CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Net premiums earned	$ 6,090,441	$ 5,690,130	$ 5,414,061
Net investment income	1,012,348	1,137,769	1,198,038
Realized investment gains (losses):
Net realized gains (losses) on investments sold	94,810	(28,187)	(65,670)
Other-than-temporary impairments on investments	(54,306)	(174,102)	(170,643)
Other-than-temporary impairments on investments transferred to (from) other comprehensive income	(26,406)	13,930	(34,490)
Total net realized gains (losses) on investments	14,098	(188,359)	(270,803)
Net realized and unrealized gains (losses) on derivative instruments	5,221	(10,738)	(33,843)
Income (loss) from investment fund affiliates	58,504	26,253	51,102
Fee income and other	49,868	41,748	40,027
Total revenues	7,230,480	6,696,803	6,398,582
Expenses:
Net losses and loss expenses incurred	3,765,482	4,078,391	3,211,800
Claims and policy benefits	486,198	535,074	513,833
Acquisition costs	913,492	826,411	788,258
Operating expenses	1,173,951	1,083,917	972,963
Exchange gains (losses)	10,546	(40,640)	(10,161)
Interest expense	172,205	205,592	213,643
Impairment of goodwill	0	429,020	0
Loss on termination of guarantee	0	0	23,500
Total expenses	6,521,874	7,117,765	5,713,836
Income (loss) before income tax and income (loss) from operating affiliates	708,606	(420,962)	684,746
Income (loss) from operating affiliates	55,810	76,786	121,372
Provision (benefit) for income tax	34,028	59,707	162,737
Net income (loss)	730,388	(403,883)	643,381
Non-controlling interests	(79,254)	(70,877)	(39,831)
Net income (loss) attributable to XL Group plc and ordinary shareholders	651,134	(474,760)	603,550
Dividends on Series C and Series E preference ordinary shares	0	0	(34,694)
Gain on redemption of Redeemable Series C preference ordinary shares	0	0	16,616
Net income (loss) attributable to ordinary shareholders	$ 651,134	$ (474,760)	$ 585,472
Weighted average ordinary shares and ordinary share equivalents outstanding - basic (in shares)	307,372	312,896	336,283
Weighted average ordinary shares and ordinary share equivalents outstanding - diluted (in shares)	310,282	312,896	337,709
Earnings (loss) per ordinary share and ordinary share equivalent - basic (in dollars per share)	$ 2.12	$ (1.52)	$ 1.74
Earnings (loss) per ordinary share and ordinary share equivalent - diluted (in dollars per share)	$ 2.10	$ (1.52)	$ 1.73