CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands	Common Stock [Member] Common Class A [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member] Series E Preferred Stock [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2010	$ 3,165	$ 8,993,016	$ 100,795	$ 500,497		$ 1,002,296
Non-controlling interests						4	33,336
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(2)
Purchase of Series E preference ordinary shares					(500)
Net income attributable to XL Group plc				(227,284)			(227,284)
Dividends on ordinary shares				(34,251)
Change in net unrealized gains (losses) on investments, net of tax			13,379
Change in net unrealized gains (losses) on affiliate and investments, net of tax			24,235				24,235
Change in OTTI losses recognized in other comprehensive income, net of tax			25,307
Change in underfunded pension liability			(344)				344
Change in value of cash flow hedge			110				110
Foreign currency translation adjustments			11,616				11,616
Issuance of ordinary shares	2	8
Buybacks of ordinary shares	(73)	(166,429)
Exercise of stock options, net of tax		0
Share based compensation expense		10,169
Exercise of stock options	0
Balance at Mar. 31, 2011	3,094	8,836,764	175,098	238,962		1,001,798	10,255,716
Balance at Dec. 31, 2011	3,156	8,938,679	583,064	(113,241)		1,344,472	10,756,130
Non-controlling interests						0	36,557
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(5)
Purchase of Series E preference ordinary shares					0
Net income attributable to XL Group plc				176,628			176,628
Dividends on ordinary shares				(34,830)
Change in net unrealized gains (losses) on investments, net of tax			212,324
Change in net unrealized gains (losses) on affiliate and investments, net of tax			15,050				15,050
Change in OTTI losses recognized in other comprehensive income, net of tax			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
Issuance of ordinary shares	8	7
Buybacks of ordinary shares	(48)	(100,442)
Exercise of stock options, net of tax		942
Share based compensation expense		7,646
Exercise of stock options	1
Balance at Mar. 31, 2012	$ 3,117	$ 8,846,832	$ 831,516	$ 28,557		$ 1,344,467	$ 11,054,489