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Percentage of earned premiums.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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The amount of estimated penalties recognized in the period arising from income tax examinations.

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The number of states the entity operates in as of the balance sheet date.

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Other investments not otherwise specified in the taxonomy.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Fair value amount of the specified investment category of assets maintained in separate accounts as of the balance sheet date.

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Summary Of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) state subsidiary independent_insurance_agency reporting_locations	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2008
Significant Accounting Policies
Income Tax Examination, Penalties Expense	$ 0
Number of operating subsidaries \| subsidiary	2
Number of independent insurance agencies \| independent_insurance_agency	1,526
Number of reporting locations \| reporting_locations	1,956
Number of states in which entity operates \| state	39
Defined Benefit Plan Qualifying Age				40 years
Current fair value of the BOLI invested assets and cash exceeded the current fair value of the contract holders' account value	$ 21,000,000
Other invested assets	67,000,000	$ 68,000,000
Depreciation expense	36,000,000	37,000,000	$ 37,000,000
Land, building and equipment impairments	$ 0	$ 0	$ 0
Minimum
Significant Accounting Policies
Estimated useful lives	3 years
Maximum
Significant Accounting Policies
Estimated useful lives	39 years 6 months
Life Policy Loans
Significant Accounting Policies
Other invested assets	$ 31,000,000
Venture Capital Funds
Significant Accounting Policies
Other invested assets	$ 36,000,000
10 Largest States
Significant Accounting Policies
Generated percentage of total earned premiums	62.00%	63.00%
Ohio, Largest State
Significant Accounting Policies
Generated percentage of total earned premiums	17.00%	18.00%
Indiana, Illinois, Pennsylvania, Georgia, Michigan and North Carolina \| Minimum
Significant Accounting Policies
Generated percentage of total earned premiums	5.00%
Indiana, Illinois, Pennsylvania, Georgia, Michigan and North Carolina \| Maximum
Significant Accounting Policies
Generated percentage of total earned premiums	7.00%
Largest Single Agency Relationship
Significant Accounting Policies
Generated percentage of total earned premiums	1.00%
All Other \| Maximum
Significant Accounting Policies
Generated percentage of total earned premiums	3.00%
Stock Options
Significant Accounting Policies
Awards vesting period	3 years
Weighted-average remaining contractual life for options expected to vest	10 years
Restricted Stock Units
Significant Accounting Policies
Awards vesting period	3 years
Property Casualty Insurance Segment
Significant Accounting Policies
Number of operating subsidaries \| subsidiary	2
Fixed Maturities
Significant Accounting Policies
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months and Below 70 Percent of Amortized Cost	5
Number of securities total unrealized loss in an unrealized loss position for 12 months or more	69	144	40