UNAUDITED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands	Total	Ordinary Shares	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)	Non-controlling Interest in Equity of Consolidated Subsidiaries
Balance, beginning of year at Dec. 31, 2011		$ 3,156	$ 8,938,679	$ 583,064	$ (113,241)	$ 1,344,472
Issuance of ordinary shares		8	7
Buybacks of ordinary shares		(48)	(100,442)		0
Exercise of stock options		1
Exercise of stock options			942
Share-based compensation expense			7,646
Change in net unrealized gains (losses) on investments, net of tax	212,324			212,324
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	15,050			15,050
Change in OTTI losses recognized in other comprehensive income, net of tax	12,421			12,421
Change in underfunded pension liability	(174)			(174)
Change in value of cash flow hedge	110			110
Foreign currency translation adjustments	8,721			8,721
Net income (loss) attributable to XL Group plc	176,628				176,628
Dividends on ordinary shares					(34,830)
Non-controlling interests - distribution						0
Non-controlling interests						0
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(5)
Non-controlling interests - deconsolidation						0
Balance, end of year at Mar. 31, 2012	11,054,489	3,117	8,846,832	831,516	28,557	1,344,467
Balance, beginning of year at Dec. 31, 2012	11,856,397	2,987	8,584,753	1,520,011	402,321	1,346,325
Issuance of ordinary shares		8	7
Buybacks of ordinary shares	(223,300)	(80)	(220,572)		(3,767)
Exercise of stock options		3
Exercise of stock options			4,313
Share-based compensation expense			3,026
Change in net unrealized gains (losses) on investments, net of tax	(112,222)			(112,222)
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	(4,435)			(4,435)
Change in OTTI losses recognized in other comprehensive income, net of tax	5,182			5,182
Change in underfunded pension liability	385			385
Change in value of cash flow hedge	110			110
Foreign currency translation adjustments	(3,921)			(3,921)
Net income (loss) attributable to XL Group plc	350,790				350,790
Dividends on ordinary shares					(41,553)
Non-controlling interests - distribution						(37)
Non-controlling interests						82
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(29)
Non-controlling interests - deconsolidation						(1,841)
Balance, end of year at Mar. 31, 2013	$ 11,831,846	$ 2,918	$ 8,371,527	$ 1,405,110	$ 707,791	$ 1,344,500