Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016		Jun. 30, 2016	[3]	Dec. 31, 2015		Sep. 30, 2015	[2],[3]	Jun. 30, 2015	[3]	Dec. 31, 2014	[3]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	[1]	Actuarial model
Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	[1]	1.00%
Significant Unobservable Inputs Annuitization rate	[1]	0.00%
Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	[1]	30.00%
Significant Unobservable Inputs Annuitization rate	[1]	55.00%
Guaranteed Minimum Income Benefit [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		$ 883	[2]	$ 971		$ 609	[3]	$ 744		$ 347		$ 406
Fair Value, Inputs, Level 3 [Member] | Guaranteed Minimum Income Benefit [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		$ 883	[3]			$ 609

[1] Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.

[2] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. The liability for GLB reinsurance was $1.0 billion at September 30, 2015, and $615 million at June 30, 2015, which includes a fair value derivative adjustment of $744 million and $347 million, respectively. Assets Liabilities Nine Months EndedAvailable-for-Sale Debt Securities EquitysecuritiesShort-term investmentsOtherinvestments OtherderivativeinstrumentsGLB(1)September 30, 2016Foreign Corporatesecurities MBS (in millions of U.S. dollars) Balance–Beginning of Period$57 $174 $53 $16$—$212 $6$609Transfers into Level 39 18 — ——— ——Transfers out of Level 3(2) — — ——— ——Change in Net Unrealized Gains (Losses) included in OCI8 17 — 2—4 ——Net Realized Gains/Losses(6) (12) — 1—— 2274Purchases (2)52 472 1 236222 2—Sales(10) (48) (8) (5)—— ——Settlements(5) (15) — ——(15) (2)—Balance–End of Period$103 $606 $46 $37$62$223 $8$883Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date$(5) $(11) $— $—$—$— $2$274(1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. Refer to Note 5 for additional information.(2) Includes acquired invested assets as a result of the Chubb Corp acquisition. Assets LiabilitiesNine Months Ended Available-for-Sale Debt Securities Other investments OtherderivativeinstrumentsGLB(1)September 30, 2015 Foreign Corporatesecurities MBS Equitysecurities (in millions of U.S. dollars) Balance–Beginning of Period $22 $187 $15 $2 $204 $4$406Transfers into Level 3 29 15 — — — ——Change in Net Unrealized Gains (Losses) included in OCI (1) 1 — 2 (7) ——Net Realized Gains/Losses (1) (4) — (2) — 3338Purchases 9 38 41 2 21 ——Sales (1) (10) (1) — — ——Settlements (4) (44) (1) — (9) ——Balance–End of Period $53$183$54 $4$209 $7$744Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $(1) $(2) $— $(2) $— $3$338(1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. The liability for GLB reinsurance was $1.0 billion at September 30, 2015, and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $744 million and $406 million, respectively.

[3] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. Refer to Note 5 for additional information.