Schedule II - Condensed Financial Information of Registrant - Statement of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements Captions [Line Items]
Net income (loss) attributable to ordinary shareholders	$ 188,340	$ 1,059,916	$ 651,128
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Share based compensation	81,287	46,489	47,472
Other	5,447	9,702	(58,249)
Total adjustments	694,346	(356,670)	325,723
Net cash provided by (used in) operating activities	963,184	779,977	1,056,106
Cash flows provided by (used in) investing activities: [Abstract]
Net cash provided by (used in) investing activities	1,711,621	(1,197,862)	(942,593)
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	6,367	12,623	5,413
Dividends paid	(169,620)	(160,155)	(134,799)
Buybacks of ordinary shares	(801,953)	(675,617)	(402,930)
Net cash provided by (used in) financing activities	(1,863,708)	(394,843)	(1,344,753)
Net change in cash and cash equivalents	720,982	(817,546)	(1,206,747)
Cash and cash equivalents – beginning of period	1,800,832	2,618,378	3,825,125
Cash and cash equivalents – end of period	2,521,814	1,800,832	2,618,378
XL Group PLC
Condensed Financial Statements Captions [Line Items]
Net income (loss) attributable to ordinary shareholders	188,340	1,059,916	651,128
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in (earnings) loss of subsidiaries	(197,843)	(1,071,836)	(662,274)
Share based compensation	81,287	46,489	47,472
Amount due to (from) subsidiaries	(23,819)	104,590	166,853
Dividends received from subsidiaries	858,521	617,719	0
Other	(10,632)	(16,570)	(3,296)
Total adjustments	707,514	(319,608)	(451,245)
Net cash provided by (used in) operating activities	895,854	740,308	199,883
Cash flows provided by (used in) investing activities: [Abstract]
Returns of capital from subsidiaries	79,086	84,589	341,750
Net cash provided by (used in) investing activities	79,086	84,589	341,750
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	6,367	12,623	5,413
Dividends paid	(169,620)	(160,155)	(134,799)
Buybacks of ordinary shares	(801,953)	(675,617)	(402,930)
Net cash provided by (used in) financing activities	(965,206)	(823,149)	(532,316)
Net change in cash and cash equivalents	9,734	1,748	9,317
Cash and cash equivalents – beginning of period	12,709	10,961	1,644
Cash and cash equivalents – end of period	$ 22,443	$ 12,709	$ 10,961