Fair Value of Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Fixed income securities	$ 77,017	$ 76,113
Equity securities	4,037	4,363
Short-term Investments	2,336	1,291
Other investments:
Free-standing derivatives, assets	3	1	74
Separate account assets	6,610	6,984
Other liabilities:
Free-standing derivatives, liabilities	(30)	(96)	(95)
U.S. government and agencies
Assets
Fixed income securities	4,713	6,315
Municipal
Assets
Fixed income securities	13,069	14,241
Corporate
Assets
Fixed income securities	48,537	43,581
Foreign government
Assets
Fixed income securities	2,517	2,081
Asset-backed securities ("ABS")
Assets
Fixed income securities	3,624	3,966
Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	3,032	4,121
Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,498	1,784
Redeemable preferred stock
Assets
Fixed income securities	27	24
Quoted prices in active markets for identical assets (Level 1)
Other investments:
Total assets at fair value	13,116	15,313
Assets as a percent of assets measured at fair value	14.60%	17.20%
Other liabilities:
Free-standing derivatives, liabilities		(1)
Total liabilities at fair value		(1)
Liabilities as a percent of liabilities measured at fair value		0.10%
Significant other observable inputs (Level 2)
Other investments:
Total assets at fair value	74,008	70,531
Assets as a percent of assets measured at fair value	82.10%	79.30%
Other liabilities:
Free-standing derivatives, liabilities	(98)	(112)
Total liabilities at fair value	(98)	(112)
Liabilities as a percent of liabilities measured at fair value	15.10%	13.10%
Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	3,081	3,226
Assets as a percent of assets measured at fair value	3.40%	3.60%
Contract holder funds:
Derivatives embedded in life and annuity contracts	(553)	(723)
Other liabilities:
Free-standing derivatives, liabilities	(30)	(96)
Total liabilities at fair value	(583)	(819)
Liabilities as a percent of liabilities measured at fair value	90.00%	95.80%
Counterparty and cash collateral netting
Other investments:
Total assets at fair value	(57)	(114)
Assets as a percent of assets measured at fair value	(0.10%)	(0.10%)
Other liabilities:
Free-standing derivatives, liabilities	33	77
Total liabilities at fair value	33	77
Liabilities as a percent of liabilities measured at fair value	(5.10%)	(9.00%)
Fair Value
Other investments:
Total assets at fair value	90,148	88,956
Assets as a percent of assets measured at fair value	100.00%	100.00%
Mortgage loans	4	19
Limited partnership interests	4
Other investments	1	16
Contract holder funds:
Derivatives embedded in life and annuity contracts	(553)	(723)
Other liabilities:
Free-standing derivatives, liabilities	(95)	(132)
Total liabilities at fair value	(648)	(855)
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	2,790	4,707
Equity securities	3,008	3,433
Short-term Investments	703	188
Other investments:
Separate account assets	6,610	6,984
Other assets	5	1
Total assets at fair value	13,116	15,313
Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities	2,790	4,707
Recurring | Significant other observable inputs (Level 2)
Assets
Fixed income securities	71,330	68,260
Equity securities	858	887
Short-term Investments	1,633	1,103
Other investments:
Free-standing derivatives, assets	187	281
Total assets at fair value	74,008	70,531
Recurring | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities	1,915	1,608
Recurring | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities	12,104	12,909
Recurring | Significant other observable inputs (Level 2) | Corporate
Assets
Fixed income securities	46,920	42,176
Recurring | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities	2,517	2,081
Recurring | Significant other observable inputs (Level 2) | Asset-backed securities ("ABS")
Assets
Fixed income securities	3,373	3,669
Recurring | Significant other observable inputs (Level 2) | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	3,029	4,070
Recurring | Significant other observable inputs (Level 2) | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,446	1,724
Recurring | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities	26	23
Recurring | Significant unobservable inputs (Level 3)
Assets
Fixed income securities	2,897	3,146
Equity securities	171	43
Other investments:
Free-standing derivatives, assets	3	1
Other assets	1	1
Total assets at fair value	3,072	3,191
Recurring | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities	8
Recurring | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities	965	1,332
Recurring | Significant unobservable inputs (Level 3) | Corporate
Assets
Fixed income securities	1,617	1,405
Recurring | Significant unobservable inputs (Level 3) | Asset-backed securities ("ABS")
Assets
Fixed income securities	251	297
Recurring | Significant unobservable inputs (Level 3) | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	3	51
Recurring | Significant unobservable inputs (Level 3) | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	52	60
Recurring | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities	1	1
Recurring | Counterparty and cash collateral netting
Other investments:
Free-standing derivatives, assets	(57)	(114)
Total assets at fair value	(57)	(114)
Recurring | Fair Value
Assets
Fixed income securities	77,017	76,113
Equity securities	4,037	4,363
Short-term Investments	2,336	1,291
Other investments:
Free-standing derivatives, assets	133	168
Separate account assets	6,610	6,984
Other assets	6	2
Total assets at fair value	90,139	88,921
Recurring | Fair Value | U.S. government and agencies
Assets
Fixed income securities	4,713	6,315
Recurring | Fair Value | Municipal
Assets
Fixed income securities	13,069	14,241
Recurring | Fair Value | Corporate
Assets
Fixed income securities	48,537	43,581
Recurring | Fair Value | Foreign government
Assets
Fixed income securities	2,517	2,081
Recurring | Fair Value | Asset-backed securities ("ABS")
Assets
Fixed income securities	3,624	3,966
Recurring | Fair Value | Residential mortgage-backed securities ("RMBS")
Assets
Fixed income securities	3,032	4,121
Recurring | Fair Value | Commercial mortgage-backed securities ("CMBS")
Assets
Fixed income securities	1,498	1,784
Recurring | Fair Value | Redeemable preferred stock
Assets
Fixed income securities	27	24
Non-recurring | Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	9	35
Non-recurring | Fair Value
Other investments:
Total assets at fair value	$ 9	$ 35