SCHEDULE IICONDENSED FINANCIAL INFORMATION OF REGISTRANTCONDENSED BALANCE SHEETS - PARENT COMPANY ONLY (Tables)

12 Months Ended

Dec. 31, 2011

Condensed Consolidated Balance Sheets [Table Text Block]

(U.S. dollars in thousands)	2011			2010
Assets
Cash and cash equivalents	$	1,644		$	2,816
Amounts due from subsidiaries		80,841			—
Investments in subsidiaries on an equity basis		9,374,825			9,750,149
Other assets		3,797			901
Total assets	$	9,461,107		$	9,753,866
Liabilities
Amounts due to subsidiaries (1)	$	—		$	125,052
Accounts payable and accrued liabilities		19,145			1,857
Total liabilities	$	19,145		$	126,909
Commitments and Contingencies
Shareholders’ Equity:
Ordinary shares, 999,990,000 authorized, par value $0.01 Issued and outstanding: (2011, 315,645,796; 2010, 316,396,289)	$	3,157		$	3,165
Additional paid in capital		8,955,702			9,009,220
Accumulated other comprehensive Income (loss)		583,064			100,795
Retained earnings (deficit)		(99,961	)		513,777
Total shareholders’ equity	$	9,441,962		$	9,626,957
Total liabilities and shareholders’ equity	$	9,461,107		$	9,753,866

Consolidated Statement Of Income And Comprehensive Income [Table Text Block]

	XL Group plc						XLIT Ltd. (1)
(U.S. dollars in thousands)	Year Ended December 31, 2011			July 1 to December 31, 2010			January 1 to June 30, 2010			Year Ended December 31, 2009
Net investment income	$	2		$	—		$	44,636		$	20,245
Realized investment gains (losses):		—
Net realized gains (losses) on investments sold		—			—			25,177			(5,453	)
Other-than-temporary impairments on investments		—			—			(11,670	)		(8,468	)
Other-than-temporary impairments on investments transferred to other comprehensive income		—			—			4			1,319
Total net realized gains (losses) on investments		—			—			13,511			(12,602	)
Net realized and unrealized gains (losses) on derivative instruments		—			—			(4,087	)		(8,830	)
Equity in net earnings (losses) of subsidiaries (Dividends were $183,029 in 2011 $197,326 and $448,400 in 2010 and $2,091,474 in 2009)		(400,612	)		275,629			384,311			310,490
Equity in net earnings of affiliates					—			2			1,221
Total revenues	$	(400,610	)	$	275,629		$	438,373		$	310,524
Operating expenses		74,422			9,930			48,256			107,211
Foreign exchange (gains) losses		(275	)		34			1,003			(122	)
Interest expense		3			—			51,431			122,662
Total expenses	$	74,150		$	9,964		$	100,690		$	229,751
Income (loss) before income tax		(474,760	)		265,665			337,683			80,773
Provision for income tax		—			—			(202	)		5,782
Net income (loss)	$	(474,760	)	$	265,665		$	337,885		$	74,991
Preference share dividends		—			—			(34,694	)		(80,200	)
Gain on redemption of Redeemable Series C preference ordinary shares		—			—			16,616			211,816
Net income (loss) attributable to ordinary shareholders	$	(474,760	)	$	265,665		$	319,807		$	206,607
Net income (loss)	$	(474,760	)	$	265,665		$	337,885		$	74,991
Impact of adoption of new authoritative OTTI guidance, net of taxes		—			—			—			(229,670	)
Impact of adoption of new authoritative embedded derivative guidance, net of taxes		—			31,917			—			—
Change in net unrealized gains (losses) on investment portfolio, net of tax		471,696			161,048			880,332			2,391,020
Change in OTTI losses recognized in other comprehensive income, net of tax		39,456			93,269			31,637			(123,343	)
Change in underfunded pension liability		(2,622	)		(6,186	)		3,567			(3,427	)
Change in value of cash flow hedge		439			219			220			438
Change in net unrealized gains (losses) on future policy benefit reserves		—			—			(3,714	)		6,554
Foreign currency translation adjustments		(26,700	)		159,261			(108,308	)		180,888
Comprehensive income (loss)	$	7,509		$	705,193		$	1,141,619		$	2,297,451

Condensed Statement Of Cash Flows [Table Text Block]

	XL Group plc						XLIT Ltd. (1)
(U.S. dollars in thousands)	Year Ended December 31, 2011			July 1 to December 31, 2010			January 1 to June 30, 2010			Year Ended December 31, 2009
Net income (loss)	$	(474,760	)	$	265,665		$	337,885		$	74,991
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Net realized (gains) losses on investments and derivative instruments		—			—			(9,423	)		21,432
Equity in (earnings) loss of subsidiaries		400,612			(275,629	)		(384,311	)		(310,490	)
Equity in net (income) of affiliates					—			(2	)		(1,221	)
Share based compensation		29,377			15,705			15,586			32,231
Amortization of premiums (discounts) on fixed maturities		—			—			(9,791	)		221
Accretion of notes payable and debt		—			—			341			681
Accounts payable and accrued liabilities		—			—			(24,973	)		(57,806	)
Amounts due to (from) subsidiaries		(205,893	)		125,052			(183,273	)		(3,259,462	)
Dividends received from subsidiaries		183,029			448,400			197,326			2,091,474
Other		22,804			7,914			30,936			17,432
Total adjustments		429,929			321,442			(367,584	)		(1,465,508	)
Net cash provided by (used in) operating activities	$	(44,831	)	$	587,107		$	(29,699	)	$	(1,390,517	)
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	—		$	369,752		$	245,629
Proceeds from redemption of fixed maturities and short-term investments		—			—			575,326			2,860,755
Proceeds from sale of equity securities		—			—			238			—
Purchases of fixed maturities and short term investments		—			—			(919,840	)		(4,475,472	)
Investment in subsidiaries		272,398			—			298,119			1,955,045
Investment in affiliates		—			—			5			1,743
Investment in limited partnerships		—			—			95			347
Net cash provided by (used in) investing activities	$	272,398		$	—		$	323,695		$	588,047
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	576,333		$	1,182		$	—		$	745,000
Repurchase of Series E preference ordinary shares		—			—			(94,157	)		(104,718	)
Dividends paid		(138,050	)		(65,350	)		(106,471	)		(225,008	)
Buybacks of ordinary shares		(667,022	)		(520,184	)		(1,840	)		(626	)
Repayment of debt		—			—			—			(745,000	)
Net cash provided by (used in) financing activities	$	(228,739	)	$	(584,352	)	$	(202,468	)	$	(330,352	)
Net change in cash and cash equivalents		(1,172	)		2,755			91,528			(1,132,822	)
Cash and cash equivalents – beginning of period		2,816			61			600,993			1,733,815
Cash and cash equivalents – end of period	$	1,644		$	2,816		$	692,521		$	600,993