Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill, beginning of year	$ 268,376us-gaap_Goodwill	$ 268,376us-gaap_Goodwill
Additions	9,882us-gaap_GoodwillAcquiredDuringPeriod
Goodwill, end of year	278,258us-gaap_Goodwill	268,376us-gaap_Goodwill
Indefinite-lived intangible assets, net carrying value	23,920	23,920	23,920
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying value	41,334	41,334	41,334
Accumulated amortization	(18,956)	(16,423)	(13,890)
Net carrying value	22,378us-gaap_FiniteLivedIntangibleAssetsNet	24,911us-gaap_FiniteLivedIntangibleAssetsNet	27,444us-gaap_FiniteLivedIntangibleAssetsNet
Amortization of intangible assets	(2,533)	(2,533)
Goodwill, accumulated impairment loss			156
Intangible assets, accumulated impairment loss			6,866
Expected remaining useful life	8 years 9 months 18 days
North American Insurance
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill, end of year	274,341
Reinsurance
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill, end of year	$ 3,917

The accumulated impairment losses related to intangible assets as of the balance sheet date.

No definition available.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of increase (decrease) in carrying value of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

No definition available.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

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-Paragraph 1

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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-Publisher FASB

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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-Publisher FASB

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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