Reinsurance (Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts - Narrative) (Detail) - USD ($) $ in Millions	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Guaranteed Minimum Death Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
GLB liability	$ 120		$ 117
Guaranteed Minimum Income Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
GLB liability	853		888		$ 663		$ 427
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	559	[1]	609	[1],[2]	$ 406	[2],[3]	$ 193	[3]
Level 3 | Guaranteed Minimum Income Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 559	[4]	$ 609

[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 c) for additional information.

[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 $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 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. The liability for GLB reinsurance was $663 million at December 31, 2014 and $427 million at December 31, 2013, which includes a fair value derivative adjustment of $406 million and $193 million, respectively.

[4] 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.