Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Assets
Fixed income securities:	$ 60,306	$ 57,948
Equity securities	5,288	5,082
Short-term investments	1,863	2,122
Other investments: Free-standing derivatives	1		$ 1
Separate account assets	3,469	3,658
Counterparty and cash collateral netting	$ (8)	$ (13)
% of total assets at fair value	0.00%	0.00%
Other liabilities:
Other liabilities: Free-standing derivatives	$ (4)		$ (9)
Counterparty and cash collateral netting	$ 22	$ 7
Counterparty and cash collateral netting as a percent of liabilities measured at fair value	(6.20%)	(2.20%)
U.S. government and agencies
Assets
Fixed income securities:	$ 4,304	$ 3,922
Municipal
Assets
Fixed income securities:	7,902	7,401
Foreign government
Assets
Fixed income securities:	1,119	1,033
Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	778	947
Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	315	466
Redeemable preferred stock
Assets
Fixed income securities:	24	25
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets at fair value	$ 12,194	$ 12,117
% of total assets at fair value	17.20%	17.60%
Other liabilities:
Total liabilities at fair value	$ (1)	$ (1)
Liabilities as a percent of liabilities measured at fair value	0.30%	0.30%
Significant other observable inputs (Level 2)
Assets
Total assets at fair value	$ 57,914	$ 55,781
% of total assets at fair value	81.50%	80.90%
Other liabilities:
Total liabilities at fair value	$ (66)	$ (23)
Liabilities as a percent of liabilities measured at fair value	18.50%	7.10%
Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	$ 938	$ 1,036
% of total assets at fair value	1.30%	1.50%
Other liabilities:
Total liabilities at fair value	$ (311)	$ (307)
Liabilities as a percent of liabilities measured at fair value	87.40%	94.80%
Fair Value, Measurements, Recurring [Member]
Assets
Other investments: Free-standing derivatives, Counterparty and cash collateral netting	$ (8)	$ (13)
Other liabilities:
Counterparty and cash collateral netting	22	7
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Fixed income securities:	3,440	3,056
Equity securities	4,941	4,786
Short-term investments	343	615
Other investments: Free-standing derivatives	0	0
Separate account assets	3,469	3,658
Other assets	1	2
Total assets at fair value	12,194	12,117
Other liabilities:
Other liabilities: Free-standing derivatives	(1)	(1)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government and agencies
Assets
Fixed income securities:	3,440	3,056
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate - public
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate - privately placed
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign government
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | ABS - CDO
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | ABS - consumer and other
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Redeemable preferred stock
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2)
Assets
Fixed income securities:	56,115	54,046
Equity securities	187	163
Short-term investments	1,520	1,507
Other investments: Free-standing derivatives	92	65
Separate account assets	0	0
Other assets	0	0
Total assets at fair value	57,914	55,781
Other liabilities:
Other liabilities: Free-standing derivatives	(66)	(23)
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities:	864	861
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities:	7,742	7,240
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Corporate - public
Assets
Fixed income securities:	31,789	30,356
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Corporate - privately placed
Assets
Fixed income securities:	12,271	10,923
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities:	1,119	1,033
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | ABS - CDO
Assets
Fixed income securities:	636	716
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | ABS - consumer and other
Assets
Fixed income securities:	601	1,500
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	777	946
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	292	446
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities:	24	25
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3)
Assets
Fixed income securities:	751	846
Equity securities	160	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	913	981
Other liabilities:
Other liabilities: Free-standing derivatives	(4)	(8)
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities:	0	5
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities:	160	161
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Corporate - public
Assets
Fixed income securities:	98	46
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Corporate - privately placed
Assets
Fixed income securities:	316	502
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities:	0	0
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | ABS - CDO
Assets
Fixed income securities:	74	61
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | ABS - consumer and other
Assets
Fixed income securities:	79	50
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	1	1
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	23	20
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities:	0	0
Non-recurring | Fair Value, Inputs, Level 1 [Member]
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	25	55
Derivatives embedded in life and annuity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	0	0
Derivatives embedded in life and annuity contracts | Fair Value, Measurements, Recurring [Member] | 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 | Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3)
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(307)	(299)
Fair value
Fair value of assets and liabilities measured on recurring and non-recurring basis
Limited partnership interests	16	42
Other investments	9	13
Assets
Total assets at fair value	$ 71,038	$ 68,921
% of total assets at fair value	100.00%	100.00%
Other liabilities:
Total liabilities at fair value	$ (356)	$ (324)
Liabilities as a percent of liabilities measured at fair value	100.00%	100.00%
Fair value | Fair Value, Measurements, Recurring [Member]
Assets
Fixed income securities:	$ 60,306	$ 57,948
Equity securities	5,288	5,082
Short-term investments	1,863	2,122
Other investments: Free-standing derivatives	85	53
Separate account assets	3,469	3,658
Other assets	2	3
Total assets at fair value	71,013	68,866
Other liabilities:
Other liabilities: Free-standing derivatives	(49)	(25)
Fair value | Fair Value, Measurements, Recurring [Member] | U.S. government and agencies
Assets
Fixed income securities:	4,304	3,922
Fair value | Fair Value, Measurements, Recurring [Member] | Municipal
Assets
Fixed income securities:	7,902	7,401
Fair value | Fair Value, Measurements, Recurring [Member] | Corporate - public
Assets
Fixed income securities:	31,887	30,402
Fair value | Fair Value, Measurements, Recurring [Member] | Corporate - privately placed
Assets
Fixed income securities:	12,587	11,425
Fair value | Fair Value, Measurements, Recurring [Member] | Foreign government
Assets
Fixed income securities:	1,119	1,033
Fair value | Fair Value, Measurements, Recurring [Member] | ABS - CDO
Assets
Fixed income securities:	710	777
Fair value | Fair Value, Measurements, Recurring [Member] | ABS - consumer and other
Assets
Fixed income securities:	680	1,550
Fair value | Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities (“RMBS”)
Assets
Fixed income securities:	778	947
Fair value | Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed securities (“CMBS”)
Assets
Fixed income securities:	315	466
Fair value | Fair Value, Measurements, Recurring [Member] | Redeemable preferred stock
Assets
Fixed income securities:	24	25
Fair value | Non-recurring
Assets
Total assets at fair value	25	55
Fair value | Derivatives embedded in life and annuity contracts | Fair Value, Measurements, Recurring [Member]
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(307)	(299)
Fixed Income Securities Valued Based on Nonbinding Broker Quotes
Assets
Total assets at fair value	311	625
Municipal Not Rated by Third Party Credit Rating Agencies
Assets
Total assets at fair value	$ 86	$ 96