Fair Value Measurements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value Measurements Of Financial Instruments [Line Items]
Level 1 to Level 2 Transfers		$ 13
Level 2 to Level 1 Transfers	0	0
Guaranteed Living Benefits, Net Income Impact From Model Refinement	$ 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