Segment Information Level 4 (Details) $ in Millions	3 Months Ended
Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Quarterly Financial Information, Segment Reporting, Change in Basis of Segmentation		3
Number of company reporting segments	6
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 378	$ 323
Net Income (Loss) Attributable to Parent	378	323
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	3,928	3,849
Insurance Commissions and Fees	455	445
Net Investment Income (Loss)	728	696
Total Realized Investment Gains (Losses)	(20)	(155)
Other Income	19	20
Revenues	4,655	4,410
Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	231	225
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	1,698	1,633
Insurance Commissions and Fees	10	10
Property and Casualty, Personal Insurance Product Line [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	33	23
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	945	984
Insurance Commissions and Fees	11	9
Affinity Earned Premiums	800	807
Property & Casualty Other Operations [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	24	17
Group Insurance Policies [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	45	50
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	835	795
Mutual Fund [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	23	20
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	191	167
Life and Annuity Insurance Product Line [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	68	17
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	258	269
Corporate Segment [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(46)	(29)
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Insurance Commissions and Fees	1	1
Non Proprietary [Member] \| Mutual Fund [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	167	142
Accident and Health Insurance Product Line [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	813	759
Accident and Health Insurance Product Line [Member] \| Group Insurance Policies [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	381	369
Package Business [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	314	308
Automobiles Commercial [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	161	158
Professional Liability [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	60	53
General Liability [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	148	143
Surety Product Line [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	55	53
Property Insurance Product Line [Member] \| Property and Casualty, Commercial Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	147	159
Automobiles Consumer [Member] \| Property and Casualty, Personal Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	662	685
Homeowners [Member] \| Property and Casualty, Personal Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	283	299
Life Insurance Product Line [Member] \| Group Insurance Policies [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	399	375
Property & Casualty Other Operations [Member] \| Group Insurance Policies [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	55	51
Proprietary [Member] \| Life and Annuity Insurance Product Line [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Earned premiums and fee income	$ 24	$ 25

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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