Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fixed income securities	$ 24,629	$ 28,117
Equity securities	1,542	970
Short-term investments	816	857
Other investments:
Other investments: Free-standing derivatives	1	2	$ 9
Separate account assets	3,639	4,396
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	$ (11)	$ (2)
% of total assets at fair value	0.00%	0.00%
Other Investments, Fair Value Disclosure	$ 5
Other liabilities:
Other liabilities: Free-standing derivatives	$ (8)	$ (9)	$ (14)
% of total liabilities at fair value	(0.30%)	(0.60%)
U.S. government and agencies
Assets
Fixed income securities	$ 977	$ 770
Municipal
Assets
Fixed income securities	2,442	3,662
Foreign government
Assets
Fixed income securities	384	735
RMBS
Assets
Fixed income securities	451	605
CMBS
Assets
Fixed income securities	436	579
Redeemable preferred stock
Assets
Fixed income securities	15	16
Quoted prices in active markets for identical assets (Level 1)
Other investments:
Total assets at fair value	$ 5,858	$ 5,561
% of total assets at fair value	19.10%	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	$ 24,102	$ 27,805
% of total assets at fair value	78.50%	80.70%
Other liabilities:
Total liabilities at fair value	$ (7)	$ (24)
% of total liabilities at fair value	2.20%	6.80%
Significant unobservable inputs (Level 3)
Other investments:
Total assets at fair value	$ 736	$ 1,077
% of total assets at fair value	2.40%	3.10%
Other liabilities:
Total liabilities at fair value	$ (307)	$ (332)
% of total liabilities at fair value	98.10%	93.80%
Recurring basis
Other investments:
Counterparty and cash collateral netting	$ (11)	$ (2)
Separate account assets		0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(11)	(2)
Other liabilities:
Counterparty and cash collateral netting	1	2
Derivative Liability Counterparty Netting and Collateral Right To Reclaim Cash Offset	1	2
Recurring basis | Quoted prices in active markets for identical assets (Level 1)
Assets
Fixed income securities	546	147
Equity securities	1,479	927
Short-term investments	193	90
Other investments:
Other investments: Free-standing derivatives	0	0
Separate account assets	3,639	4,396
Other assets	1	1
Total assets at fair value	5,858	5,561
Other liabilities:
Other liabilities: Free-standing derivatives	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies
Assets
Fixed income securities	546	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 - public
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate - privately placed
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 - CDO
Assets
Fixed income securities	0	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | ABS - consumer and other
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	23,417	26,942
Equity securities	3	6
Short-term investments	623	767
Other investments:
Other investments: Free-standing derivatives	59	90
Separate account assets	0
Other assets	0	0
Total assets at fair value	24,102	27,805
Other liabilities:
Other liabilities: Free-standing derivatives	(7)	(24)
Recurring basis | Significant other observable inputs (Level 2) | U.S. government and agencies
Assets
Fixed income securities	431	623
Recurring basis | Significant other observable inputs (Level 2) | Municipal
Assets
Fixed income securities	2,364	3,556
Recurring basis | Significant other observable inputs (Level 2) | Corporate - public
Assets
Fixed income securities	12,490	14,519
Recurring basis | Significant other observable inputs (Level 2) | Corporate - privately placed
Assets
Fixed income securities	5,523	5,674
Recurring basis | Significant other observable inputs (Level 2) | Foreign government
Assets
Fixed income securities	384	735
Recurring basis | Significant other observable inputs (Level 2) | ABS - CDO
Assets
Fixed income securities	178	323
Recurring basis | Significant other observable inputs (Level 2) | ABS - consumer and other
Assets
Fixed income securities	1,145	313
Recurring basis | Significant other observable inputs (Level 2) | RMBS
Assets
Fixed income securities	451	605
Recurring basis | Significant other observable inputs (Level 2) | CMBS
Assets
Fixed income securities	436	578
Recurring basis | Significant other observable inputs (Level 2) | Redeemable preferred stock
Assets
Fixed income securities	15	16
Recurring basis | Significant unobservable inputs (Level 3)
Assets
Fixed income securities	666	1,028
Equity securities	60	37
Short-term investments	0	0
Other investments:
Other investments: Free-standing derivatives	1	2
Separate account assets	0	0
Other assets	1	1
Total assets at fair value	728	1,068
Other liabilities:
Other liabilities: Free-standing derivatives	(8)	(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	78	106
Recurring basis | Significant unobservable inputs (Level 3) | Corporate - public
Assets
Fixed income securities	44	160
Recurring basis | Significant unobservable inputs (Level 3) | Corporate - privately placed
Assets
Fixed income securities	447	632
Recurring basis | Significant unobservable inputs (Level 3) | Foreign government
Assets
Fixed income securities	0	0
Recurring basis | Significant unobservable inputs (Level 3) | ABS - CDO
Assets
Fixed income securities	53	67
Recurring basis | Significant unobservable inputs (Level 3) | ABS - consumer and other
Assets
Fixed income securities	44	62
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
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	8	9
Fair value
Other investments:
Total assets at fair value	$ 30,685	$ 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	$ (313)	$ (354)
% of total liabilities at fair value	100.00%	100.00%
Fair value | Recurring basis
Assets
Fixed income securities	$ 24,629	$ 28,117
Equity securities	1,542	970
Short-term investments	816	857
Other investments:
Other investments: Free-standing derivatives	49	90
Separate account assets	3,639	4,396
Other assets	2	2
Total assets at fair value	30,677	34,432
Contract holder funds:
Contractholder funds: Derivatives embedded in life and annuity contracts	(299)	(323)
Other liabilities:
Other liabilities: Free-standing derivatives	(14)	(31)
Fair value | Recurring basis | Corporate - public
Assets
Fixed income securities	12,534	14,679
Fair value | Recurring basis | Corporate - privately placed
Assets
Fixed income securities	5,970	6,306
Fair value | Recurring basis | Foreign government
Assets
Fixed income securities	384	735
Fair value | Recurring basis | ABS - CDO
Assets
Fixed income securities	231	390
Fair value | Recurring basis | ABS - consumer and other
Assets
Fixed income securities	1,189	375
Fair value | Recurring basis | RMBS
Assets
Fixed income securities	451	605
Fair value | Recurring basis | CMBS
Assets
Fixed income securities	436	579
Fair value | Non-recurring basis
Other investments:
Total assets at fair value	8	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:
Contractholder 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:
Contractholder 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:
Contractholder funds: Derivatives embedded in life and annuity contracts	$ (299)	$ (323)