Sale of Life Reinsurance Subsidiary - Impact of Life Retro arrangements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	4 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Life Funds Withheld Assets	Sep. 30, 2013 Life Funds Withheld Assets	Sep. 30, 2014 Life Funds Withheld Assets	Sep. 30, 2013 Life Funds Withheld Assets	Sep. 30, 2014 Life Funds Withheld Assets XL Re Life (SAC) Ltd [Member]	Sep. 30, 2014 Life Funds Withheld Assets XL Re Life (SAC) Ltd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Underwriting profit (loss)	$ 139,138	$ 26,265	$ 371,443	$ 194,439					$ 3,711	$ 3,711
Net investment income	226,430	237,921	692,392	716,935	56,474	0	75,639	0	56,474	75,639
Net realized gains (losses) on investments sold					2,022	0	2,646	0	2,022	2,646
OTTI on investments					(7,494)	0	(16,265)	0	(7,494)	(16,265)
Exchange (gains) losses	23,348	(20,303)	(8,234)	24,463					2,062	2,062
Other income and expenses	(3,058)	(1,547)	(6,410)	(2,602)					124	105
Net realized and unrealized gains (losses) on life retrocession embedded derivative	5,131	880	18,540	3,660	(201,264)	0	(218,810)	0	(201,264)	(218,810)
Net income (loss)	109,967	170,670	125,864	833,080					(144,365)	(150,912)
Change in net unrealized gains (losses) on investments, net of tax					93,921	0	106,218	0	93,921	106,218
Change in adjustments related to future policy benefit reserves, net of tax									51,286	51,286
Change in cumulative translation adjustment	(11,814)	4,020	(25,295)	(23,616)					2,869	(2,881)
Comprehensive income (loss)	$ 24,894	$ 51,556	$ 495,272	$ (757,704)					$ 3,711	$ 3,711