Subsequent Events (Notes)	12 Months Ended
Dec. 31, 2014
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events Catlin Acquisition On January 9, 2015, the Company entered into an implementation agreement (the “Implementation Agreement”) with Catlin Group Limited (“Catlin”) and Green Holdings Limited, a direct, wholly-owned subsidiary of the Company (“Green Holdings”), pursuant to which the Company will acquire the entire issued and to be issued share capital of Catlin (the “Acquisition”) for cash and newly-issued ordinary shares of the Company. The Acquisition is intended to be effected by means of a two-step, integrated process comprising a scheme of arrangement (the “Scheme”) under Section 99 of the Companies Act 1981 Bermuda, as amended (the “Companies Act”), which is required to be sanctioned by the Supreme Court of Bermuda, followed immediately by a merger of Catlin with and into Green Holdings under Section 104H of the Companies Act. In certain circumstances set forth in the Implementation Agreement, the Acquisition may alternatively be effected by means of a takeover offer or by a single-step merger of Catlin with and into Green Holdings under the Companies Act. Under the terms of the Acquisition, Catlin shareholders will be entitled to receive 388 pence in cash and 0.130 ordinary shares of the Company, in exchange for each Catlin common share, par value $0.01 per share (“Catlin Shares”), subject to the proration and adjustment mechanisms set forth in the Implementation Agreement. On the basis of the closing price of an ordinary share of the Company on January 8, 2015 of $35.42, the Acquisition values Catlin at 693 pence per Catlin Share, representing a transaction equity value of approximately $4.1 billion. It is intended that the newly-issued ordinary shares of the Company will be listed on the New York Stock Exchange following the completion of the Acquisition. For further information on the Acquisition, see the Company’s Report on Form 8-K filed with the U.S. Securities Exchange Commission (the “SEC”) under Items 1.01, 2.03. 3.02, 8.01 and 9.01 on January 9, 2015. In connection with the Acquisition, on January 9, 2015, the Company, Green Holdings and Catlin entered into a Merger Agreement (the “Merger Agreement”), which provides for the merger of Catlin with and into Green Holdings pursuant to Section 104H of the Bermuda Companies Act, with Green Holdings continuing as the surviving company (the “Merger”). If the Implementation Agreement is terminated, or if the Company publicly announces that the Acquisition will be implemented by another means in accordance with the Implementation Agreement, the Merger Agreement will terminate. The parties’ respective boards of directors have approved the Merger and the Merger Agreement. The Company, as sole shareholder of Green Holdings, has approved the Merger and the Merger Agreement, and immediately following effectiveness of the Scheme, XL, as sole shareholder of Catlin, will approve the Merger and the Merger Agreement. The Scheme and the Merger are intended to be a single, integrated transaction that qualifies as a reorganization for U.S. federal income tax purposes. On January 9, 2015, the Company entered into contingent deliverable foreign exchange forwards with Morgan Stanley Capital Services LLC and Goldman Sachs International. The purpose of these transactions is to mitigate risk of foreign currency exposure related to the pending Acquisition and in general, these transactions will terminate without any payments due by any of the parties if the Acquisition does not close on or before October 9, 2015. On January 9, in connection with the Acquisition, XL-Cayman, as borrower, XL-Ireland, X.L. America, Inc., XL Insurance (Bermuda) Ltd, XL Re Ltd, and XL Life Ltd, as guarantors, Morgan Stanley Senior Funding, Inc., as administrative agent, and the lenders party thereto entered into a senior unsecured 364-Day Bridge Loan Agreement (the “Bridge Loan Agreement”) providing for a £1.6 billion bridge loan facility (the “Bridge Facility”). The proceeds of the Bridge Facility may be used to finance the payment of the cash consideration in connection with the Acquisition and to pay fees and expenses related thereto. The Bridge Loan Agreement contains financial covenants that require the Company to maintain a minimum consolidated net worth and a maximum ratio of total consolidated debt to the sum of total consolidated debt plus consolidated net worth, and that require each of XL Insurance (Bermuda) Ltd, XL Re Ltd and XL Re Europe SE to maintain a financial strength rating of no less than “A-” from A.M. Best & Co. The terms of the Bridge Facility also include customary affirmative covenants, negative covenants and events of default similar to those under our Syndicated Credit Agreement with additional covenants related to the Acquisition and mandatory commitment reduction and loan prepayment provisions in connection with asset sales and debt and equity issuances. If an event of default under the Bridge Loan Agreement shall occur and be continuing, the maturity of such loans (to the extent funded) and all other obligations of XL-Cayman under the Bridge Loan Agreement may be accelerated and all commitments terminated. For further information on the Bridge Facility, see the Company’s Report on Form 8-K filed with the SEC on January 9, 2015 under Items 1.01, 2.03, 8.01 and 9.01. Sale of Strategic Operating Affiliate On December 15, 2014, XL Re Ltd ("XL Re"), an indirect wholly-owned subsidiary of the Company, and other shareholders of ARX entered into a Stock Purchase Agreement with Progressive to sell all of its shares in ARX to Progressive. XL Re's shares in ARX represented approximately 40% of ARX's outstanding capital stock on a fully diluted basis at the time of the announcement. At December 31, 2014, the Company recorded XL Re's shares in ARX as $204.4 million, included within Investments in Affiliates. The transaction is expected to close in the second quarter of 2015 and is subject to regulatory approvals and satisfaction of other closing conditions. XL Re anticipates proceeds of approximately $500 million related to the sale, which will be based upon the consolidated tangible net book value of ARX and its subsidiaries at December 31, 2014, and certain other factors.

Subsequent Events

Catlin Acquisition

On January 9, 2015, the Company entered into an implementation agreement (the “Implementation Agreement”) with Catlin Group Limited (“Catlin”) and Green Holdings Limited, a direct, wholly-owned subsidiary of the Company (“Green Holdings”), pursuant to which the Company will acquire the entire issued and to be issued share capital of Catlin (the “Acquisition”) for cash and newly-issued ordinary shares of the Company. The Acquisition is intended to be effected by means of a two-step, integrated process comprising a scheme of arrangement (the “Scheme”) under Section 99 of the Companies Act 1981 Bermuda, as amended (the “Companies Act”), which is required to be sanctioned by the Supreme Court of Bermuda, followed immediately by a merger of Catlin with and into Green Holdings under Section 104H of the Companies Act. In certain circumstances set forth in the Implementation Agreement, the Acquisition may alternatively be effected by means of a takeover offer or by a single-step merger of Catlin with and into Green Holdings under the Companies Act. Under the terms of the Acquisition, Catlin shareholders will be entitled to receive 388 pence in cash and 0.130 ordinary shares of the Company, in exchange for each Catlin common share, par value $0.01 per share (“Catlin Shares”), subject to the proration and adjustment mechanisms set forth in the Implementation Agreement. On the basis of the closing price of an ordinary share of the Company on January 8, 2015 of $35.42, the Acquisition values Catlin at 693 pence per Catlin Share, representing a transaction equity value of approximately $4.1 billion. It is intended that the newly-issued ordinary shares of the Company will be listed on the New York Stock Exchange following the completion of the Acquisition. For further information on the Acquisition, see the Company’s Report on Form 8-K filed with the U.S. Securities Exchange Commission (the “SEC”) under Items 1.01, 2.03. 3.02, 8.01 and 9.01 on January 9, 2015.

In connection with the Acquisition, on January 9, 2015, the Company, Green Holdings and Catlin entered into a Merger Agreement (the “Merger Agreement”), which provides for the merger of Catlin with and into Green Holdings pursuant to Section 104H of the Bermuda Companies Act, with Green Holdings continuing as the surviving company (the “Merger”). If the Implementation Agreement is terminated, or if the Company publicly announces that the Acquisition will be implemented by another means in accordance with the Implementation Agreement, the Merger Agreement will terminate. The parties’ respective boards of directors have approved the Merger and the Merger Agreement. The Company, as sole shareholder of Green Holdings, has approved the Merger and the Merger Agreement, and immediately following effectiveness of the Scheme, XL, as sole shareholder of Catlin, will approve the Merger and the Merger Agreement. The Scheme and the Merger are intended to be a single, integrated transaction that qualifies as a reorganization for U.S. federal income tax purposes.

On January 9, 2015, the Company entered into contingent deliverable foreign exchange forwards with Morgan Stanley Capital Services LLC and Goldman Sachs International. The purpose of these transactions is to mitigate risk of foreign currency exposure related to the pending Acquisition and in general, these transactions will terminate without any payments due by any of the parties if the Acquisition does not close on or before October 9, 2015.

On January 9, in connection with the Acquisition, XL-Cayman, as borrower, XL-Ireland, X.L. America, Inc., XL Insurance (Bermuda) Ltd, XL Re Ltd, and XL Life Ltd, as guarantors, Morgan Stanley Senior Funding, Inc., as administrative agent, and the lenders party thereto entered into a senior unsecured 364-Day Bridge Loan Agreement (the “Bridge Loan Agreement”) providing for a £1.6 billion bridge loan facility (the “Bridge Facility”). The proceeds of the Bridge Facility may be used to finance the payment of the cash consideration in connection with the Acquisition and to pay fees and expenses related thereto. The Bridge Loan Agreement contains financial covenants that require the Company to maintain a minimum consolidated net worth and a maximum ratio of total consolidated debt to the sum of total consolidated debt plus consolidated net worth, and that require each of XL Insurance (Bermuda) Ltd, XL Re Ltd and XL Re Europe SE to maintain a financial strength rating of no less than “A-” from A.M. Best & Co. The terms of the Bridge Facility also include customary affirmative covenants, negative covenants and events of default similar to those under our Syndicated Credit Agreement with additional covenants related to the Acquisition and mandatory commitment reduction and loan prepayment provisions in connection with asset sales and debt and equity issuances. If an event of default under the Bridge Loan Agreement shall occur and be continuing, the maturity of such loans (to the extent funded) and all other obligations of XL-Cayman under the Bridge Loan Agreement may be accelerated and all commitments terminated. For further information on the Bridge Facility, see the Company’s Report on Form 8-K filed with the SEC on January 9, 2015 under Items 1.01, 2.03, 8.01 and 9.01.

Sale of Strategic Operating Affiliate

On December 15, 2014, XL Re Ltd ("XL Re"), an indirect wholly-owned subsidiary of the Company, and other shareholders of ARX entered into a Stock Purchase Agreement with Progressive to sell all of its shares in ARX to Progressive. XL Re's shares in ARX represented approximately 40% of ARX's outstanding capital stock on a fully diluted basis at the time of the announcement. At December 31, 2014, the Company recorded XL Re's shares in ARX as $204.4 million, included within Investments in Affiliates.

The transaction is expected to close in the second quarter of 2015 and is subject to regulatory approvals and satisfaction of other closing conditions. XL Re anticipates proceeds of approximately $500 million related to the sale, which will be based upon the consolidated tangible net book value of ARX and its subsidiaries at December 31, 2014, and certain other factors.