Investments (Details 26) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
The Components of Net Investment Income
Fixed maturity securities	$ 15,037	$ 12,407	$ 11,545
Equity securities	141	128	178
Trading securities - actively traded and FVO general account securities	31	73	116
Mortgage loans	3,164	2,824	2,741
Policy loans	641	649	641
Real estate and real estate joint ventures	704	391	(245)
Other limited partnership interests	681	879	174
Cash, cash equivalents and short-term investments	167	101	128
International joint ventures	3	(81)	(115)
Other	178	236	205
Subtotal	20,747	17,607	15,368
Less: Investment expenses	1,029	894	911
Subtotal, net	19,718	16,713	14,457
Trading securities - FVO contractholder-directed unit-linked investments	(453)	372	284
FVO consolidated securitization entities:
Commercial mortgage loans	332	411	0
Securities	9	15	0
Subtotal	(112)	798	284
Net investment income	19,606	17,511	14,741
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	(3)	30	34
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	$ (647)	$ 322	$ 275

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