Derivative Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]
Loss after tax was reclassified from AOCI into Discontinued operations, net of income taxes			$ 4
Market-to-market losses after tax recognized on derivatives			2
Gains (losses) from changes in fair value of derivatives included in Investment gains (losses)		(1)	1	(4)
Losses from changes in fair value of derivatives held for trading included in Net investment income	(7)	(17)	(2)	(33)
Amount of gain (losses) recognized in OCI	(6)	1	2	(6)
Amount of gains (losses) reclassified from AOCI into income		(5)	3	(3)
Estimated amount of net unrealized losses associated with cash flow hedges that will be reclassified from AOCI into earnings during next twelve months			(6)
Maximum [Member]
Derivative [Line Items]
Net amounts recognized due to ineffectiveness	$ 1	$ 1	$ 1	$ 1