STATUTORY FINANCIAL DATA (Detail) (USD $)		12 Months Ended				12 Months Ended						12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 Bermuda [Member]		Dec. 31, 2010 Bermuda [Member]		Dec. 31, 2011 U.S [Member]		Dec. 31, 2010 U.S [Member]		Dec. 31, 2011 Ireland [Member]	Dec. 31, 2011 U.K [Member]	Dec. 31, 2009 International Subsidiaries [Member]
BSCR level for certain operating subsidiaries		100.00%
RBC Level						100.00%
Cap On Declaration Or Payments of Dividends		25%				lesser of 10 percent of XLRA's statutory policyholders' surplus or 100 percent of its "adjusted net investment income
Statutory Accounting Practices Statutory Capital And Surplus Maximum Dividend		$ 1,300,000,000		$ 1,300,000,000
Statutory Accounting Practices Statutory Capital And Surplus Earned						59,700,000		184,300,000
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		9,140,393,000	[1],[2]	9,159,021,000	[1],[2]	2,093,694,000	[2],[3]	2,273,711,000	[2],[3]
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments	59,700,000
Statutory Accounting Practices Statutory Capital And Surplus Outside Of US And Bermuda										1,500,000,000	1,100,000,000
Minimum Required Capital Level Ireland												$ 1,500,000,000

[1] Required statutory capital and surplus represents 100% BSCR level for principal Bermuda operating subsidiaries.

[2] Statutory assets in Bermuda include investments in other U.S. and international subsidiaries reported separately herein.

[3] Required statutory capital and surplus represents 100% RBC level for principal U.S. operating subsidiaries.