CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Revenues:
Net premiums earned	$ 1,436,418	$ 1,361,383
Net investment income	265,242	280,263
Realized investment gains (losses):
Net realized gains (losses) on investments sold	41,768	(28,992)
Other-than-temporary impairments on investments	(18,565)	(33,720)
Other-than-temporary impairments on investments transferred to (from) other comprehensive income	(2,400)	(3,725)
Total net realized gains (losses) on investments	20,803	(66,437)
Net realized and unrealized gains (losses) on derivative instruments	702	3,567
Income (loss) from investment fund affiliates	19,408	27,150
Fee income and other	9,859	8,932
Total revenues	1,752,432	1,614,858
Expenses:
Net losses and loss expenses incurred	854,065	1,208,865
Claims and policy benefits	121,307	133,231
Acquisition costs	224,151	188,490
Operating expenses	282,411	260,992
Exchange (gains) losses	12,718	9,514
Interest expense	39,298	54,147
Total expenses	1,533,950	1,855,239
Income (loss) before income tax and income (loss) from operating affiliates	218,482	(240,381)
Income (loss) from operating affiliates	16,253	13,636
Provision (benefit) for income tax	21,550	(32,797)
Net income (loss)	213,185	(193,948)
Non-controlling interests	(36,557)	(33,336)
Net income (loss) attributable to XL Group plc and ordinary shareholders	$ 176,628	$ (227,284)
Weighted average ordinary shares and ordinary share equivalents outstanding – basic (in Shares)	315,120	311,478
Weighted average ordinary shares and ordinary share equivalents outstanding – diluted (in Shares)	317,639	311,478
Earnings (loss) per ordinary share and ordinary share equivalent – basic (in Dollars per share)	$ 0.56	$ (0.73)
Earnings (loss) per ordinary share and ordinary share equivalent – diluted (in Dollars per share)	$ 0.56	$ (0.73)