Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	$ 26,384	$ 28,117
Equity securities	923	970
Short-term investments	935	857
Other investments:
Free-standing derivatives, assets			$ 3
Separate account assets	4,120	4,396
Derivative asset, fair value, gross liability and obligation to return cash, offset	$ (9)	$ (2)
% of total assets at fair value	0.00%	0.00%
Other liabilities:
Free-standing derivatives, liabilities	$ (9)		$ (8)
Free standing derivative liabilities derivative liability, fair value, gross asset and right to reclaim cash, offset	$ 1	$ 2
% of total liabilities at fair value	(0.30%)	(0.60%)
U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	$ 755	$ 770
Municipal
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	3,489	3,662
Corporate
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	19,570	20,985
Foreign government
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	516	735
ABS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	971	765
RMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	531	605
CMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	536	579
Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	16	16
Quoted prices in active markets for identical assets (Level 1)
Other investments:
Total assets at fair value	$ 5,378	$ 5,561
% of total assets at fair value	16.60%	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	$ 26,229	$ 27,805
% of total assets at fair value	80.90%	80.70%
Other liabilities:
Total liabilities at fair value	$ (6)	$ (24)
% of total liabilities at fair value	1.80%	6.80%
Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	$ 827	$ 1,077
% of total assets at fair value	2.50%	3.10%
Other liabilities:
Total liabilities at fair value	$ (324)	$ (332)
% of total liabilities at fair value	98.50%	93.80%
Recurring basis
Other investments:
Free Standing Derivative Assets, Derivative Asset, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	$ (9)	$ (2)
Derivative asset, fair value, gross liability and obligation to return cash, offset	(9)	(2)
Other liabilities:
Free standing derivative liabilities derivative liability, fair value, gross asset and right to reclaim cash, offset	1	2
Recurring basis | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	321	147
Equity securities	870	927
Short-term investments	67	90
Other investments:
Free-standing derivatives, assets	0	0
Separate account assets	4,120	4,396
Other assets	0	1
Total assets at fair value	5,378	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, at fair value (amortized cost $24,767 and $25,822)	321	147
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | ABS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Significant other observable inputs (Level 2)
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	25,288	26,942
Equity securities	7	6
Short-term investments	868	767
Other investments:
Free-standing derivatives, assets	66	90
Separate account assets	0	0
Other assets	0	0
Total assets at fair value	26,229	27,805
Other liabilities:
Free-standing derivatives, liabilities	(6)	(24)
Recurring basis | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	434	623
Recurring basis | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	3,388	3,556
Recurring basis | Significant other observable inputs (Level 2) | Corporate
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	19,001	20,193
Recurring basis | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	516	735
Recurring basis | Significant other observable inputs (Level 2) | ABS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	866	636
Recurring basis | Significant other observable inputs (Level 2) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	531	605
Recurring basis | Significant other observable inputs (Level 2) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	536	578
Recurring basis | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	16	16
Recurring basis | Significant unobservable inputs (Level 3)
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	775	1,028
Equity securities	46	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	824	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, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	101	106
Recurring basis | Significant unobservable inputs (Level 3) | Corporate
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	569	792
Recurring basis | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Significant unobservable inputs (Level 3) | ABS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	105	129
Recurring basis | Significant unobservable inputs (Level 3) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Recurring basis | Significant unobservable inputs (Level 3) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	1
Recurring basis | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	0	0
Non-recurring basis
Other investments:
Derivative asset, fair value, gross liability and obligation to return cash, offset	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	3	9
Contractholder funds: 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
Contractholder funds: 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
Contractholder funds: Derivatives embedded in life and annuity contracts | Recurring basis | Significant unobservable inputs (Level 3)
Contract holder funds:
Derivatives embedded in life and annuity contracts	(315)	(323)
Fair value
Other investments:
Total assets at fair value	$ 32,425	$ 34,441
% of total assets at fair value	100.00%	100.00%
Mortgage loans		$ 6
Limited partnership interests	$ 3	3
Other liabilities:
Total liabilities at fair value	$ (329)	$ (354)
% of total liabilities at fair value	100.00%	100.00%
Fair value | Recurring basis
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	$ 26,384	$ 28,117
Equity securities	923	970
Short-term investments	935	857
Other investments:
Free-standing derivatives, assets	59	90
Separate account assets	4,120	4,396
Other assets	1	2
Total assets at fair value	32,422	34,432
Other liabilities:
Free-standing derivatives, liabilities	(14)	(31)
Fair value | Recurring basis | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	755	770
Fair value | Recurring basis | Municipal
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	3,489	3,662
Fair value | Recurring basis | Corporate
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	19,570	20,985
Fair value | Recurring basis | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	516	735
Fair value | Recurring basis | ABS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	971	765
Fair value | Recurring basis | RMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	531	605
Fair value | Recurring basis | CMBS
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	536	579
Fair value | Recurring basis | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $24,767 and $25,822)	16	16
Fair value | Non-recurring basis
Other investments:
Total assets at fair value	3	9
Fair value | Contractholder funds: Derivatives embedded in life and annuity contracts | Recurring basis
Contract holder funds:
Derivatives embedded in life and annuity contracts	$ (315)	$ (323)