Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Assets
Fixed income securities:	$ 57,291	$ 57,948
Equity securities	5,117	5,082
Short-term investments	3,526	2,122
Other investments: Free-standing derivatives	1		$ 2
Separate account assets	3,507	3,658
Counterparty and cash collateral netting	$ (15)	$ (13)
% of total assets at fair value	0.00%	0.00%
Other liabilities:
Other liabilities: Free-standing derivatives	$ (9)		$ (9)
Counterparty and cash collateral netting	$ 16	$ 7
Counterparty and cash collateral netting as a percent of liabilities measured at fair value	(4.70%)	(2.20%)
U.S. government and agencies
Assets
Fixed income securities:	$ 3,504	$ 3,922
Municipal
Assets
Fixed income securities:	7,616	7,401
Foreign government
Assets
Fixed income securities:	1,054	1,033
Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	875	947
Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	447	466
Redeemable preferred stock
Assets
Fixed income securities:	24	25
Quoted prices in active markets for identical assets (Level 1)
Assets
Total assets at fair value	$ 11,755	$ 12,117
% of total assets at fair value	16.90%	17.60%
Other liabilities:
Total liabilities at fair value	$ 0	$ (1)
Liabilities as a percent of liabilities measured at fair value	0.00%	0.30%
Significant other observable inputs (Level 2)
Assets
Total assets at fair value	$ 56,748	$ 55,781
% of total assets at fair value	81.60%	80.90%
Other liabilities:
Total liabilities at fair value	$ (36)	$ (23)
Liabilities as a percent of liabilities measured at fair value	10.50%	7.10%
Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	$ 1,050	$ 1,036
% of total assets at fair value	1.50%	1.50%
Other liabilities:
Total liabilities at fair value	$ (322)	$ (307)
Liabilities as a percent of liabilities measured at fair value	94.20%	94.80%
Recurring
Assets
Other investments: Free-standing derivatives, Counterparty and cash collateral netting	$ (15)	$ (13)
Other liabilities:
Counterparty and cash collateral netting	16	7
Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities:	2,641	3,056
Equity securities	4,821	4,786
Short-term investments	786	615
Other investments: Free-standing derivatives	0	0
Separate account assets	3,507	3,658
Other assets	0	2
Total assets at fair value	11,755	12,117
Other liabilities:
Other liabilities: Free-standing derivatives	0	(1)
Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities:	2,641	3,056
Recurring | Quoted prices in active markets for identical assets (Level 1) | Municipal
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate - public
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate - privately placed
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Foreign government
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | ABS - CDO
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | ABS - consumer and other
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Redeemable preferred stock
Assets
Fixed income securities:	0	0
Recurring | Significant other observable inputs (Level 2)
Assets
Fixed income securities:	53,765	54,046
Equity securities	171	163
Short-term investments	2,740	1,507
Other investments: Free-standing derivatives	72	65
Separate account assets	0	0
Other assets	0	0
Total assets at fair value	56,748	55,781
Other liabilities:
Other liabilities: Free-standing derivatives	(36)	(23)
Recurring | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities:	859	861
Recurring | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities:	7,470	7,240
Recurring | Significant other observable inputs (Level 2) | Corporate - public
Assets
Fixed income securities:	30,081	30,356
Recurring | Significant other observable inputs (Level 2) | Corporate - privately placed
Assets
Fixed income securities:	10,579	10,923
Recurring | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities:	1,054	1,033
Recurring | Significant other observable inputs (Level 2) | ABS - CDO
Assets
Fixed income securities:	687	716
Recurring | Significant other observable inputs (Level 2) | ABS - consumer and other
Assets
Fixed income securities:	1,710	1,500
Recurring | Significant other observable inputs (Level 2) | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	874	946
Recurring | Significant other observable inputs (Level 2) | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	427	446
Recurring | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities:	24	25
Recurring | Significant unobservable inputs (Level 3)
Assets
Fixed income securities:	885	846
Equity securities	125	133
Short-term investments	0	0
Other investments: Free-standing derivatives	1	1
Separate account assets	0	0
Other assets	1	1
Total assets at fair value	1,012	981
Other liabilities:
Other liabilities: Free-standing derivatives	(9)	(8)
Recurring | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities:	4	5
Recurring | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities:	146	161
Recurring | Significant unobservable inputs (Level 3) | Corporate - public
Assets
Fixed income securities:	63	46
Recurring | Significant unobservable inputs (Level 3) | Corporate - privately placed
Assets
Fixed income securities:	549	502
Recurring | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities:	0	0
Recurring | Significant unobservable inputs (Level 3) | ABS - CDO
Assets
Fixed income securities:	58	61
Recurring | Significant unobservable inputs (Level 3) | ABS - consumer and other
Assets
Fixed income securities:	44	50
Recurring | Significant unobservable inputs (Level 3) | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	1	1
Recurring | Significant unobservable inputs (Level 3) | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	20	20
Recurring | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities:	0	0
Non-recurring | Quoted prices in active markets for identical assets (Level 1)
Assets
Total assets at fair value	0	0
Non-recurring | Significant other observable inputs (Level 2)
Assets
Total assets at fair value	0	0
Non-recurring | Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	38	55
Derivatives embedded in life and annuity contracts | Recurring | Quoted prices in active markets for identical assets (Level 1)
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	0	0
Derivatives embedded in life and annuity contracts | Recurring | Significant other observable inputs (Level 2)
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	0	0
Derivatives embedded in life and annuity contracts | Recurring | Significant unobservable inputs (Level 3)
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(313)	(299)
Fair value
Fair value of assets and liabilities measured on recurring and non-recurring basis
Limited partnership interests	27	42
Other investments	11	13
Assets
Total assets at fair value	$ 69,538	$ 68,921
% of total assets at fair value	100.00%	100.00%
Other liabilities:
Total liabilities at fair value	$ (342)	$ (324)
Liabilities as a percent of liabilities measured at fair value	100.00%	100.00%
Fair value | Recurring
Assets
Fixed income securities:	$ 57,291	$ 57,948
Equity securities	5,117	5,082
Short-term investments	3,526	2,122
Other investments: Free-standing derivatives	58	53
Separate account assets	3,507	3,658
Other assets	1	3
Total assets at fair value	69,500	68,866
Other liabilities:
Other liabilities: Free-standing derivatives	(29)	(25)
Fair value | Recurring | U.S. government and agencies
Assets
Fixed income securities:	3,504	3,922
Fair value | Recurring | Municipal
Assets
Fixed income securities:	7,616	7,401
Fair value | Recurring | Corporate - public
Assets
Fixed income securities:	30,144	30,402
Fair value | Recurring | Corporate - privately placed
Assets
Fixed income securities:	11,128	11,425
Fair value | Recurring | Foreign government
Assets
Fixed income securities:	1,054	1,033
Fair value | Recurring | ABS - CDO
Assets
Fixed income securities:	745	777
Fair value | Recurring | ABS - consumer and other
Assets
Fixed income securities:	1,754	1,550
Fair value | Recurring | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	875	947
Fair value | Recurring | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	447	466
Fair value | Recurring | Redeemable preferred stock
Assets
Fixed income securities:	24	25
Fair value | Non-recurring
Assets
Total assets at fair value	38	55
Fair value | Derivatives embedded in life and annuity contracts | Recurring
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(313)	(299)
Fixed income securities - non-binding broker quotes
Assets
Total assets at fair value	616	625
Municipal - not rated by third party credit rating agencies
Assets
Total assets at fair value	$ 85	$ 96