&loc=d3e14931-158439 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 + Details
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- Definition Percentage discount rate at the low end of a range of reasonable estimates used to calculate present value of an expected stream of future payments, which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6482852&loc=d3e14931-158439 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 + Details
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- Definition Actuarially determined death rate of policyholders, which is included in determining the amount of the specified guaranteed benefit obligation as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6482852&loc=d3e14931-158439 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 + Details
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- Definition Net amount at risk, representing the guaranteed benefit in excess of the current account balance corresponding to the specified product, guarantee type and subset of the guarantee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph (d)(3),(5) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 + Details
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- Definition The portion of the specified guaranteed benefit amount in excess of the sum of the current account balance amounts assuming death of the insureds, corresponding to the specified guarantee or subset of the guarantee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph (d)(3),(5) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 + Details
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- Definition Weighted average attained age of policyholders or contract holders in the specified guarantee type and subset of guarantee class, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -Subparagraph ((d)(5)) -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 + Details
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