Ceded Reinsurance (Effect Of Reinsurance And Retrocessional Activity On Premiums Written And Earned And On Net Claims And Claim Expenses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Premiums written
Direct	$ 10,317	$ 8,463
Assumed	625,101	655,688
Ceded	(198,605)	(171,576)
Net premiums written	436,813	492,575
Premiums earned
Direct	9,873	7,787
Assumed	366,853	357,286
Ceded	(105,471)	(86,408)
Net premiums earned	271,255	278,665
Claims and claim expenses
Gross claims and claim expenses incurred	33,998	15,282
Claims and claim expenses recovered	(6,747)	270
Net claims and claim expenses incurred	$ 27,251	$ 15,552

Premiums assumed and earned for all insurance assumed from other insurers as a result of reinsurance arrangements.

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- Definition

Premiums assumed and earned by another insurer as a result of reinsurance arrangements.

+ References

No definition available.

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Premiums earned directly for all insurance before adding contracts assumed from other insurers or subtracting any amounts assumed by other insurers.

+ References

No definition available.

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Premiums for all insurance assumed from other insurers, that is premiums ceded to the entity by other insurers.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 605

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- Definition

Total consideration paid and payable to reinsurers during the period pursuant to terms of reinsurance arrangements.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

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- Definition

Total consideration paid and payable by direct policyholders for insurance contracts sold by the Entity during the period. This amount does not include premium assumed from or ceded to other insurers.

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

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- Definition

Total provision in the period for future policy benefits, claims incurred and costs incurred in the claims settlement process before the effects of reinsurance arrangements.

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Provision for benefits, claims and claims settlement expenses incurred during the period net of the effects of contracts assumed and ceded.

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Premiums earned on the income statement for all insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers.

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Premiums written for all insurance and reinsurance contracts, after adding premiums assumed from other insurers and subtracting any amounts ceded to another insurer.

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

-Publisher SEC

-Name Regulation S-X (SX)

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The net amount in the period for future policy benefits and costs incurred under policies assumed and estimated recoupments under policies ceded.

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