Fair Value of Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Assets
Fixed income securities	$ 27,802	$ 28,117
Equity securities	1,032	970
Short-term Investments	820	857
Other investments:
Free-standing derivatives, assets			5
Separate account assets	4,303	4,396
Derivative asset, fair value, gross liability and obligation to return cash, offset	(6)	(2)
% of total assets at fair value	0.00%	0.00%
Contract holder funds:
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	(326)	(323)	(549)	(553)
Other liabilities:
Free-standing derivatives, liabilities	(9)		(12)
Free standing derivative liabilities derivative liability, fair value, gross asset and right to reclaim cash, offset	2	2
% of total liabilities at fair value	(0.60%)	(0.60%)
U.S. government and agencies
Assets
Fixed income securities	639	770
Municipal
Assets
Fixed income securities	3,662	3,662
Corporate
Assets
Fixed income securities	20,749	20,985
Foreign government
Assets
Fixed income securities	562	735
ABS
Assets
Fixed income securities	1,043	765
RMBS
Assets
Fixed income securities	573	605
CMBS
Assets
Fixed income securities	558	579
Redeemable preferred stock
Assets
Fixed income securities	16	16
Quoted prices in active markets for identical assets (Level 1)
Other investments:
Total assets at fair value	5,490	5,561
% of total assets at fair value	16.10%	16.20%
Other liabilities:
Total liabilities at fair value	0	0
% of total liabilities at fair value	0.00%	0.00%
Significant other observable inputs (Level 2)
Other investments:
Total assets at fair value	27,554	27,805
% of total assets at fair value	80.90%	80.70%
Other liabilities:
Total liabilities at fair value	(12)	(24)
% of total liabilities at fair value	3.50%	6.80%
Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	1,003	1,077
% of total assets at fair value	3.00%	3.10%
Other liabilities:
Total liabilities at fair value	(335)	(332)
% of total liabilities at fair value	97.10%	93.80%
Recurring basis
Other investments:
Free Standing Derivative Assets, Derivative Asset, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	6
Derivative asset, fair value, gross liability and obligation to return cash, offset	(6)	(2)
Other liabilities:
Free standing derivative liabilities derivative liability, fair value, gross asset and right to reclaim cash, offset	2	2
Recurring basis | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities	137	147
Equity securities	986	927
Short-term Investments	63	90
Other investments:
Free-standing derivatives, assets	0	0
Separate account assets	4,303	4,396
Other assets	1	1
Total assets at fair value	5,490	5,561
Other liabilities:
Free-standing derivatives, liabilities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities	137	147
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Municipal
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Foreign government
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | ABS
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | RMBS
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | CMBS
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Redeemable preferred stock
Assets
Fixed income securities	0	0
Recurring basis | Significant other observable inputs (Level 2)
Assets
Fixed income securities	26,709	26,942
Equity securities	7	6
Short-term Investments	757	767
Other investments:
Free-standing derivatives, assets	81	90
Separate account assets	0	0
Other assets	0	0
Total assets at fair value	27,554	27,805
Other liabilities:
Free-standing derivatives, liabilities	(12)	(24)
Recurring basis | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities	502	623
Recurring basis | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities	3,556	3,556
Recurring basis | Significant other observable inputs (Level 2) | Corporate
Assets
Fixed income securities	20,010	20,193
Recurring basis | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities	562	735
Recurring basis | Significant other observable inputs (Level 2) | ABS
Assets
Fixed income securities	932	636
Recurring basis | Significant other observable inputs (Level 2) | RMBS
Assets
Fixed income securities	573	605
Recurring basis | Significant other observable inputs (Level 2) | CMBS
Assets
Fixed income securities	558	578
Recurring basis | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities	16	16
Recurring basis | Significant unobservable inputs (Level 3)
Assets
Fixed income securities	956	1,028
Equity securities	39	37
Short-term Investments	0	0
Other investments:
Free-standing derivatives, assets	2	2
Separate account assets	0	0
Other assets	1	1
Total assets at fair value	998	1,068
Other liabilities:
Free-standing derivatives, liabilities	(9)	(9)
Recurring basis | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities	0	0
Recurring basis | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities	106	106
Recurring basis | Significant unobservable inputs (Level 3) | Corporate
Assets
Fixed income securities	739	792
Recurring basis | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities	0	0
Recurring basis | Significant unobservable inputs (Level 3) | ABS
Assets
Fixed income securities	111	129
Recurring basis | Significant unobservable inputs (Level 3) | RMBS
Assets
Fixed income securities	0	0
Recurring basis | Significant unobservable inputs (Level 3) | CMBS
Assets
Fixed income securities	0	1
Recurring basis | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities	0	0
Non-recurring basis | Quoted prices in active markets for identical assets (Level 1)
Other investments:
Total assets at fair value	0	0
Non-recurring basis | Significant other observable inputs (Level 2)
Other investments:
Total assets at fair value	0	0
Non-recurring basis | Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	5	9
Derivatives embedded in life and annuity contracts
Contract holder funds:
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	(326)	(323)	(319)	(307)
Derivatives embedded in life and annuity contracts | Recurring basis | Quoted prices in active markets for identical assets (Level 1)
Contract holder funds:
Derivatives embedded in life and annuity contracts	0	0
Derivatives embedded in life and annuity contracts | Recurring basis | Significant other observable inputs (Level 2)
Contract holder funds:
Derivatives embedded in life and annuity contracts	0	0
Derivatives embedded in life and annuity contracts | Recurring basis | Significant unobservable inputs (Level 3)
Contract holder funds:
Derivatives embedded in life and annuity contracts	(326)
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		(323)
Fair Value
Other investments:
Total assets at fair value	34,041	34,441
% of total assets at fair value	100.00%	100.00%
Mortgage loans		6
Limited partnership interests	5	3
Other liabilities:
Total liabilities at fair value	(345)	(354)
% of total liabilities at fair value	100.00%	100.00%
Fair Value | Recurring basis
Assets
Fixed income securities	27,802	28,117
Equity securities	1,032	970
Short-term Investments	820	857
Other investments:
Free-standing derivatives, assets	77	90
Separate account assets	4,303	4,396
Other assets	2	2
Total assets at fair value	34,036	34,432
Other liabilities:
Free-standing derivatives, liabilities	(19)	(31)
Fair Value | Recurring basis | U.S. government and agencies
Assets
Fixed income securities	639	770
Fair Value | Recurring basis | Municipal
Assets
Fixed income securities	3,662	3,662
Fair Value | Recurring basis | Corporate
Assets
Fixed income securities	20,749	20,985
Fair Value | Recurring basis | Foreign government
Assets
Fixed income securities	562	735
Fair Value | Recurring basis | ABS
Assets
Fixed income securities	1,043	765
Fair Value | Recurring basis | RMBS
Assets
Fixed income securities	573	605
Fair Value | Recurring basis | CMBS
Assets
Fixed income securities	558	579
Fair Value | Recurring basis | Redeemable preferred stock
Assets
Fixed income securities	16	16
Fair Value | Non-recurring basis
Other investments:
Total assets at fair value	5	9
Fair Value | Derivatives embedded in life and annuity contracts | Recurring basis
Contract holder funds:
Derivatives embedded in life and annuity contracts	$ (326)	$ (323)