Fair Values of Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Assets
Available-for-Sale securities: Fixed maturities	$ 25,368	$ 25,932
Common stocks	4	4
Separate account assets	72,532	69,395
Liabilities
Future policy benefits	29,979	30,670
Cumulative decrease to the embedded derivative liability	295	389
Recurring basis | Level 1
Assets
Available-for-Sale securities: Fixed maturities	10	10
Common stocks	2	2
Other assets	339	285
Total assets at fair value	351	297
Liabilities
Other liabilities	141	258
Total liabilities at fair value	141	258
Recurring basis | Level 1 | Equity derivative contracts
Assets
Other assets	339	285
Liabilities
Other liabilities	141	258
Recurring basis | Level 1 | U.S. government and agencies obligations
Assets
Available-for-Sale securities: Fixed maturities	10	10
Recurring basis | Level 2
Assets
Available-for-Sale securities: Fixed maturities	23,369	23,919
Common stocks	2	2
Cash equivalents	137	264
Other assets	2,811	3,133
Separate account assets	72,532	69,395
Total assets at fair value	98,851	96,713
Liabilities
Future policy benefits	64	47
Other liabilities	3,190	3,021
Total liabilities at fair value	3,254	3,068
Recurring basis | Level 2 | Interest rate derivative contracts
Assets
Other assets	1,937	2,191
Liabilities
Other liabilities	1,421	1,486
Recurring basis | Level 2 | Equity derivative contracts
Assets
Other assets	867	936
Liabilities
Other liabilities	1,768	1,535
Recurring basis | Level 2 | Foreign currency derivative contracts
Assets
Other assets	7	6
Liabilities
Other liabilities	1
Recurring basis | Level 2 | EIA embedded derivatives
Liabilities
Future policy benefits	3	2
Recurring basis | Level 2 | IUL embedded derivatives
Liabilities
Future policy benefits	61	45
Recurring basis | Level 2 | Corporate debt securities
Assets
Available-for-Sale securities: Fixed maturities	15,067	15,387
Recurring basis | Level 2 | Residential mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	3,569	3,598
Recurring basis | Level 2 | Commercial mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	2,657	2,834
Recurring basis | Level 2 | State and municipal obligations
Assets
Available-for-Sale securities: Fixed maturities	1,117	1,122
Recurring basis | Level 2 | Asset backed securities
Assets
Available-for-Sale securities: Fixed maturities	707	715
Recurring basis | Level 2 | Foreign government bonds and obligations
Assets
Available-for-Sale securities: Fixed maturities	214	224
Recurring basis | Level 2 | U.S. government and agencies obligations
Assets
Available-for-Sale securities: Fixed maturities	38	39
Recurring basis | Level 3
Assets
Available-for-Sale securities: Fixed maturities	1,989	2,003
Total assets at fair value	1,989	2,003
Liabilities
Future policy benefits	266	833
Total liabilities at fair value	266	833
Recurring basis | Level 3 | GMWB and GMAB embedded derivatives
Liabilities
Future policy benefits	266	833
Recurring basis | Level 3 | Corporate debt securities
Assets
Available-for-Sale securities: Fixed maturities	1,653	1,654
Recurring basis | Level 3 | Residential mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	8	23
Recurring basis | Level 3 | Commercial mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	168	170
Recurring basis | Level 3 | Asset backed securities
Assets
Available-for-Sale securities: Fixed maturities	160	156
Recurring basis | Total
Assets
Available-for-Sale securities: Fixed maturities	25,368	25,932
Common stocks	4	4
Cash equivalents	137	264
Other assets	3,150	3,418
Separate account assets	72,532	69,395
Total assets at fair value	101,191	99,013
Liabilities
Future policy benefits	330	880
Other liabilities	3,331	3,279
Total liabilities at fair value	3,661	4,159
Recurring basis | Total | Interest rate derivative contracts
Assets
Other assets	1,937	2,191
Liabilities
Other liabilities	1,421	1,486
Recurring basis | Total | Equity derivative contracts
Assets
Other assets	1,206	1,221
Liabilities
Other liabilities	1,909	1,793
Recurring basis | Total | Foreign currency derivative contracts
Assets
Other assets	7	6
Liabilities
Other liabilities	1
Recurring basis | Total | EIA embedded derivatives
Liabilities
Future policy benefits	3	2
Recurring basis | Total | IUL embedded derivatives
Liabilities
Future policy benefits	61	45
Recurring basis | Total | GMWB and GMAB embedded derivatives
Liabilities
Future policy benefits	266	833
Recurring basis | Total | Corporate debt securities
Assets
Available-for-Sale securities: Fixed maturities	16,720	17,041
Recurring basis | Total | Residential mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	3,577	3,621
Recurring basis | Total | Commercial mortgage backed securities
Assets
Available-for-Sale securities: Fixed maturities	2,825	3,004
Recurring basis | Total | State and municipal obligations
Assets
Available-for-Sale securities: Fixed maturities	1,117	1,122
Recurring basis | Total | Asset backed securities
Assets
Available-for-Sale securities: Fixed maturities	867	871
Recurring basis | Total | Foreign government bonds and obligations
Assets
Available-for-Sale securities: Fixed maturities	214	224
Recurring basis | Total | U.S. government and agencies obligations
Assets
Available-for-Sale securities: Fixed maturities	$ 48	$ 49