Reinsurance - Earned Life Insurance Premiums on Ceded Business (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	$ 958	$ 868	$ 1,893	$ 1,707
Assumed earned premiums	3	3	5	6
Ceded earned premiums	(51)	(45)	(99)	(89)
Life Insurance Segment
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	58	64	114	118
Assumed earned premiums	0	0	0	0
Ceded earned premiums	(14)	(13)	(28)	(26)
Net earned premiums	$ 44	$ 51	$ 86	$ 92