Fair Value of Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Assets
Fixed income securities	$ 71,039	$ 77,017
Equity securities	4,505	4,037
Short-term Investments	2,646	2,336
Free-standing derivatives, assets	6		1
Separate account assets	6,488	6,610
Other liabilities:
Free-standing derivatives, liabilities	(13)		(72)
U.S. government and agencies
Assets
Fixed income securities	3,204	4,713
Municipal
Assets
Fixed income securities	10,716	13,069
Corporate
Assets
Fixed income securities	47,616	48,537
Foreign government
Assets
Fixed income securities	2,224	2,517
Asset-backed securities ("ABS")
Assets
Fixed income securities	3,476	3,624
Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	2,485	3,032
Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,291	1,498
Redeemable preferred stock
Assets
Fixed income securities	27	27
Quoted prices in active markets for identical assets (Level 1)
Assets
Total assets at fair value	12,345	13,116
Assets as a percent of assets measured at fair value	14.50%	14.60%
Significant other observable inputs (Level 2)
Assets
Total assets at fair value	70,145	74,008
Assets as a percent of assets measured at fair value	82.60%	82.10%
Other liabilities:
Free-standing derivatives, liabilities	(140)	(98)
Total liabilities at fair value	(140)	(98)
Liabilities as a percent of liabilities measured at fair value	20.80%	15.10%
Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	2,485	3,081
Assets as a percent of assets measured at fair value	2.90%	3.40%
Contract holder funds:
Derivatives embedded in life and annuity contracts	(533)	(553)
Other liabilities:
Free-standing derivatives, liabilities	(13)	(30)
Total liabilities at fair value	(546)	(583)
Liabilities as a percent of liabilities measured at fair value	81.00%	90.00%
Counterparty and cash collateral netting
Assets
Total assets at fair value	(17)	(57)
Assets as a percent of assets measured at fair value		(0.10%)
Other liabilities:
Free-standing derivatives, liabilities	12	33
Total liabilities at fair value	12	33
Liabilities as a percent of liabilities measured at fair value	(1.80%)	(5.10%)
Fair Value
Assets
Total assets at fair value	84,958	90,148
Assets as a percent of assets measured at fair value	100.00%	100.00%
Mortgage loans	51	4
Limited partnership interests	26	4
Other investments		1
Contract holder funds:
Derivatives embedded in life and annuity contracts	(533)	(553)
Other liabilities:
Free-standing derivatives, liabilities	(141)	(95)
Total liabilities at fair value	(674)	(648)
Liabilities as a percent of liabilities measured at fair value	100.00%	100.00%
Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities	1,793	2,790
Equity securities	3,463	3,008
Short-term Investments	599	703
Separate account assets	6,488	6,610
Other assets	2	5
Total assets at fair value	12,345	13,116
Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities	1,793	2,790
Recurring | Significant other observable inputs (Level 2)
Assets
Fixed income securities	66,970	71,330
Equity securities	917	858
Short-term Investments	2,047	1,633
Free-standing derivatives, assets	211	187
Total assets at fair value	70,145	74,008
Recurring | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities	1,404	1,915
Recurring | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities	10,163	12,104
Recurring | Significant other observable inputs (Level 2) | Corporate
Assets
Fixed income securities	46,233	46,920
Recurring | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities	2,224	2,517
Recurring | Significant other observable inputs (Level 2) | Asset-backed securities ("ABS")
Assets
Fixed income securities	3,188	3,373
Recurring | Significant other observable inputs (Level 2) | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	2,482	3,029
Recurring | Significant other observable inputs (Level 2) | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,250	1,446
Recurring | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities	26	26
Recurring | Significant unobservable inputs (Level 3)
Assets
Fixed income securities	2,276	2,897
Equity securities	125	171
Free-standing derivatives, assets	6	3
Other assets	1	1
Total assets at fair value	2,408	3,072
Recurring | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities	7	8
Recurring | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities	553	965
Recurring | Significant unobservable inputs (Level 3) | Corporate
Assets
Fixed income securities	1,383	1,617
Recurring | Significant unobservable inputs (Level 3) | Asset-backed securities ("ABS")
Assets
Fixed income securities	288	251
Recurring | Significant unobservable inputs (Level 3) | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	3	3
Recurring | Significant unobservable inputs (Level 3) | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	41	52
Recurring | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities	1	1
Recurring | Counterparty and cash collateral netting
Assets
Free-standing derivatives, assets	(17)	(57)
Total assets at fair value	(17)	(57)
Recurring | Fair Value
Assets
Fixed income securities	71,039	77,017
Equity securities	4,505	4,037
Short-term Investments	2,646	2,336
Free-standing derivatives, assets	200	133
Separate account assets	6,488	6,610
Other assets	3	6
Total assets at fair value	84,881	90,139
Recurring | Fair Value | U.S. government and agencies
Assets
Fixed income securities	3,204	4,713
Recurring | Fair Value | Municipal
Assets
Fixed income securities	10,716	13,069
Recurring | Fair Value | Corporate
Assets
Fixed income securities	47,616	48,537
Recurring | Fair Value | Foreign government
Assets
Fixed income securities	2,224	2,517
Recurring | Fair Value | Asset-backed securities ("ABS")
Assets
Fixed income securities	3,476	3,624
Recurring | Fair Value | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	2,485	3,032
Recurring | Fair Value | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,291	1,498
Recurring | Fair Value | Redeemable preferred stock
Assets
Fixed income securities	27	27
Non-recurring | Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	77	9
Non-recurring | Fair Value
Assets
Total assets at fair value	$ 77	$ 9