Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2013 Minimum [Member]		Mar. 31, 2013 Maximum [Member]		Mar. 31, 2013 Guaranteed Minimum Income Benefit [Member]		Dec. 31, 2012 Guaranteed Minimum Income Benefit [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value							$ 753	[1]	$ 1,119
Valuation Technique	Actuarial model	[1]
Significant Unobservable Inputs Lapse rate			1.00%	[1]	30.00%	[1]
Significant Unobservable Inputs Annuitization rate			0.00%	[1]	50.00%	[1]

[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.