Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	$ 57,948	$ 62,440
Equity securities	5,082	4,104
Short-term investments	2,122	2,540
Other investments: Free-standing derivatives	1	2	$ 9
Separate account assets	3,658	4,396
Counterparty and cash collateral netting	$ (13)	$ (5)
Assets as a percent of assets measured at fair value	0.00%	0.00%
Mortgage loans		$ 6
Limited partnership interests	$ 42	3
Other Investments, Fair Value Disclosure	13
Other liabilities:
Other liabilities: Free-standing derivatives	(8)	(9)	$ (14)
Counterparty and cash collateral netting	$ 7	$ 22
Counterparty and cash collateral netting as a percent of liabilities measured at fair value	(2.20%)	(6.10%)
U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	$ 3,922	$ 4,328
Municipal
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	7,401	8,497
Foreign government
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1,033	1,645
RMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	947	1,207
CMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	466	615
Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	25	26
Quoted prices in active markets for identical assets (Level 1)
Assets
Total assets at fair value	$ 12,117	$ 12,117
Assets as a percent of assets measured at fair value	17.60%	16.50%
Other liabilities:
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	$ 55,781	$ 59,985
Assets as a percent of assets measured at fair value	80.90%	81.50%
Other liabilities:
Liabilities as a percent of liabilities measured at fair value	7.10%	13.80%
Significant unobservable inputs (Level 3)
Assets
Total assets at fair value	$ 1,036	$ 1,487
Assets as a percent of assets measured at fair value	1.50%	2.00%
Other liabilities:
Liabilities as a percent of liabilities measured at fair value	94.80%	92.00%
Recurring
Assets
Counterparty and cash collateral netting	$ (13)	$ (5)
Other liabilities:
Counterparty and cash collateral netting	7	22
Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	3,056	3,240
Equity securities	4,786	3,787
Short-term investments	615	692
Other investments: Free-standing derivatives	0	0
Separate account assets	3,658	4,396
Other assets	2	2
Total assets at fair value	12,117	12,117
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	0	0
Other liabilities:
Other liabilities: Free-standing derivatives	(1)	(1)
Total liabilities at fair value	(1)	(1)
Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	3,056	3,240
Recurring | Quoted prices in active markets for identical assets (Level 1) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate - public
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate - privately placed
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | ABS - CDO
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | ABS - consumer and other
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Significant other observable inputs (Level 2)
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	54,046	57,813
Equity securities	163	234
Short-term investments	1,507	1,843
Other investments: Free-standing derivatives	65	95
Separate account assets	0	0
Other assets	0	0
Total assets at fair value	55,781	59,985
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	0	0
Other liabilities:
Other liabilities: Free-standing derivatives	(23)	(50)
Total liabilities at fair value	(23)	(50)
Recurring | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	861	1,082
Recurring | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	7,240	8,227
Recurring | Significant other observable inputs (Level 2) | Corporate - public
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	30,356	31,340
Recurring | Significant other observable inputs (Level 2) | Corporate - privately placed
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	10,923	9,913
Recurring | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1,033	1,645
Recurring | Significant other observable inputs (Level 2) | ABS - CDO
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	716	1,044
Recurring | Significant other observable inputs (Level 2) | ABS - consumer and other
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1,500	2,738
Recurring | Significant other observable inputs (Level 2) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	946	1,206
Recurring | Significant other observable inputs (Level 2) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	446	592
Recurring | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	25	26
Recurring | Significant unobservable inputs (Level 3)
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	846	1,387
Equity securities	133	83
Short-term investments	0	5
Other investments: Free-standing derivatives	1	2
Separate account assets	0	0
Other assets	1	1
Total assets at fair value	981	1,478
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(299)	(323)
Other liabilities:
Other liabilities: Free-standing derivatives	(8)	(9)
Total liabilities at fair value	(307)	(332)
Recurring | Significant unobservable inputs (Level 3) | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	5	6
Recurring | Significant unobservable inputs (Level 3) | Municipal
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	161	270
Recurring | Significant unobservable inputs (Level 3) | Corporate - public
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	46	214
Recurring | Significant unobservable inputs (Level 3) | Corporate - privately placed
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	502	677
Recurring | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	0	0
Recurring | Significant unobservable inputs (Level 3) | ABS - CDO
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	61	104
Recurring | Significant unobservable inputs (Level 3) | ABS - consumer and other
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	50	92
Recurring | Significant unobservable inputs (Level 3) | RMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1	1
Recurring | Significant unobservable inputs (Level 3) | CMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	20	23
Recurring | Significant unobservable inputs (Level 3) | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	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	55	9
Fair value
Assets
Total assets at fair value	$ 68,921	$ 73,584
Assets as a percent of assets measured at fair value	100.00%	100.00%
Other liabilities:
Liabilities as a percent of liabilities measured at fair value	100.00%	100.00%
Fair value | Recurring
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	$ 57,948	$ 62,440
Equity securities	5,082	4,104
Short-term investments	2,122	2,540
Other investments: Free-standing derivatives	53	92
Separate account assets	3,658	4,396
Other assets	3	3
Total assets at fair value	68,866	73,575
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(299)	(323)
Other liabilities:
Other liabilities: Free-standing derivatives	(25)	(38)
Total liabilities at fair value	(324)	(361)
Fair value | Recurring | U.S. government and agencies
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	3,922	4,328
Fair value | Recurring | Municipal
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	7,401	8,497
Fair value | Recurring | Corporate - public
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	30,402	31,554
Fair value | Recurring | Corporate - privately placed
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	11,425	10,590
Fair value | Recurring | Foreign government
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1,033	1,645
Fair value | Recurring | ABS - CDO
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	777	1,148
Fair value | Recurring | ABS - consumer and other
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	1,550	2,830
Fair value | Recurring | RMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	947	1,207
Fair value | Recurring | CMBS
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	466	615
Fair value | Recurring | Redeemable preferred stock
Assets
Fixed income securities, at fair value (amortized cost $57,201 and $59,672)	25	26
Fair value | Non-recurring
Assets
Total assets at fair value	$ 55	$ 9