Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Unbilled Audit Premiums	$ 9,000,000	$ 12,000,000	$ 7,000,000
Deposit contracts, liabilities	68,000,000us-gaap_DepositContractsLiabilities	72,000,000us-gaap_DepositContractsLiabilities
Depreciation	44,000,000us-gaap_Depreciation	38,000,000us-gaap_Depreciation	38,000,000us-gaap_Depreciation
Goodwill and intangible asset impairment	0
Indefinite-lived Intangible Assets [Line Items]
Interest payments	120,000,000us-gaap_InterestPaid	125,000,000us-gaap_InterestPaid	119,000,000us-gaap_InterestPaid
Income taxes paid	314,000,000us-gaap_IncomeTaxesPaid	186,000,000us-gaap_IncomeTaxesPaid	133,000,000us-gaap_IncomeTaxesPaid
Other Assets
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 96,000,000	$ 72,000,000

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Carrying amount of liabilities as of the balance sheet date pertaining to amounts received by the insurer or reinsurer from the insured (including a ceding company) under insurance or reinsurance contracts for which insurance risk is not transferred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 340

-SubTopic 30

-Section 50

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

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Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

+ References

No definition available.

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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The amount of cash paid for interest during the period.

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-Publisher FASB

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Increase (Decrease) In Earned Unbilled Audit Premiums

+ References

No definition available.

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