CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income (loss) attributable to XL Group plc	$ 651,134	$ (474,760)	$ 603,550
Impact of adoption of new authoritative embedded derivative guidance, net of taxes	0	0	31,917
Change in net unrealized gains (losses) on investments, net of tax	841,213	446,427	997,066
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	46,163	25,269	44,314
Change in OTTI losses recognized in other comprehensive income, net of tax	67,280	39,456	124,906
Change in underfunded pension liability	(9,985)	(2,622)	(2,619)
Change in net unrealized gain (loss) on future policy benefit reserves	0	0	(3,714)
Change in value of cash flow hedge	439	439	439
Foreign currency translation adjustments	(8,163)	(26,700)	50,953
Comprehensive income (loss)	$ 1,588,081	$ 7,509	$ 1,846,812