Statutory Requirements (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Statutory Accounting Practices [Line Items]
Retained earnings available for payment of dividends or distribution to shareholders	2,400,000,000	$ 2,600,000,000
Assets held in trust	2,379,400,000us-gaap_AssetsHeldInTrust	2,081,100,000us-gaap_AssetsHeldInTrust
Renaissance Reinsurance \| Bermuda
Statutory Accounting Practices [Line Items]
Unrecorded liabilities, exempt by regulatory authority	468,600,000	168,000,000
Multi-Beneficiary Reinsurance Trust \| Renaissance Reinsurance \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	508,600,000	505,100,000
Multi-Beneficiary Reinsurance Trust \| DaVinciRe \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	173,700,000	173,900,000
Multi-Beneficiary Reduced Collateral Reinsurance Trust \| New York
Statutory Accounting Practices [Line Items]
Multi-beneficiary reduced collateral reinsurance trust collateral reduction	20.00%
Multi-Beneficiary Reduced Collateral Reinsurance Trust \| Renaissance Reinsurance \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	43,200,000	21,100,000
Multi-Beneficiary Reduced Collateral Reinsurance Trust \| DaVinciRe \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	18,800,000	18,600,000
Minimum \| Multi-Beneficiary Reinsurance Trust \| Renaissance Reinsurance \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	409,900,000	441,700,000
Minimum \| Multi-Beneficiary Reinsurance Trust \| DaVinciRe \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	105,700,000	135,200,000
Minimum \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| Renaissance Reinsurance \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	17,500,000	16,300,000
Minimum \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| DaVinciRe \| New York
Statutory Accounting Practices [Line Items]
Assets held in trust	10,300,000	$ 10,200,000

Reduction in collateral requirements of multi-beneficiary reinsurance trust to the percentage noted of the net outstanding insurance liabilities.

No definition available.

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- Definition

Statutory Accounting Practices, Unrecorded Liabilities, Exempt by Regulatory Authority

+ References

No definition available.

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- Definition

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

+ References

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- Definition

Amount of dividends that can be declared or paid without approval of regulatory agency.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(e))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph e

-Article 4

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