Guarantor Financial Information Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2016		Dec. 31, 2015		Sep. 30, 2015	Dec. 31, 2014
ASSETS
Total investments available for sale	$ 33,625,072		$ 33,753,898
Total investments trading	1,633,051		1,296,029
Investments in affiliates	2,118,489		1,708,899
Other investments	1,260,938		1,433,057
Investments	38,637,550		38,191,883
Cash and cash equivalents	3,393,277		3,256,236		$ 3,340,070	$ 2,521,814
Restricted cash	150,118		154,992
Investments in subsidiaries	0		0
Accrued investment income	285,504		312,667
Deferred acquisition costs and value of business acquired	989,733		890,568
Ceded unearned premiums	1,917,127		1,821,793
Premiums receivable	5,925,969		4,712,493
Reinsurance balances receivable	524,343		418,666
Unpaid losses and loss expenses recoverable	5,481,882		5,262,706
Receivable from investments sold	105,781		231,158
Goodwill and other intangible assets	2,234,071		2,210,266
Deferred tax asset	219,905		282,311
Amounts due from subsidiaries/parent	0		0
Other assets	906,790		937,199
Total assets	60,772,050		58,682,938
Liabilities:
Unpaid losses and loss expenses	26,170,383		25,439,744
Deposit liabilities	1,138,789		1,168,376
Future policy benefit reserves	3,721,451		4,163,500
Funds withheld on GreyCastle life retrocession arrangements	1,283,055		914,629
Unearned premiums	7,724,957		7,043,358
Notes payable and debt	2,647,000		2,644,970
Reinsurance balances payable	2,698,185		2,117,727
Payable for investments purchased	370,456		130,060
Deferred tax liability	108,996		120,651
Amounts due to subsidiaries/parent	0		0
Other liabilities	1,315,898		1,285,460
Total liabilities	47,179,170		45,028,475
Shareholders' Equity:
Shareholders' equity attributable to XL Group Ltd	11,612,166		11,677,079
Non-controlling interest in equity of consolidated subsidiaries	1,980,714		1,977,384
Total shareholders' equity	13,592,880		13,654,463		13,900,508
Total liabilities and shareholders' equity	60,772,050		58,682,938
Consolidating Adjustments and Eliminations
ASSETS
Total investments available for sale	0		0
Total investments trading	0		0
Investments in affiliates	0		0
Other investments	0		0
Investments	0		0
Cash and cash equivalents	0		0		0	(43,293)
Restricted cash	0		0
Investments in subsidiaries	(26,714,814)		(27,485,324)
Accrued investment income	(65)		0
Deferred acquisition costs and value of business acquired	0		0
Ceded unearned premiums	0		0
Premiums receivable	0		0
Reinsurance balances receivable	0		0
Unpaid losses and loss expenses recoverable	0		0
Receivable from investments sold	0		0
Goodwill and other intangible assets	0		0
Deferred tax asset	0		0
Amounts due from subsidiaries/parent	(369,835)		(1,087,594)
Other assets	0		0
Total assets	(27,084,714)		(28,572,918)
Liabilities:
Unpaid losses and loss expenses	0		0
Deposit liabilities	0		0
Future policy benefit reserves	0		0
Funds withheld on GreyCastle life retrocession arrangements	0		0
Unearned premiums	0		0
Notes payable and debt	0		0
Reinsurance balances payable	0		0
Payable for investments purchased	0		0
Deferred tax liability	0		0
Amounts due to subsidiaries/parent	(369,835)		(1,087,594)
Other liabilities	0		0
Total liabilities	(369,835)		(1,087,594)
Shareholders' Equity:
Shareholders' equity attributable to XL Group Ltd	(26,714,814)		(27,485,324)
Non-controlling interest in equity of consolidated subsidiaries	(65)		0
Total shareholders' equity	(26,714,879)		(27,485,324)
Total liabilities and shareholders' equity	(27,084,714)		(28,572,918)
XL- Bermuda/Ireland
ASSETS
Total investments available for sale	0	[1]	0
Total investments trading	0	[1]	0
Investments in affiliates	0	[1]	0
Other investments	0	[1]	0
Investments	0	[1]	0
Cash and cash equivalents	12,875	[1]	11,557	[1]	3,557	22,443
Restricted cash	0	[1]	0
Investments in subsidiaries	11,791,273	[1]	11,648,673
Accrued investment income	65	[1]	0
Deferred acquisition costs and value of business acquired	0	[1]	0
Ceded unearned premiums	0	[1]	0
Premiums receivable	0	[1]	0
Reinsurance balances receivable	0	[1]	0
Unpaid losses and loss expenses recoverable	0	[1]	0
Receivable from investments sold	0	[1]	0
Goodwill and other intangible assets	0	[1]	0
Deferred tax asset	0	[1]	0
Amounts due from subsidiaries/parent	0	[1]	33,417
Other assets	2,294	[1]	2,748
Total assets	11,806,507	[1]	11,696,395
Liabilities:
Unpaid losses and loss expenses	0	[1]	0
Deposit liabilities	0	[1]	0
Future policy benefit reserves	0	[1]	0
Funds withheld on GreyCastle life retrocession arrangements	0	[1]	0
Unearned premiums	0	[1]	0
Notes payable and debt	0	[1]	0
Reinsurance balances payable	0	[1]	0
Payable for investments purchased	0	[1]	0
Deferred tax liability	0	[1]	0
Amounts due to subsidiaries/parent	173,821	[1]	0
Other liabilities	20,520	[1]	19,316
Total liabilities	194,341	[1]	19,316
Shareholders' Equity:
Shareholders' equity attributable to XL Group Ltd	11,612,166	[1]	11,677,079
Non-controlling interest in equity of consolidated subsidiaries	0	[1]	0
Total shareholders' equity	11,612,166	[1]	11,677,079
Total liabilities and shareholders' equity	11,806,507	[1]	11,696,395
XL-Cayman
ASSETS
Total investments available for sale	676,964		516,425
Total investments trading	0		0
Investments in affiliates	0		0
Other investments	897		877
Investments	677,861		517,302
Cash and cash equivalents	14,495		369,997		197,682	86,263
Restricted cash	0		0
Investments in subsidiaries	14,923,541		15,836,651
Accrued investment income	3,350		2,323
Deferred acquisition costs and value of business acquired	0		0
Ceded unearned premiums	0		0
Premiums receivable	0		0
Reinsurance balances receivable	0		0
Unpaid losses and loss expenses recoverable	0		0
Receivable from investments sold	0		0
Goodwill and other intangible assets	0		0
Deferred tax asset	0		0
Amounts due from subsidiaries/parent	196,014		0
Other assets	40,938		44,570
Total assets	15,856,199		16,770,843
Liabilities:
Unpaid losses and loss expenses	0		0
Deposit liabilities	0		0
Future policy benefit reserves	0		0
Funds withheld on GreyCastle life retrocession arrangements	0		0
Unearned premiums	0		0
Notes payable and debt	2,647,000		2,644,970
Reinsurance balances payable	0		0
Payable for investments purchased	0		0
Deferred tax liability	0		0
Amounts due to subsidiaries/parent	0		1,087,594
Other liabilities	73,426		45,106
Total liabilities	2,720,426		3,777,670
Shareholders' Equity:
Shareholders' equity attributable to XL Group Ltd	11,791,273		11,648,673
Non-controlling interest in equity of consolidated subsidiaries	1,344,500		1,344,500
Total shareholders' equity	13,135,773		12,993,173
Total liabilities and shareholders' equity	15,856,199		16,770,843
Other XL Subsidiaries
ASSETS
Total investments available for sale	32,948,108		33,237,473
Total investments trading	1,633,051		1,296,029
Investments in affiliates	2,118,489		1,708,899
Other investments	1,260,041		1,432,180
Investments	37,959,689		37,674,581
Cash and cash equivalents	3,365,907		2,874,682		$ 3,138,831	$ 2,456,401
Restricted cash	150,118		154,992
Investments in subsidiaries	0		0
Accrued investment income	282,154		310,344
Deferred acquisition costs and value of business acquired	989,733		890,568
Ceded unearned premiums	1,917,127		1,821,793
Premiums receivable	5,925,969		4,712,493
Reinsurance balances receivable	524,343		418,666
Unpaid losses and loss expenses recoverable	5,481,882		5,262,706
Receivable from investments sold	105,781		231,158
Goodwill and other intangible assets	2,234,071		2,210,266
Deferred tax asset	219,905		282,311
Amounts due from subsidiaries/parent	173,821		1,054,177
Other assets	863,558		889,881
Total assets	60,194,058		58,788,618
Liabilities:
Unpaid losses and loss expenses	26,170,383		25,439,744
Deposit liabilities	1,138,789		1,168,376
Future policy benefit reserves	3,721,451		4,163,500
Funds withheld on GreyCastle life retrocession arrangements	1,283,055		914,629
Unearned premiums	7,724,957		7,043,358
Notes payable and debt	0		0
Reinsurance balances payable	2,698,185		2,117,727
Payable for investments purchased	370,456		130,060
Deferred tax liability	108,996		120,651
Amounts due to subsidiaries/parent	196,014		0
Other liabilities	1,221,952		1,221,038
Total liabilities	44,634,238		42,319,083
Shareholders' Equity:
Shareholders' equity attributable to XL Group Ltd	14,923,541		15,836,651
Non-controlling interest in equity of consolidated subsidiaries	636,279		632,884
Total shareholders' equity	15,559,820		16,469,535
Total liabilities and shareholders' equity	$ 60,194,058		$ 58,788,618

[1] Results for the period include XL-Ireland, which prior to the Redomestication was the ultimate parent and is now in liquidation proceedings as outlined in Note 1, "Basis of Preparation and Consolidation." The Company expects the net assets of XL-Ireland to ultimately be distributed to XL-Bermuda upon completion of the liquidation.