Unpaid Losses and Loss Expenses and Policy Benefits for Life and Annuity Contracts Non Life loss and loss expenses rollforward (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Non-Life loss and loss expenses rollforward [Abstract]
Gross liability at beginning of year	$ 10,646,318	$ 10,709,371	$ 11,273,091
Reinsurance recoverable at beginning of year	267,384pre_ReinsuranceRecoverablesNonLife	291,330pre_ReinsuranceRecoverablesNonLife	353,105pre_ReinsuranceRecoverablesNonLife
Net liability at beginning of year	10,378,934	10,418,041	10,919,986
Current year	3,122,981	3,118,755	2,785,694
Prior years	(660,413)	(721,499)	(628,065)
Total Non-life Incurred Claims	2,462,568	2,397,256	2,157,629
Change in Paris Re Reserve Agreement	(25,412)pre_ChangeInReserveAgreement	(49,544)pre_ChangeInReserveAgreement	(86,163)pre_ChangeInReserveAgreement
Current year	267,806	242,053	237,783
Prior years	2,530,743	2,159,506	2,467,279
Total Non-life Claims Paid	2,798,549	2,401,559	2,705,062
Effects of foreign exchange rate changes	(486,084)pre_EffectOfForeignExchangeRateChanges	14,740pre_EffectOfForeignExchangeRateChanges	131,651pre_EffectOfForeignExchangeRateChanges
Net liability at end of year	9,531,457	10,378,934	10,418,041
Reinsurance recoverable at end of year	214,349pre_ReinsuranceRecoverablesNonLife	267,384pre_ReinsuranceRecoverablesNonLife	291,330pre_ReinsuranceRecoverablesNonLife
Gross liability at end of year	$ 9,745,806	$ 10,646,318	$ 10,709,371

Amount of development on net reserves acquired which are subject to a guarantee provided.

No definition available.

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This element represents the change in the net liability resulting from the fluctuation of foreign exchange rates during the period

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No definition available.

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The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, net of any related valuation allowance.

+ References

No definition available.

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- Definition

The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

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Amount of payments to settle claims incurred in the current period and related claims settlement costs.

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Amount of payments to settle claims incurred in prior periods and related claims settlement costs.

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Amount of expense for claims incurred and costs incurred in the claim settlement process.

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Liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims. This includes an estimate for claims which have been incurred but not reported. Claim adjustment expenses represent the costs estimated to be incurred in the settlement of unpaid claims.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

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Amount of payments to settle insured claims and pay costs incurred in the claims settlement process.

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Amount of expense for claims incurred in the current reporting period and related claims settlement costs.

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Amount of expense for claims incurred in prior reporting periods and related claims settlement costs.

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