Guarantor Financial Information (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2016

Dec. 31, 2015

Guarantor Financial Information [Abstract]

Condensed Balance Sheet [Table Text Block]

	March 31, 2016
Condensed Consolidating Balance Sheet (U.S. dollars in thousands, except share data)	XL- Ireland		XL-Cayman		Other XL-Ireland Subsidiaries		Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
ASSETS
Investments:
Total investments available for sale	$	—	$	554,958	$	33,288,326	$	—		$	33,843,284
Total investments trading	—		—		1,436,542		—			1,436,542
Investments in affiliates	—		—		1,953,711		—			1,953,711
Other investments	—		959		1,452,931		—			1,453,890
Total investments	$	—	$	555,917	$	38,131,510	$	—		$	38,687,427
Cash and cash equivalents	8,681		287,464		2,524,752		—			2,820,897
Restricted cash	—		—		161,019		—			161,019
Investments in subsidiaries	12,082,624		16,336,128		—		(28,418,752		)	—
Accrued investment income	—		2,654		288,362		—			291,016
Deferred acquisition costs and value of business acquired	—		—		1,057,941		—			1,057,941
Ceded unearned premiums	—		—		2,255,664		—			2,255,664
Premiums receivable	—		—		6,041,000		—			6,041,000
Reinsurance balances receivable	—		—		469,009		—			469,009
Unpaid losses and loss expenses recoverable	—		—		5,374,604		—			5,374,604
Receivable from investments sold	—		—		65,471		—			65,471
Goodwill and other intangible assets	—		—		2,233,597		—			2,233,597
Deferred tax asset	—		—		245,927		—			245,927
Amounts due from subsidiaries / parent	—		—		1,473,030		(1,473,030		)	—
Other assets	1,339		42,782		897,999		—			942,120
Total assets	$	12,092,644	$	17,224,945	$	61,219,885	$	(29,891,782	)	$	60,645,692
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities:
Unpaid losses and loss expenses	$	—	$	—	$	25,913,484	$	—		$	25,913,484
Deposit liabilities	—		—		1,170,595		—			1,170,595
Future policy benefit reserves	—		—		4,020,602		—			4,020,602
Funds withheld on GreyCastle life retrocession arrangements	—		—		998,391		—			998,391
Unearned premiums	—		—		8,217,539		—			8,217,539
Notes payable and debt	—		2,645,647		8,248		—			2,653,895
Reinsurance balances payable	—		—		2,583,962		—			2,583,962
Payable for investments purchased	—		—		74,476		—			74,476
Deferred tax liability	—		—		105,589		—			105,589
Amounts due to subsidiaries / parent	394,351		1,078,679		—		(1,473,030		)	—
Other liabilities	9,549		73,495		1,156,397		—			1,239,441
Total liabilities	$	403,900	$	3,797,821	$	44,249,283	$	(1,473,030	)	$	46,977,974
Shareholders’ Equity:
Shareholders’ equity attributable to XL Group plc	$	11,688,744	$	12,082,624	$	16,336,128	$	(28,418,752	)	$	11,688,744
Non-controlling interest in equity of consolidated subsidiaries	—		1,344,500		634,474		—			1,978,974
Total shareholders’ equity	$	11,688,744	$	13,427,124	$	16,970,602	$	(28,418,752	)	$	13,667,718
Total liabilities and shareholders’ equity	$	12,092,644	$	17,224,945	$	61,219,885	$	(29,891,782	)	$	60,645,692

	December 31, 2015
Condensed Consolidating Balance Sheet (U.S. dollars in thousands, except share data)	XL- Ireland		XL-Cayman		Other XL-Ireland Subsidiaries		Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
ASSETS
Investments:
Total investments available for sale	$	—	$	516,425	$	33,237,473	$	—		$	33,753,898
Total investments trading	—		—		1,296,029		—			1,296,029
Investments in affiliates	—		—		1,708,899		—			1,708,899
Other investments	—		877		1,432,180		—			1,433,057
Total investments	$	—	$	517,302	$	37,674,581	$	—		$	38,191,883
Cash and cash equivalents	11,557		369,997		2,874,682		—			3,256,236
Restricted cash	—		—		154,992		—			154,992
Investments in subsidiaries	11,648,673		15,836,651		—		(27,485,324		)	—
Accrued investment income	—		2,323		310,344		—			312,667
Deferred acquisition costs and value of business acquired	—		—		890,568		—			890,568
Ceded unearned premiums	—		—		1,821,793		—			1,821,793
Premiums receivable	—		—		4,712,493		—			4,712,493
Reinsurance balances receivable	—		—		418,666		—			418,666
Unpaid losses and loss expenses recoverable	—		—		5,262,706		—			5,262,706
Receivable from investments sold	—		—		231,158		—			231,158
Goodwill and other intangible assets	—		—		2,210,266		—			2,210,266
Deferred tax asset	—		—		282,311		—			282,311
Amounts due from subsidiaries / parent	33,417		—		1,054,177		(1,087,594		)	—
Other assets	2,748		44,570		889,881		—			937,199
Total assets	$	11,696,395	$	16,770,843	$	58,788,618	$	(28,572,918	)	$	58,682,938
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities:
Unpaid losses and loss expenses	$	—	$	—	$	25,439,744	$	—		$	25,439,744
Deposit liabilities	—		—		1,168,376		—			1,168,376
Future policy benefit reserves	—		—		4,163,500		—			4,163,500
Funds withheld on GreyCastle life retrocession arrangements	—		—		914,629		—			914,629
Unearned premiums	—		—		7,043,358		—			7,043,358
Notes payable and debt	—		2,644,970		—		—			2,644,970
Reinsurance balances payable	—		—		2,117,727		—			2,117,727
Payable for investments purchased	—		—		130,060		—			130,060
Deferred tax liability	—		—		120,651		—			120,651
Amounts due to subsidiaries / parent	—		1,087,594		—		(1,087,594		)	—
Other liabilities	19,316		45,106		1,221,038		—			1,285,460
Total liabilities	$	19,316	$	3,777,670	$	42,319,083	$	(1,087,594	)	$	45,028,475
Shareholders’ Equity:
Shareholders’ equity attributable to XL Group plc	$	11,677,079	$	11,648,673	$	15,836,651	$	(27,485,324	)	$	11,677,079
Non-controlling interest in equity of consolidated subsidiaries	—		1,344,500		632,884		—			1,977,384
Total shareholders’ equity	$	11,677,079	$	12,993,173	$	16,469,535	$	(27,485,324	)	$	13,654,463
Total liabilities and shareholders’ equity	$	11,696,395	$	16,770,843	$	58,788,618	$	(28,572,918	)	$	58,682,938

	December 31, 2015
Condensed Consolidating Balance Sheet (U.S. dollars in thousands, except share data)	XL- Ireland		XL-Cayman		Other XL-Ireland Subsidiaries		Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
ASSETS
Investments:
Total investments available for sale	$	—	$	516,425	$	33,237,473	$	—		$	33,753,898
Total investments trading	—		—		1,296,029		—			1,296,029
Investments in affiliates	—		—		1,708,899		—			1,708,899
Other investments	—		877		1,432,180		—			1,433,057
Total investments	$	—	$	517,302	$	37,674,581	$	—		$	38,191,883
Cash and cash equivalents	11,557		369,997		2,874,682		—			3,256,236
Restricted cash	—		—		154,992		—			154,992
Investments in subsidiaries	11,648,673		15,836,651		—		(27,485,324		)	—
Accrued investment income	—		2,323		310,344		—			312,667
Deferred acquisition costs and value of business acquired	—		—		890,568		—			890,568
Ceded unearned premiums	—		—		1,821,793		—			1,821,793
Premiums receivable	—		—		4,712,493		—			4,712,493
Reinsurance balances receivable	—		—		418,666		—			418,666
Unpaid losses and loss expenses recoverable	—		—		5,262,706		—			5,262,706
Receivable from investments sold	—		—		231,158		—			231,158
Goodwill and other intangible assets	—		—		2,210,266		—			2,210,266
Deferred tax asset	—		—		282,311		—			282,311
Amounts due from subsidiaries / parent	33,417		—		1,054,177		(1,087,594		)	—
Other assets	2,748		44,570		889,881		—			937,199
Total assets	$	11,696,395	$	16,770,843	$	58,788,618	$	(28,572,918	)	$	58,682,938
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities:
Unpaid losses and loss expenses	$	—	$	—	$	25,439,744	$	—		$	25,439,744
Deposit liabilities	—		—		1,168,376		—			1,168,376
Future policy benefit reserves	—		—		4,163,500		—			4,163,500
Funds withheld on GreyCastle life retrocession arrangements	—		—		914,629		—			914,629
Unearned premiums	—		—		7,043,358		—			7,043,358
Notes payable and debt	—		2,644,970		—		—			2,644,970
Reinsurance balances payable	—		—		2,117,727		—			2,117,727
Payable for investments purchased	—		—		130,060		—			130,060
Deferred tax liability	—		—		120,651		—			120,651
Amounts due to subsidiaries / parent	—		1,087,594		—		(1,087,594		)	—
Other liabilities	19,316		45,106		1,221,038		—			1,285,460
Total liabilities	$	19,316	$	3,777,670	$	42,319,083	$	(1,087,594	)	$	45,028,475
Shareholders’ Equity:
Shareholders’ equity attributable to XL Group plc	$	11,677,079	$	11,648,673	$	15,836,651	$	(27,485,324	)	$	11,677,079
Non-controlling interest in equity of consolidated subsidiaries	—		1,344,500		632,884		—			1,977,384
Total shareholders’ equity	$	11,677,079	$	12,993,173	$	16,469,535	$	(27,485,324	)	$	13,654,463
Total liabilities and shareholders’ equity	$	11,696,395	$	16,770,843	$	58,788,618	$	(28,572,918	)	$	58,682,938

	December 31, 2014
Condensed Consolidating Balance Sheet (U.S. dollars in thousands, except share data)	XL- Ireland		XL-Cayman		Other XL-Ireland Subsidiaries		Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
ASSETS
Investments:
Total investments available for sale	$	—	$	905,022	$	29,579,031	$	—		$	30,484,053
Total investments trading	—		—		1,171		—			1,171
Investments in affiliates	—		1,326		1,636,294		—			1,637,620
Other investments	—		—		1,248,439		—			1,248,439
Total investments	$	—	$	906,348	$	32,464,935	$	—		$	33,371,283
Cash and cash equivalents	22,443		42,970		2,456,401		—			2,521,814
Restricted cash	—		—		—		—			—
Investments in subsidiaries	10,195,445		13,076,044		—		(23,271,489		)	—
Accrued investment income	—		4,605		311,359		—			315,964
Deferred acquisition costs and value of business acquired	—		—		354,533		—			354,533
Ceded unearned premiums	—		—		952,525		—			952,525
Premiums receivable	—		—		2,473,736		—			2,473,736
Reinsurance balances receivable	—		—		131,519		—			131,519
Unpaid losses and loss expenses recoverable	—		—		3,429,368		—			3,429,368
Receivable from investments sold	—		—		92,762		—			92,762
Goodwill and other intangible assets	—		—		447,952		—			447,952
Deferred tax asset	—		—		204,491		—			204,491
Amounts due from subsidiaries / parent	—		—		1,010,580		(1,010,580		)	—
Other assets	3,017		46,279		701,576		—			750,872
Total assets	$	10,220,905	$	14,076,246	$	45,031,737	$	(24,282,069	)	$	45,046,819
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities:
Unpaid losses and loss expenses	$	—	$	—	$	19,353,243	$	—		$	19,353,243
Deposit liabilities	—		—		1,245,367		—			1,245,367
Future policy benefit reserves	—		—		4,707,199		—			4,707,199
Funds withheld on GreyCastle life retrocession arrangements	—		—		1,155,016		—			1,155,016
Unearned premiums	—		—		3,973,132		—			3,973,132
Notes payable and debt	—		1,662,580		—		—			1,662,580
Reinsurance balances payable	—		—		493,230		—			493,230
Payable for investments purchased	—		—		42,291		—			42,291
Deferred tax liability	—		—		66,246		—			66,246
Amounts due to subsidiaries / parent	166,782		843,798		—		(1,010,580		)	—
Other liabilities	20,372		29,923		862,454		—			912,749
Total liabilities	$	187,154	$	2,536,301	$	31,898,178	$	(1,010,580	)	$	33,611,053
Shareholders’ Equity:
Shareholders’ equity attributable to XL Group plc	$	10,033,751	$	10,195,445	$	13,076,044	$	(23,271,489	)	$	10,033,751
Non-controlling interest in equity of consolidated subsidiaries	—		1,344,500		57,515		—			1,402,015
Total shareholders’ equity	$	10,033,751	$	11,539,945	$	13,133,559	$	(23,271,489	)	$	11,435,766
Total liabilities and shareholders’ equity	$	10,220,905	$	14,076,246	$	45,031,737	$	(24,282,069	)	$	45,046,819

Condensed Income Statement [Table Text Block]

	Three Months Ended March 31, 2016
Condensed Consolidating Statement of Income and Comprehensive Income (U.S. dollars in thousands, except per share data)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Revenues:
Net premiums earned	$	—		$	—		$	2,354,610		$	—		$	2,354,610
Total net investment income	113			1,785			203,307			681			205,886
Total net realized gains (losses) on investments	—			277			90,940			1,533			92,750
Net realized and unrealized gains (losses) on derivative instruments	—			—			(3,622		)	—			(3,622		)
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	—			—			(236,080		)	—			(236,080		)
Income (loss) from investment fund affiliates	—			—			(4,579		)	—			(4,579		)
Fee income and other	—			—			8,262			—			8,262
Total revenues	$	113		$	2,062		$	2,412,838		$	2,214		$	2,417,227
Expenses:
Net losses and loss expenses incurred	$	—		$	—		$	1,382,485		$	—		$	1,382,485
Claims and policy benefits	—			—			4,937			—			4,937
Acquisition costs	—			—			403,267			—			403,267
Operating expenses	3,274			1,495			510,612			—			515,381
Exchange (gains) losses	17			(36		)	(33,800		)	—			(33,819		)
Interest expense	(6		)	35,169			17,140			—			52,303
Total expenses	$	3,285		$	36,628		$	2,284,641		$	—		$	2,324,554
Income (loss) before income tax and income (loss) from operating affiliates	$	(3,172	)	$	(34,566	)	$	128,197		$	2,214		$	92,673
Income (loss) from operating affiliates	—			—			12,650			—			12,650
Equity in net earnings (losses) of subsidiaries	24,437			94,780			—			(119,217		)	—
Provision (benefit) for income tax	(620		)	—			22,915			—			22,295
Net income (loss)	$	21,885		$	60,214		$	117,932		$	(117,003	)	$	83,028
Non-controlling interests	—			35,777			25,366			—			61,143
Net income (loss) attributable to ordinary shareholders	$	21,885		$	24,437		$	92,566		$	(117,003	)	$	21,885
Comprehensive income (loss)	$	429,826		$	432,378		$	500,507		$	(932,885	)	$	429,826

	Three Months Ended March 31, 2015
Condensed Consolidating Statement of Income and Comprehensive Income (U.S. dollars in thousands, except per share data)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Revenues:
Net premiums earned	$	—		$	—		$	1,334,000		$	—		$	1,334,000
Total net investment income	80			3,032			203,619			1,782			208,513
Total net realized gains (losses) on investments	—			1,269			52,837			(1,215		)	52,891
Net realized and unrealized gains (losses) on derivative instruments	—			(63,700		)	80,221			—			16,521
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	—			—			(229,367		)	—			(229,367		)
Income (loss) from investment fund affiliates	—			—			35,329			—			35,329
Fee income and other	—			—			4,728			—			4,728
Total revenues	$	80		$	(59,399	)	$	1,481,367		$	567		$	1,422,615
Expenses:
Net losses and loss expenses incurred	$	—		$	—		$	769,827		$	—		$	769,827
Claims and policy benefits	—			—			19,387			—			19,387
Acquisition costs	—			—			153,696			—			153,696
Operating expenses	2,762			3,000			319,894			—			325,656
Exchange (gains) losses	(262		)	33			27,619			—			27,390
Interest expense	—			37,773			13,665			—			51,438
Total expenses	$	2,500		$	40,806		$	1,304,088		$	—		$	1,347,394
Income (loss) before income tax and income (loss) from operating affiliates	$	(2,420	)	$	(100,205	)	$	177,279		$	567		$	75,221
Income (loss) from operating affiliates	—			—			22,668			—			22,668
Equity in net earnings (losses) of subsidiaries	38,485			174,426			—			(212,911		)	—
Provision (benefit) for income tax	(216		)	245			24,189			—			24,218
Net income (loss)	$	36,281		$	73,976		$	175,758		$	(212,344	)	$	73,671
Non-controlling interests	—			35,491			1,899			—			37,390
Net income (loss) attributable to ordinary shareholders	$	36,281		$	38,485		$	173,859		$	(212,344	)	$	36,281
Comprehensive income (loss)	$	256,993		$	259,197		$	394,571		$	(653,768	)	$	256,993

	Year Ended December 31, 2015
Condensed Consolidating Statement of Income and Comprehensive Income (U.S. dollars in thousands, except per share data)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Revenues:
Net premiums earned	$	—		$	—		$	8,226,425		$	—		$	8,226,425
Total net investment income	169			9,363			859,002			3,836			872,370
Total net realized gains (losses) on investments	—			13,814			197,129			(8,765		)	202,178
Net realized and unrealized gains (losses) on derivative instruments	—			12,363			40,760			—			53,123
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	—			—			(151,691		)	—			(151,691		)
Income (loss) from investment fund affiliates	—			—			73,320			—			73,320
Fee income and other	—			—			33,201			—			33,201
Total revenues	$	169		$	35,540		$	9,278,146		$	(4,929	)	$	9,308,926
Expenses:
Net losses and loss expenses incurred	$	—		$	—		$	4,766,200		$	—		$	4,766,200
Claims and policy benefits	—			—			115,997			—			115,997
Acquisition costs	—			—			1,317,448			—			1,317,448
Operating expenses	46,340			10,565			1,910,034			—			1,966,939
Exchange (gains) losses	(345		)	20			22,829			—			22,504
Extinguishment of debt	—			—			5,592			—			5,592
Interest expense	11			143,330			61,874			—			205,215
Total expenses	$	46,006		$	153,915		$	8,199,974		$	—		$	8,399,895
Income (loss) before income tax and income (loss) from operating affiliates	$	(45,837	)	$	(118,375	)	$	1,078,172		$	(4,929	)	$	909,031
Income (loss) from operating affiliates	—			—			44,740			—			44,740
Gain on sale of operating affiliate	—			—			340,407			—			340,407
Equity in net earnings (losses) of subsidiaries	1,253,609			1,449,404			—			(2,703,013		)	—
Provision (benefit) for income tax	620			245			(20,026		)	—			(19,161		)
Net income (loss)	$	1,207,152		$	1,330,784		$	1,483,345		$	(2,707,942	)	$	1,313,339
Non-controlling interests	—			77,175			29,012			—			106,187
Net income (loss) attributable to ordinary shareholders	$	1,207,152		$	1,253,609		$	1,454,333		$	(2,707,942	)	$	1,207,152
Comprehensive income (loss)	$	409,310		$	455,767		$	656,491		$	(1,112,258	)	$	409,310

	Year Ended December 31, 2014
Condensed Consolidating Statement of Income and Comprehensive Income (U.S. dollars in thousands, except per share data)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Revenues:
Net premiums earned	$	—		$	—		$	5,895,070		$	—		$	5,895,070
Total net investment income	275			20,256			889,611			8,483			918,625
Total net realized gains (losses) on investments	—			27,541			102,150			(22,229		)	107,462
Net realized and unrealized gains (losses) on derivative instruments	—			—			29,886			—			29,886
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	—			—			(488,222		)	—			(488,222		)
Income (loss) from investment fund affiliates	—			—			95,816			—			95,816
Fee income and other	—			—			43,630			—			43,630
Total revenues	$	275		$	47,797		$	6,567,941		$	(13,746	)	$	6,602,267
Expenses:
Net losses and loss expenses incurred	$	—		$	—		$	3,258,393		$	—		$	3,258,393
Claims and policy benefits	—			—			242,963			—			242,963
Acquisition costs	—			—			738,118			—			738,118
Operating expenses	9,646			13,102			1,318,567			—			1,341,315
Exchange (gains) losses	127			168			(37,863		)	—			(37,568		)
Loss on sale of life reinsurance subsidiary	—			—			666,423			—			666,423
Interest expense	5			110,323			23,778			—			134,106
Total expenses	$	9,778		$	123,593		$	6,210,379		$	—		$	6,343,750
Income (loss) before income tax and income (loss) from operating affiliates	$	(9,503	)	$	(75,796	)	$	357,562		$	(13,746	)	$	258,517
Income (loss) from operating affiliates	—			—			107,218			—			107,218
Gain on sale of operating affiliate	—			—			—			—			—
Equity in net earnings (losses) of subsidiaries	197,843			350,602			—			(548,445		)	—
Provision (benefit) for income tax	—			(212		)	97,109			—			96,897
Net income (loss)	$	188,340		$	275,018		$	367,671		$	(562,191	)	$	268,838
Non-controlling interests	—			77,175			3,323			—			80,498
Net income (loss) attributable to ordinary shareholders	$	188,340		$	197,843		$	364,348		$	(562,191	)	$	188,340
Comprehensive income (loss)	$	936,141		$	945,644		$	1,112,149		$	(2,057,793	)	$	936,141

	Year Ended December 31, 2013
Condensed Consolidating Statement of Income and Comprehensive Income (U.S. dollars in thousands, except per share data)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Revenues:
Net premiums earned	$	—		$	—		$	6,309,521		$	—		$	6,309,521
Total net investment income	24			21,994			917,993			17,705			957,716
Total net realized gains (losses) on investments	—			15,555			71,387			835			87,777
Net realized and unrealized gains (losses) on derivative instruments	—			—			7,798			—			7,798
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	—			—			—			—			—
Income (loss) from investment fund affiliates	—			3			138,388			—			138,391
Fee income and other	—			—			40,031			—			40,031
Total revenues	$	24		$	37,552		$	7,485,118		$	18,540		$	7,541,234
Expenses:
Net losses and loss expenses incurred	$	—		$	—		$	3,731,464		$	—		$	3,731,464
Claims and policy benefits	—			—			465,702			—			465,702
Acquisition costs	—			—			909,323			—			909,323
Operating expenses	11,699			12,051			1,189,428			—			1,213,178
Exchange (gains) losses	243			86			(28,572		)	—			(28,243		)
Interest expense	2			98,011			57,449			—			155,462
Total expenses	$	11,944		$	110,148		$	6,324,794		$	—		$	6,446,886
Income (loss) before income tax and income (loss) from operating affiliates	$	(11,920	)	$	(72,596	)	$	1,160,324		$	18,540		$	1,094,348
Income (loss) from operating affiliates	—			—			119,804			—			119,804
Gain on sale of operating affiliate	—			—			—			—			—
Equity in net earnings (losses) of subsidiaries	1,071,836			1,226,815			—			(2,298,651		)	—
Provision (benefit) for income tax	—			4,991			72,514			—			77,505
Net income (loss)	$	1,059,916		$	1,149,228		$	1,207,614		$	(2,280,111	)	$	1,136,647
Non-controlling interests	—			77,392			(661		)	—			76,731
Net income (loss) attributable to ordinary shareholders	$	1,059,916		$	1,071,836		$	1,208,275		$	(2,280,111	)	$	1,059,916
Comprehensive income (loss)	$	276,553		$	288,473		$	424,912		$	(713,385	)	$	276,553

Condensed Cash Flow Statement [Table Text Block]

	Three Months Ended March 31, 2016
Condensed Consolidating Statement of Cash Flows (U.S. dollars in thousands)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Cash flows provided by (used in) operating activities:
Net cash provided by (used in) operating activities	$	410,395		$	(48,205	)	$	(533,303	)	$	—		$	(171,113	)
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	132,687		$	3,815,844		$	(176,454	)	$	3,772,077
Proceeds from redemption of fixed maturities and short-term investments	—			26,181			923,040			—			949,221
Proceeds from sale of equity securities	—			—			62,895			—			62,895
Purchases of fixed maturities and short-term investments	—			(190,119		)	(4,312,014		)	176,454			(4,325,679		)
Purchases of equity securities	—			—			(55,411		)	—			(55,411		)
Proceeds from sale of affiliates	—			—			41,538			—			41,538
Purchases of affiliates	—			—			(247,049		)	—			(247,049		)
Purchase of Allied International Holdings, Inc., net of cash acquired	—			—			(69,745		)	—			(69,745		)
Change in restricted cash	—			—			(6,027		)	—			(6,027		)
Other, net	—			—			82,141			—			82,141
Net cash provided by (used in) investing activities	$	—		$	(31,251	)	$	235,212		$	—		$	203,961
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	491		$	—		$	—		$	—		$	491
Buybacks of ordinary shares	(355,901		)	—			—			—			(355,901		)
Dividends paid on ordinary shares	(57,861		)	—			—			—			(57,861		)
Distributions to non-controlling interests	—			(3,077		)	(24,780		)	—			(27,857		)
Contributions from non-controlling interests	—			—			883			—			883
Deposit liabilities	—			—			(8,546		)	—			(8,546		)
Net cash provided by (used in) financing activities	$	(413,271	)	$	(3,077	)	$	(32,443	)	$	—		$	(448,791	)
Effects of exchange rate changes on foreign currency cash	—			—			(19,396		)	—			(19,396		)
Increase (decrease) in cash and cash equivalents	$	(2,876	)	$	(82,533	)	$	(349,930	)	$	—		$	(435,339	)
Cash and cash equivalents – beginning of period	11,557			369,997			2,874,682			—			3,256,236
Cash and cash equivalents – end of period	$	8,681		$	287,464		$	2,524,752		$	—		$	2,820,897

	Three Months Ended March 31, 2015
Condensed Consolidating Statement of Cash Flows (U.S. dollars in thousands)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Cash flows provided by (used in) operating activities:
Net cash provided by (used in) operating activities	$	(31,120	)	$	134,448		$	41,318		$	(109,668	)	$	34,978
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	201,638		$	1,510,135		$	(237,832	)	$	1,473,941
Proceeds from redemption of fixed maturities and short-term investments	—			92,336			961,403			—			1,053,739
Proceeds from sale of equity securities	—			—			189,473			—			189,473
Purchases of fixed maturities and short-term investments	—			(453,628		)	(2,619,508		)	237,832			(2,835,304		)
Purchases of equity securities	—			—			(94,141		)	—			(94,141		)
Proceeds from sale of affiliates	—			—			77,916			—			77,916
Purchases of affiliates	—			—			(29,037		)	—			(29,037		)
Returns of capital from subsidiaries	65,037			—			—			(65,037		)	—
Other, net	—			—			(32,141		)	—			(32,141		)
Net cash provided by (used in) investing activities	$	65,037		$	(159,654	)	$	(35,900	)	$	(65,037	)	$	(195,554	)
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	1,772		$	—		$	—		$	—		$	1,772
Buybacks of ordinary shares	(1,966		)	—			—			—			(1,966		)
Dividends paid on ordinary shares	(40,922		)	(109,668		)	—			109,668			(40,922		)
Return of capital	—			(65,037		)	—			65,037			—
Distributions to non-controlling interests	—			(2,995		)	(4,177		)	—			(7,172		)
Contributions from non-controlling interests	—			—			2,569			—			2,569
Proceeds from issuance of debt	—			980,600			—			—			980,600
Deposit liabilities	—			—			(38,788		)	—			(38,788		)
Net cash provided by (used in) financing activities	$	(41,116	)	$	802,900		$	(40,396	)	$	174,705		$	896,093
Effects of exchange rate changes on foreign currency cash	—			—			(47,397		)	—			(47,397		)
Increase (decrease) in cash and cash equivalents	$	(7,199	)	$	777,694		$	(82,375	)	$	—		$	688,120
Cash and cash equivalents – beginning of period	22,443			42,970			2,456,401			—			2,521,814
Cash and cash equivalents – end of period	$	15,244		$	820,664		$	2,374,026		$	—		$	3,209,934

	Year Ended December 31, 2015
Condensed Consolidating Statement of Cash Flows (U.S. dollars in thousands)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Cash flows provided by (used in) operating activities:
Net cash provided by (used in) operating activities	$	561,468		$	148,850		$	669,515		$	(764,277	)	$	615,556
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	1,482,875		$	15,745,247		$	(359,894	)	$	16,868,228
Proceeds from redemption of fixed maturities and short-term investments	—			188,788			3,562,386			—			3,751,174
Proceeds from sale of equity securities	—			—			664,735			—			664,735
Purchases of fixed maturities and short-term investments	—			(1,296,980		)	(18,780,978		)	359,894			(19,718,064		)
Purchases of equity securities	—			—			(567,334		)	—			(567,334		)
Proceeds from sale of affiliates	—			—			188,023			—			188,023
Purchases of affiliates	—			—			(280,856		)	—			(280,856		)
Purchase of Catlin Group Limited, net of acquired cash	(2,287,579		)	(2,317,699		)	1,267,564			2,317,699			(1,020,015		)
Proceeds from sale of subsidiary	2,317,699			—			—			(2,317,699		)	—
Proceeds from sale of ARX Holding Corp.	—			—			560,552			—			560,552
Returns of capital from subsidiaries	65,037			2,047,000			—			(2,112,037		)	—
Change in restricted cash	—			—			(154,992		)	—			(154,992		)
Other, net	—			—			(155,019		)	—			(155,019		)
Net cash provided by (used in) investing activities	$	95,157		$	103,984		$	2,049,328		$	(2,112,037	)	$	136,432
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	9,976		$	—		$	—		$	—		$	9,976
Buybacks of ordinary shares	(468,971		)	—			—			—			(468,971		)
Dividends paid on ordinary shares	(208,516		)	(764,277		)	—			764,277			(208,516		)
Return of capital	—			(65,037		)	(2,047,000		)	2,112,037			—
Distributions to non-controlling interests	—			(77,093		)	(40,590		)	—			(117,683		)
Contributions from non-controlling interests	—			—			23,610			—			23,610
Proceeds from issuance of debt	—			980,600			—			—			980,600
Repayment of debt	—			—			(87,447		)	—			(87,447		)
Deposit liabilities	—			—			(84,758		)	—			(84,758		)
Net cash provided by (used in) financing activities	$	(667,511	)	$	74,193		$	(2,236,185	)	$	2,876,314		$	46,811
Effects of exchange rate changes on foreign currency cash	—			—			(64,377		)	—			(64,377		)
Increase (decrease) in cash and cash equivalents	$	(10,886	)	$	327,027		$	418,281		$	—		$	734,422
Cash and cash equivalents – beginning of period	22,443			42,970			2,456,401			—			2,521,814
Cash and cash equivalents – end of period	$	11,557		$	369,997		$	2,874,682		$	—		$	3,256,236

	Year Ended December 31, 2014
Condensed Consolidating Statement of Cash Flows (U.S. dollars in thousands)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Cash flows provided by (used in) operating activities:
Net cash provided by (used in) operating activities	$	895,854		$	518,715		$	407,136		$	(858,521	)	$	963,184
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	574,673		$	4,793,978		$	(472,539	)	$	4,896,112
Proceeds from redemption of fixed maturities and short-term investments	—			351,737			3,250,056			—			3,601,793
Proceeds from sale of equity securities	—			—			571,410			—			571,410
Purchases of fixed maturities and short-term investments	—			(307,830		)	(7,322,967		)	472,539			(7,158,258		)
Purchases of equity securities	—			—			(445,504		)	—			(445,504		)
Proceeds from sale of affiliates	—			—			240,785			—			240,785
Purchases of affiliates	—			—			(371,226		)	—			(371,226		)
Proceeds from sale of subsidiary	—			—			570,000			—			570,000
Returns of capital from subsidiaries	79,086			482,570			—			(561,656		)	—
Change in restricted cash	—			—			—			—			—
Other, net	—			1,920			(195,411		)	—			(193,491		)
Net cash provided by (used in) investing activities	$	79,086		$	1,103,070		$	1,091,121		$	(561,656	)	$	1,711,621
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	6,367		$	—		$	—		$	—		$	6,367
Buybacks of ordinary shares	(801,953		)	—			—			—			(801,953		)
Dividends paid on ordinary shares	(169,620		)	(858,521		)	—			858,521			(169,620		)
Return of capital	—			(79,086		)	(482,570		)	561,656			—
Distributions to non-controlling interests	—			(77,002		)	(1,463		)	—			(78,465		)
Contributions from non-controlling interests	—			—			48,261			—			48,261
Repayment of debt	—			(600,000		)	—			—			(600,000		)
Deposit liabilities	—			—			(268,298		)	—			(268,298		)
Net cash provided by (used in) financing activities	$	(965,206	)	$	(1,614,609	)	$	(704,070	)	$	1,420,177		$	(1,863,708	)
Effects of exchange rate changes on foreign currency cash	—			—			(90,115		)	—			(90,115		)
Increase (decrease) in cash and cash equivalents	$	9,734		$	7,176		$	704,072		$	—		$	720,982
Cash and cash equivalents – beginning of period	12,709			35,794			1,752,329			—			1,800,832
Cash and cash equivalents – end of period	$	22,443		$	42,970		$	2,456,401		$	—		$	2,521,814

	Year Ended December 31, 2013
Condensed Consolidating Statement of Cash Flows (U.S. dollars in thousands)	XL- Ireland			XL-Cayman			Other XL-Ireland Subsidiaries			Consolidating Adjustments and Eliminations			XL-Ireland Consolidated
Cash flows provided by (used in) operating activities:
Net cash provided by (used in) operating activities	$	740,308		$	(175,056	)	$	832,444		$	(617,719	)	$	779,977
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	$	—		$	254,053		$	4,282,227		$	(194,851	)	$	4,341,429
Proceeds from redemption of fixed maturities and short-term investments	—			203,054			3,805,279			—			4,008,333
Proceeds from sale of equity securities	—			—			245,538			—			245,538
Purchases of fixed maturities and short-term investments	—			(828,603		)	(8,510,221		)	194,851			(9,143,973		)
Purchases of equity securities	—			—			(534,356		)	—			(534,356		)
Proceeds from sale of affiliates	—			—			190,954			—			190,954
Purchases of affiliates	—			—			(353,678		)	—			(353,678		)
Returns of capital from subsidiaries	84,589			546,912			—			(631,501		)	—
Change in restricted cash	—			—			—			—			—
Other, net	—			3,753			44,138			—			47,891
Net cash provided by (used in) investing activities	$	84,589		$	179,169		$	(830,119	)	$	(631,501	)	$	(1,197,862	)
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	$	12,623		$	—		$	—		$	—		$	12,623
Buybacks of ordinary shares	(675,617		)	—			—			—			(675,617		)
Dividends paid on ordinary shares	(160,155		)	(617,719		)	—			617,719			(160,155		)
Return of capital	—			(84,589		)	(546,912		)	631,501			—
Distributions to non-controlling interests	—			(77,670		)	—			—			(77,670		)
Contributions from non-controlling interests	—			—			7,747			—			7,747
Proceeds from issuance of debt	—			592,615			—			—			592,615
Deposit liabilities	—			—			(94,386		)	—			(94,386		)
Net cash provided by (used in) financing activities	$	(823,149	)	$	(187,363	)	$	(633,551	)	$	1,249,220		$	(394,843	)
Effects of exchange rate changes on foreign currency cash	—			—			(4,818		)	—			(4,818		)
Increase (decrease) in cash and cash equivalents	$	1,748		$	(183,250	)	$	(636,044	)	$	—		$	(817,546	)
Cash and cash equivalents – beginning of period	10,961			219,044			2,388,373			—			2,618,378
Cash and cash equivalents – end of period	$	12,709		$	35,794		$	1,752,329		$	—		$	1,800,832