CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income (loss) attributable to XL Group plc	$ (474,760)	$ 603,550	$ 74,991
Impact of adoption of new authoritative OTTI guidance, net of taxes	0	0	(229,670)
Impact of adoption of new authoritative embedded derivative guidance, net of taxes	0	31,917	0
Change in net unrealized gains (losses) on investments, net of tax	446,427	997,066	2,376,556
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	25,269	44,314	14,464
Change in OTTI losses recognized in other comprehensive income, net of tax	39,456	124,906	(123,343)
Change in underfunded pension liability	(2,622)	(2,619)	(3,427)
Change in value of cash flow hedge	439	439	438
Change in net unrealized gains (losses) on future policy benefit reserves	0	(3,714)	6,554
Foreign currency translation adjustments	(26,700)	50,953	180,888
Comprehensive income (loss)	$ 7,509	$ 1,846,812	$ 2,297,451