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	Series E Preference Ordinary Shares
Balance, beginning of year at Dec. 31, 2009		$ 3,421	$ 10,474,688	$ (1,142,467)	$ 81,180	$ 2,305	$ 10
Issuance of ordinary shares		0	1,109
Buybacks of ordinary shares		(256)	(521,664)
Exercise of stock options		0
Exercise of stock options, net of tax			1,182
Share based compensation expense			37,691
Impact of adoption of new authoritative embedded derivative guidance, net of taxes	31,917			31,917	(31,917)
Change in net unrealized gains (losses) on investments, net of tax	997,066			997,066
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	44,314			44,314
Change in OTTI losses recognized in other comprehensive income, net of tax	124,906			124,906
Change in underfunded pension liability	(2,619)			(2,619)
Change in net unrealized gain (loss) on future policy benefit reserves	(3,714)			(3,714)
Change in value of cash flow hedge	439			439
Foreign currency translation adjustments	50,953			50,953
Net income (loss) attributable to XL Group plc	603,550				603,550
Dividends on ordinary shares					(134,238)
Dividends on Series C and Series E preference ordinary shares	(34,694)				(34,694)
Gain on redemption of Redeemable Series C preference ordinary shares	16,616				16,616
Non-controlling interests - contribution						0
Non-controlling interests						4
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(13)
Transfer from Series E preference ordinary shares and additional paid in capital			(999,990)			1,000,000	(10)
Issuance of preference ordinary shares						0
Purchase of Series D preference ordinary shares						0
Purchase of Series E preference ordinary shares						0
Balance, end of year at Dec. 31, 2010	10,599,769	3,165	8,993,016	100,795	500,497	1,002,296
Issuance of ordinary shares		307	572,708
Buybacks of ordinary shares		(317)	(666,705)
Exercise of stock options		1
Exercise of stock options, net of tax			1,333
Share based compensation expense			38,327
Impact of adoption of new authoritative embedded derivative guidance, net of taxes	0				0
Change in net unrealized gains (losses) on investments, net of tax	446,427			446,427
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	25,269			25,269
Change in OTTI losses recognized in other comprehensive income, net of tax	39,456			39,456
Change in underfunded pension liability	(2,622)			(2,622)
Change in net unrealized gain (loss) on future policy benefit reserves	0			0
Change in value of cash flow hedge	439			439
Foreign currency translation adjustments	(26,700)			(26,700)
Net income (loss) attributable to XL Group plc	(474,760)				(474,760)
Dividends on ordinary shares					(138,978)
Dividends on Series C and Series E preference ordinary shares	0				0
Gain on redemption of Redeemable Series C preference ordinary shares	0				0
Non-controlling interests - contribution						0
Non-controlling interests						(83)
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(2,241)
Transfer from Series E preference ordinary shares and additional paid in capital			0			0	0
Issuance of preference ordinary shares						350,000
Purchase of Series D preference ordinary shares						(5,000)
Purchase of Series E preference ordinary shares						(500)
Balance, end of year at Dec. 31, 2011	10,756,130	3,156	8,938,679	583,064	(113,241)	1,344,472	0
Issuance of ordinary shares		10	1,387
Buybacks of ordinary shares		(183)	(402,747)
Exercise of stock options		4
Exercise of stock options, net of tax			5,545
Share based compensation expense			41,889
Impact of adoption of new authoritative embedded derivative guidance, net of taxes	0				0
Change in net unrealized gains (losses) on investments, net of tax	841,213			841,213
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	46,163			46,163
Change in OTTI losses recognized in other comprehensive income, net of tax	67,280			67,280
Change in underfunded pension liability	(9,985)			(9,985)
Change in net unrealized gain (loss) on future policy benefit reserves	0			0
Change in value of cash flow hedge	439			439
Foreign currency translation adjustments	(8,163)			(8,163)
Net income (loss) attributable to XL Group plc	651,134				651,134
Dividends on ordinary shares					(135,572)
Dividends on Series C and Series E preference ordinary shares	0				0
Gain on redemption of Redeemable Series C preference ordinary shares	0				0
Non-controlling interests - contribution						1,500
Non-controlling interests						113
Non-controlling interest share in change in accumulated other comprehensive income (loss)						240
Transfer from Series E preference ordinary shares and additional paid in capital			0			0	0
Issuance of preference ordinary shares						0
Purchase of Series D preference ordinary shares						0
Purchase of Series E preference ordinary shares						0
Balance, end of year at Dec. 31, 2012	$ 11,856,397	$ 2,987	$ 8,584,753	$ 1,520,011	$ 402,321	$ 1,346,325	$ 0