Investments (Details 23) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
The Components of Net Investment Income
Fixed maturity securities	$ 15,218	$ 15,037	$ 12,407
Equity securities	133	141	128
Trading securities - actively traded and FVO general account securities	88	31	73
Mortgage loans	3,191	3,164	2,824
Policy loans	626	641	649
Real estate and real estate joint ventures	834	688	372
Other limited partnership interests	845	681	879
Cash, cash equivalents and short-term investments	163	167	101
International joint ventures	19	(12)	(92)
Other	131	178	236
Subtotal	21,248	20,716	17,577
Less: Investment expenses	1,090	1,019	882
Subtotal, net	20,158	19,697	16,695
Trading securities - FVO contractholder-directed unit-linked investments	1,473	(453)	372
Securitized reverse residential mortgage loan	177	0	0
FVO consolidated securitization entities - changes in estimated fair value included in net investment gains (losses):
Commercial mortgage loans	172	332	411
Securities	4	9	15
Subtotal	1,826	(112)	798
Net investment income	21,984	19,585	17,493
Actively traded securities and FVO general account securities [Member]
Changes in estimated fair value subsequent to purchase included in net investment income:
Changes in estimated fair value included in net investment income	51	(3)	30
FVO contractholder-directed unit-linked investments [Member]
Changes in estimated fair value subsequent to purchase included in net investment income:
Changes in estimated fair value included in net investment income	$ 1,170	$ (647)	$ 322

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Securitized reverse residential mortgage loan.

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