Income Taxes Level 4 Deferred tax assets (liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Valuation Allowance, Commentary	The Company has recorded a deferred tax asset valuation allowance that is adequate to reduce the total deferred tax asset to an amount that will more likely than not be realized. In assessing the need for a valuation allowance, management considered future taxable temporary difference reversals, future taxable income exclusive of reversing temporary differences and carryovers, taxable income in open carry back years and other tax planning strategies. From time to time, tax planning strategies could include holding a portion of debt securities with market value losses until recovery, altering the level of tax exempt securities held, making investments which have specific tax characteristics, and business considerations such as asset-liability matching. Management views such tax planning strategies as prudent and feasible and would implement them, if necessary, to realize the deferred tax assets.
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Loss Reserves	$ 524	$ 573
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	162	163
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve	377	456
Deferred Tax Assets, Investments	831	1,020
Deferred Tax Assets, Derivative Instruments	90	44
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits	655	677
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	639	652
Deferred Tax Assets, Operating Loss Carryforwards	1,831	1,936
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	154	178
Deferred Tax Assets, Tax Credit Carryforwards		178
Deferred Tax Assets, Capital Loss Carryforwards	78	172
Deferred Tax Assets, Gross	5,341	5,871
Deferred Tax Assets, Valuation Allowance	(79)	(181)
Deferred Tax Assets, Net of Valuation Allowance	5,262	5,690
Tax Credit Carryforward, Valuation Allowance	1	9
Deferred Tax Assets, Tax Credit Carryforwards, Research	8
Deferred Tax Assets, Operating Loss Carryforwards, Foreign		8
Deferred Tax Assets, Operating Loss Carryforwards, Domestic		1,928
Components of Deferred Tax Liabilities [Abstract]
Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost	(943)	(1,040)
Tax Basis of Investments, Unrealized Appreciation (Depreciation), Net	(842)	(1,489)
Deferred Tax Liabilities, Deferred Expense	229	217
Deferred Tax Liabilities, Other	(42)	(47)
Deferred Tax Liabilities, Gross	2,056	2,793
Operating Loss Carryforwards, Valuation Allowance	78	172
Deferred Tax Assets, Net	3,206	2,897
Domestic Tax Authority [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards	1,814
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	5,182
Operating Loss Carryforwards		5,508
Foreign Tax Authority [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards	17
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	89
Operating Loss Carryforwards		39
Before Tax [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards	154
Deferred Tax Assets, Capital Loss Carryforwards	$ 222	$ 491
Earliest Tax Year [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2019
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2016
Expiring within Tax Years 2016 to 2017 [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 4
Latest Tax Year [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2024
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2033
Expiring within Tax Years 2018 to 2024 [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 154
Expiring within Tax Years 2023 to 2033 [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	5,178
Expiring Tax Year 2019 [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Capital Loss Carryforwards	222
No expiration tax year [Member]
Deferred Tax Assets, Net of Valuation Allowance [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	639
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 89