Schedule II - Condensed Financial Information of Registrant - Statement of Income and Comprehensive Income (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements Captions [Line Items]
Net investment income									$ 918,625,000	$ 957,716,000	$ 1,012,348,000
Total revenues									6,602,267,000	7,541,234,000	7,232,397,000
Operating expenses									1,341,315,000	1,213,178,000	1,173,955,000
Foreign exchange (gains) losses									(37,568,000)	(28,243,000)	10,545,000
Interest expense									134,106,000	155,462,000	172,204,000
Total expenses									6,343,750,000	6,446,886,000	6,521,873,000
Provision for income tax									(96,897,000)	(77,505,000)	(34,028,000)
Net income (loss) attributable to ordinary shareholders									188,340,000	1,059,916,000	651,128,000
Net income (loss)	139,500,000	72,384,000	(279,261,000)	255,717,000	300,780,000	135,648,000	272,698,000	350,790,000
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax									424,861,000	0	0
Cumulative adjustments recorded to value of future policy benefit reserves, amount									(400,456,000)	(44,660,000)	0
Change in net unrealized gains (losses) on affiliate and other investments, net of tax									35,143,000	26,637,000	46,162,000
Change in OTTI losses recognized in other comprehensive income, net of tax									13,143,000	32,181,000	67,280,000
Change in underfunded pension liability									(7,550,000)	7,653,000	(3,371,000)
Change in value of cash flow hedge									255,000	439,000	439,000
Foreign currency translation adjustments									(25,729,000)	(54,858,000)	(8,156,000)
Comprehensive income (loss)									936,141,000	276,553,000	1,588,083,000
XL Group PLC
Condensed Financial Statements Captions [Line Items]
Net investment income									275,000	24,000	5,000
Total revenues									275,000	24,000	5,000
Operating expenses									9,646,000	11,699,000	10,971,000
Foreign exchange (gains) losses									127,000	243,000	165,000
Interest expense									5,000	2,000	15,000
Total expenses									9,778,000	11,944,000	11,151,000
Income (loss) before income tax									(9,503,000)	(11,920,000)	(11,146,000)
Equity in net earnings (losses) of subsidiaries (dividends were: 2014: $858,521; 2013: $617,719; 2012: nil)									197,843,000	1,071,836,000	662,274,000
Net income (loss) attributable to ordinary shareholders									188,340,000	1,059,916,000	651,128,000
Net income (loss)									188,340,000	1,059,916,000	651,128,000
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax									424,861,000	0	0
Change in net unrealized gains (losses) on affiliate and other investments, net of tax									35,143,000	26,637,000	46,162,000
Change in OTTI losses recognized in other comprehensive income, net of tax									13,143,000	32,181,000	67,280,000
Change in underfunded pension liability									(7,550,000)	7,653,000	(3,371,000)
Change in value of cash flow hedge									255,000	439,000	439,000
Foreign currency translation adjustments									(25,729,000)	(54,858,000)	(8,156,000)
Comprehensive income (loss)									936,141,000	276,553,000	1,588,083,000
Parenthetical information, dividends:
Dividends received from subsidiaries									858,521,000	617,719,000	0
Dividends and Return of Capital Received From Subsidiary									940,000,000	702,000,000	342,000,000
Life Funds Withheld Assets [Member]
Condensed Financial Statements Captions [Line Items]
Net investment income									129,575,000	0	0
Change in net unrealized gains (losses) on investments, net of tax									274,083,000	0	0
Life Funds Withheld Assets [Member] | XL Group PLC
Condensed Financial Statements Captions [Line Items]
Change in net unrealized gains (losses) on investments, net of tax									274,083,000	0	0
Exclude Life Funds Withheld Assets [Member]
Condensed Financial Statements Captions [Line Items]
Net investment income									789,050,000	957,716,000	1,012,348,000
Change in net unrealized gains (losses) on investments, net of tax									434,051,000	(750,755,000)	834,601,000
Exclude Life Funds Withheld Assets [Member] | XL Group PLC
Condensed Financial Statements Captions [Line Items]
Change in net unrealized gains (losses) on investments, net of tax									434,051,000	(750,755,000)	834,601,000
Unrealized Gains (Losses) on Investments
Condensed Financial Statements Captions [Line Items]
Provision for income tax									(1,593,000)	5,183,000
Cumulative adjustments recorded to value of future policy benefit reserves, amount									(400,456,000)
Unrealized Gains (Losses) on Investments | XL Group PLC
Condensed Financial Statements Captions [Line Items]
Cumulative adjustments recorded to value of future policy benefit reserves, amount									$ (400,456,000)	$ (44,660,000)	$ 0