Fair Value Measurements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Year	Jun. 30, 2012	Jun. 30, 2013 Year	Jun. 30, 2012
Fair Value Measurements Of Financial Instruments [Line Items]
GLB - Lapse rate - lower range	1.00%		1.00%
GLB - Lapse rate - upper range	6.00%		6.00%
GLB - Spike lapse rate - lower range	10.00%		10.00%
GLB - Spike lapse rate - upper range	30.00%		30.00%
GLB - Ultimate lapse rate	10.00%		10.00%
GLB - Length of ultimate lapse rate period, years	2		2
GLB - Adjustment factor for valuable guarantees - lower	15.00%		15.00%
GLB - Adjustment factor for valuable guarantees - upper	75.00%		75.00%
Percent of GMIB guaranteed value that are represented by clients with several years of annuitization experience	37.00%		37.00%
GLB - Maximum annuitization rate	8.00%		8.00%
GLB - First year maximum annuitization rate	13.00%		13.00%
GLB - Weighted average maximum annuitization rate - rate 1	8.00%		8.00%
GLB - Weighted average maximum annuitization rate - rate 2	12.00%		12.00%
GLB - Weighted average maximum annuitization rate - rate 3	30.00%		30.00%
Level 1 to Level 2 Transfers	$ 6	$ 1	$ 19	$ 6
Level 2 to Level 1 Transfers	$ 0	$ 0	$ 0	$ 0
Guaranteed Living Benefits Number Of Annuitization Functions	3		3
Redemption Notice Periods Lower Range [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice period for redemption for alternative investments investment funds, days			5 days
Redemption Notice Periods Upper Range [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice period for redemption for alternative investments investment funds, days			120 days