Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) (Guaranteed Minimum Income Benefit [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	$ 1,354	[1]
Valuation Technique	Actuarial model	[1]
Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	1.00%
Significant Unobservable Inputs Annuitization rate	0.00%
Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	30.00%
Significant Unobservable Inputs Annuitization rate	50.00%

[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 5 Guaranteed living benefits.