XL (XLGLF) 10-K 26 Feb 16 2015 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Feb. 23, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	XL GROUP PLC
Entity Central Index Key	875,159
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		291,794,761
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 11.2

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Investments:
Fixed maturities, at fair value (amortized cost: 2015, $31,517,654; 2014, $27,728,771)		$ 32,257,589	$ 29,359,034
Equity securities, at fair value (cost: 2015, $834,079; 2014, $763,833)		878,919	868,292
Short-term investments, at fair value (amortized cost: 2015, $618,851; 2014, $257,221)		617,390	256,727
Total investments available for sale		33,753,898	30,484,053
Fixed maturities, at fair value (amortized cost: 2015, $1,263,609; 2014, $1,180)		1,235,699	1,171
Short-term investments, at fair value (amortized cost: 2015, $60,176; 2014, nil)		60,330	0
Total investments trading		1,296,029	1,171
Investments in affiliates		1,708,899	1,637,620
Other investments		1,433,057	1,248,439
Total investments		38,191,883	33,371,283
Cash and cash equivalents		3,256,236	2,521,814
Restricted cash		154,992	0
Accrued investment income		312,667	315,964
Deferred acquisition costs and value of business acquired		890,568	354,533
Ceded unearned premiums		1,821,793	952,525
Premiums receivable		4,712,493	2,473,736
Reinsurance balances receivable		418,666	131,519
Unpaid losses and loss expenses recoverable		5,262,706	3,429,368
Receivable from investments sold		231,158	92,762
Goodwill and other intangible assets		2,210,266	447,952
Deferred tax asset		282,311	204,491
Other assets		937,199	750,872
Total assets		58,682,938	45,046,819
Liabilities:
Unpaid losses and loss expenses		25,439,744	19,353,243
Deposit liabilities		1,168,376	1,245,367
Future policy benefit reserves		4,163,500	4,707,199
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)		914,629	1,155,016
Unearned premiums		7,043,358	3,973,132
Notes payable and debt	[1]	2,644,970	1,662,580
Reinsurance balances payable		2,117,727	493,230
Payable for investments purchased		130,060	42,291
Deferred tax liability		120,651	66,246
Other liabilities		1,285,460	912,749
Total liabilities		$ 45,028,475	$ 33,611,053
Commitments and Contingencies
Shareholders' Equity:
Ordinary shares, 999,990,000 authorized, par value $0.01; issued and outstanding (2015, 294,745,045; 2014, 255,182,955)		$ 2,947	$ 2,552
Additional paid in capital		8,910,167	7,359,102
Accumulated other comprehensive income		686,616	1,484,458
Retained earnings		2,077,349	1,187,639
Shareholders' equity attributable to XL Group plc		11,677,079	10,033,751
Non-controlling interest in equity of consolidated subsidiaries		1,977,384	1,402,015
Total shareholders' equity		13,654,463	11,435,766
Total liabilities and shareholders' equity		$ 58,682,938	$ 45,046,819
[1]	"In Use/Outstanding" data represent December 31, 2015 and December 31, 2014 accreted values.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amortized cost of fixed maturities, available for sale	$ 31,517,654	$ 27,728,771
Cost of equity securities, available for sale	834,079	763,833
Amortized cost of short-term investments, available for sale	618,851	257,221
Amortized cost of fixed maturities, trading	1,263,609	1,180
Amortized cost of short term investments, trading	60,176	0
Reinsurance recoverable from GCLR	$ 3,719,131	$ 4,265,678
Ordinary shares, shares authorized (in shares)	999,990,000	999,990,000
Ordinary shares, par value (in dollars per share)	$ 0.01	$ 0.01
Ordinary shares, shares issued (in shares)	294,745,045	255,182,955
Ordinary shares, shares outstanding (in shares)	294,745,045	255,182,955	278,253,000

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Revenues:
Net premiums earned	$ 8,226,425		$ 5,895,070	$ 6,309,521
Net investment income	872,370		918,625	957,716
Realized investment gains (losses):
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	202,178		107,462	87,777
Net realized and unrealized gains (losses) on derivative instruments	53,123		29,886	7,798
Income (loss) from investment fund affiliates	73,320		95,816	138,391
Fee income and other	33,201		43,630	40,031
Total revenues	9,308,926		6,602,267	7,541,234
Expenses:
Net losses and loss expenses incurred	4,766,200		3,258,393	3,731,464
Claims and policy benefits	115,997		242,963	465,702
Acquisition costs	1,317,448	[1]	738,118	909,323
Operating expenses	1,966,939		1,341,315	1,213,178
Foreign exchange (gains) losses	22,504		(37,568)	(28,243)
Loss on sale of life reinsurance subsidiary	0		666,423	0
Extinguishment of debt	5,592		0	0
Interest expense	205,215		134,106	155,462
Total expenses	8,399,895		6,343,750	6,446,886
Income (loss) before income tax and income (loss) from operating affiliates	909,031		258,517	1,094,348
Income (loss) from operating affiliates	44,740		107,218	119,804
Gain on sale of operating affiliate	340,407		0	0
Provision (benefit) for income tax	(19,161)		96,897	77,505
Net income (loss)	1,313,339		268,838	1,136,647
Non-controlling interests	106,187		80,498	76,731
Net income (loss) attributable to ordinary shareholders	$ 1,207,152		$ 188,340	$ 1,059,916
Weighted average ordinary shares and ordinary share equivalents outstanding - basic (in shares)	286,194		267,103	287,801
Weighted average ordinary shares and ordinary share equivalents outstanding - diluted (in shares)	290,999		271,527	292,069
Earnings (loss) per ordinary share and ordinary share equivalent - basic (in dollars per share)	$ 4.22		$ 0.71	$ 3.68
Earnings (loss) per ordinary share and ordinary share equivalent - diluted (in dollars per share)	$ 4.15		$ 0.69	$ 3.63
Exclude Life Funds Withheld Assets [Member]
Revenues:
Net investment income	$ 684,881		$ 789,050	$ 957,716
Realized investment gains (losses):
Net realized gains (losses) on investments sold	102,957		158,733	104,076
Other-than-temporary impairments (OTTI) on investments	(81,987)		(33,508)	(10,266)
OTTI on investments transferred to (from) other comprehensive income	(973)		(2,234)	(6,033)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	19,997		122,991	87,777
Life Funds Withheld Assets [Member]
Revenues:
Net investment income	187,489		129,575	0
Realized investment gains (losses):
Net realized gains (losses) on investments sold	223,272		5,067	0
Other-than-temporary impairments (OTTI) on investments	(13,357)		(20,587)	0
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(27,734)		(9)	0
Net realized and unrealized gains (losses) on derivative instruments	$ (151,691)		$ (488,222)	$ 0
[1]	The Company has reflected the amortization of certain fair value adjustments recorded in conjunction with the Catlin Acquisition within the respective segments.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income (loss) attributable to ordinary shareholders	$ 1,207,152	$ 188,340	$ 1,059,916
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax	0	424,861	0
Cumulative adjustments recorded to value of future policy benefit reserves, amount	170,688	(400,456)	(44,660)
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	(6,074)	35,143	26,637
Change in OTTI losses recognized in other comprehensive income, net of tax	18,545	13,143	32,181
Change in underfunded pension liability	(3,852)	(7,550)	7,653
Change in value of cash flow hedge	(200)	255	439
Foreign currency translation adjustments	(25,315)	(25,729)	(54,858)
Comprehensive income (loss)	409,310	936,141	276,553
Exclude Life Funds Withheld Assets [Member]
Change in net unrealized gains (losses) on investments, net of tax	(530,030)	434,051	(750,755)
Life Funds Withheld Assets [Member]
Change in net unrealized gains (losses) on investments, net of tax	$ (421,604)	$ 274,083	$ 0

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Ordinary shares	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)	Non-controlling Interest in Equity of Consolidated Subsidiaries	Exclude Life Funds Withheld Assets [Member]	Exclude Life Funds Withheld Assets [Member]Accumulated Other Comprehensive Income (Loss)	Life Funds Withheld Assets [Member]	Life Funds Withheld Assets [Member]Accumulated Other Comprehensive Income (Loss)
Noncontrolling Interest, Increase From Contributions						$ 7,747
Balance, beginning of year at Dec. 31, 2012		$ 2,987	$ 8,584,752	$ 1,520,020	$ 402,319	1,346,325
Issuance of ordinary shares		13	29
Buybacks of ordinary shares		(226)	(639,292)		(36,098)
Exercise of stock options		9
Exercise of stock options, net of tax			12,614
Share based compensation expense			35,997		0
Change in net unrealized gains (losses) on investments, net of tax							$ (750,755)	$ (750,755)	$ 0	$ 0
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax	$ 0			0
Cumulative adjustments recorded to value of future policy benefit reserves, amount	(44,660)			(44,660)
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	26,637			26,637
Change in OTTI losses recognized in other comprehensive income, net of tax	32,181			32,181
Change in underfunded pension liability	7,653			7,653
Change in value of cash flow hedge	439			439
Foreign currency translation adjustments	(54,858)			(54,858)
Net income (loss) attributable to ordinary shareholders	1,059,916				1,059,916
Dividends on ordinary shares					(162,044)
Non-controlling interests - contributions						0
Non-controlling interests - distributions						(37)
Non-controlling interests						(500)
Non-controlling interest share in change in accumulated other comprehensive income (loss)						(29)
Non-controlling interests - deconsolidation						(1,841)
Balance, end of year at Dec. 31, 2013	11,349,298	2,783	7,994,100	736,657	1,264,093	1,351,665
Noncontrolling Interest, Increase From Contributions						48,261
Issuance of ordinary shares		12	27
Buybacks of ordinary shares		(247)	(708,993)		(92,713)
Exercise of stock options		4
Exercise of stock options, net of tax			6,363
Share based compensation expense			67,605		0
Change in net unrealized gains (losses) on investments, net of tax							434,051	434,051	274,083	274,083
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax	424,861			424,861
Cumulative adjustments recorded to value of future policy benefit reserves, amount	(400,456)			(400,456)
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	35,143			35,143
Change in OTTI losses recognized in other comprehensive income, net of tax	13,143			13,143
Change in underfunded pension liability	(7,550)			(7,550)
Change in value of cash flow hedge	255			255
Foreign currency translation adjustments	(25,729)			(25,729)
Net income (loss) attributable to ordinary shareholders	188,340				188,340
Dividends on ordinary shares					(172,081)
Non-controlling interests - contributions						0
Non-controlling interests - distributions						(1,666)
Non-controlling interests						3,755
Non-controlling interest share in change in accumulated other comprehensive income (loss)						0
Non-controlling interests - deconsolidation						0
Balance, end of year at Dec. 31, 2014	11,435,766	2,552	7,359,102	1,484,458	1,187,639	1,402,015
Noncontrolling Interest, Increase From Contributions						23,610
Issuance of ordinary shares		515	1,851,046
Buybacks of ordinary shares		(125)	(370,395)		(98,451)
Exercise of stock options		5
Exercise of stock options, net of tax			9,972
Share based compensation expense			60,442		(7,177)
Change in net unrealized gains (losses) on investments, net of tax							$ (530,030)	$ (530,030)	$ (421,604)	$ (421,604)
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax	0			0
Cumulative adjustments recorded to value of future policy benefit reserves, amount	170,688			170,688
Change in net unrealized gains (losses) on affiliate and other investments, net of tax	(6,074)			(6,074)
Change in OTTI losses recognized in other comprehensive income, net of tax	18,545			18,545
Change in underfunded pension liability	(3,852)			(3,852)
Change in value of cash flow hedge	(200)			(200)
Foreign currency translation adjustments	(25,315)			(25,315)
Net income (loss) attributable to ordinary shareholders	1,207,152				1,207,152
Dividends on ordinary shares					(211,814)
Non-controlling interests - contributions						562,285
Non-controlling interests - distributions						(19,001)
Non-controlling interests						7,466
Non-controlling interest share in change in accumulated other comprehensive income (loss)						1,009
Non-controlling interests - deconsolidation						0
Balance, end of year at Dec. 31, 2015	$ 13,654,463	$ 2,947	$ 8,910,167	$ 686,616	$ 2,077,349	$ 1,977,384

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows provided by (used in) operating activities:
Net income (loss)	$ 1,313,339	$ 268,838	$ 1,136,647
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Net realized (gains) losses on investments	(202,178)	(107,462)	(87,777)
Net realized and unrealized (gains) losses on derivative instruments	(53,123)	(29,886)	(7,798)
Amortization of premiums (discounts) on fixed maturities	194,824	153,849	166,621
(Income) loss from investment and operating affiliates	(46,072)	(129,915)	(229,386)
Loss on sale of life reinsurance subsidiary	0	666,423	0
Gain on sale of operating affiliate	(340,407)	0	0
Share based compensation	74,431	81,287	46,489
Depreciation and amortization	92,313	56,118	56,229
Accretion of deposit liabilities	43,633	11,195	47,256
Changes in:
Unpaid losses and loss expenses	(211,831)	(427,528)	(88,636)
Future policy benefit reserves	(278,818)	(229,204)	(164,923)
Funds withheld on life retrocession agreements, net	(210,943)	(218,144)	0
Unearned premiums	(528,214)	253,396	65,279
Premiums receivable	156,168	15,248	(27,334)
Unpaid losses and loss expenses recoverable	(439,548)	(44,688)	(36,897)
Ceded unearned premiums	237,017	(191,242)	(196,674)
Reinsurance balances receivable	2,319	(17,736)	(60,317)
Deferred acquisition costs and value of business acquired	126,455	303,998	8,532
Reinsurance balances payable	229,205	160,916	161,132
Deferred tax asset - net	(47,924)	(33,735)	(29,230)
Derivatives	185,300	42,187	(22,324)
Other assets	17,054	33,344	(26,945)
Other liabilities	123,897	(147,744)	60,331
Other	26,968	5,447	9,702
Total adjustments	(697,783)	694,346	(356,670)
Net cash provided by (used in) operating activities	615,556	963,184	779,977
Cash flows provided by (used in) investing activities:
Proceeds from sale of fixed maturities and short-term investments	16,868,228	4,896,112	4,341,429
Proceeds from redemption of fixed maturities and short-term investments	3,751,174	3,601,793	4,008,333
Proceeds from sale of equity securities	664,735	571,410	245,538
Purchases of fixed maturities and short term investments	(19,718,064)	(7,158,258)	(9,143,973)
Purchases of equity securities	(567,334)	(445,504)	(534,356)
Proceeds from sale of affiliates	188,023	240,785	190,954
Purchases of affiliates	(280,856)	(371,226)	(353,678)
Purchase of Catlin Group Limited, net of acquired cash	(1,020,015)	0	0
Proceeds from sale of life reinsurance subsidiary	0	570,000	0
Proceeds from sale of ARX Holding Corp.	560,552	0	0
Change in restricted cash	(154,992)	0	0
Other, net	(155,019)	(193,491)	47,891
Net cash provided by (used in) investing activities	136,432	1,711,621	(1,197,862)
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options	9,976	6,367	12,623
Buybacks of ordinary shares	(468,971)	(801,953)	(675,617)
Dividends paid on ordinary shares	(208,516)	(169,620)	(160,155)
Distributions to non-controlling interests	(117,683)	(78,465)	(77,670)
Contributions from non-controlling interest	23,610	48,261	7,747
Proceeds from issuance of debt	980,600	0	592,615
Repayment of debt	(87,447)	(600,000)	0
Deposit liabilities	(84,758)	(268,298)	(94,386)
Net cash provided by (used in) financing activities	46,811	(1,863,708)	(394,843)
Effects of exchange rate changes on foreign currency cash	(64,377)	(90,115)	(4,818)
Increase (decrease) in cash and cash equivalents	734,422	720,982	(817,546)
Cash and cash equivalents – beginning of period	2,521,814	1,800,832	2,618,378
Cash and cash equivalents – end of period	3,256,236	2,521,814	1,800,832
Supplemental cash flow disclosures:
Net taxes paid	96,886	20,168	96,469
Interest paid on notes payable and debt	115,598	121,285	97,125
Life Funds Withheld Assets [Member]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Net realized (gains) losses on investments	(182,181)	15,529
Net realized and unrealized (gains) losses on derivative instruments	$ 151,691	$ 488,222	$ 0

General

General	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General XL Group plc, an Irish public limited company ("XL-Ireland"), through its operating subsidiaries (collectively, the "Company"), is a leading provider of insurance and reinsurance coverages to industrial, commercial and professional firms, insurance companies and other enterprises on a worldwide basis. Unless the context otherwise indicates, references herein to the "Company" are to, and these financial statements include the accounts of, XL-Ireland and its consolidated subsidiaries. The Company and its various subsidiaries operate globally in 29 countries, through the Company's two business segments: Insurance and Reinsurance. These segments are further discussed in Note 5, "Segment Information ." On May 1, 2015, the Company completed its acquisition (the "Catlin Acquisition") of Catlin Group Limited and its consolidated subsidiaries ("Catlin"). Catlin, through its wholly-owned subsidiaries, provided property, casualty and specialty insurance and reinsurance coverage on a worldwide basis. The Company's consolidated results of operations include those of Catlin from May 1, 2015. See Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," for additional information with respect to the acquisition of Catlin. On July 1, 2010, XL-Ireland and XLIT Ltd. (formerly XL Capital Ltd.), a Cayman Islands exempted company ("XL-Cayman") completed a redomestication transaction in which all of the ordinary shares of XL-Cayman were exchanged for all of the ordinary shares of XL-Ireland (the "Redomestication"). As a result, XL-Cayman became a wholly owned subsidiary of XL-Ireland. On July 23, 2010, the Irish High Court approved XL-Ireland’s creation of distributable reserves, subject to the completion of certain formalities under Irish Company law. These formalities were completed in early August 2010.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant accounting policies	Significant Accounting Policies (a) Basis of Preparation and Consolidation These consolidated financial statements include the accounts of the Company and all of its subsidiaries. These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). To facilitate period-to-period comparisons, certain reclassifications have been made to prior year consolidated financial statement amounts to conform to the current year presentation. There was no effect on net income from this change in presentation. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company’s most significant areas of estimation include: ▪ unpaid losses and loss expenses and unpaid losses and loss expenses recoverable; ▪ future policy benefit reserves; ▪ valuation and other-than-temporary impairments of investments; ▪ income taxes; ▪ reinsurance premium estimates; and ▪ carrying value of goodwill and intangible assets. While management believes that the amounts included in the consolidated financial statements reflect the Company’s best estimates and assumptions, actual results could differ from these estimates. (b) Fair Value Measurements Financial Instruments Subject to Fair Value Measurements Accounting guidance over fair value measurements requires that a fair value measurement reflect the assumptions market participants would use in pricing an asset or liability based on the best information available. Assumptions include the risks inherent in a particular valuation technique (such as a pricing model) and/or the risks inherent in the inputs to the model. The fair value of a financial instrument is the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (the "exit price"). Instruments that the Company owns ("long positions") are marked to bid prices and instruments that the Company has sold but not yet purchased ("short positions") are marked to offer prices. Fair value measurements are not adjusted for transaction costs. Basis of Fair Value Measurement Fair value measurements accounting guidance also establishes a fair value hierarchy that prioritizes the inputs to the respective valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). An asset or liability’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. The three levels of the fair value hierarchy are described further below: ▪ Level 1 - Quoted prices in active markets for identical assets or liabilities (unadjusted); no blockage factors. ▪ Level 2 - Other observable inputs (quoted prices in markets that are not active or inputs that are observable either directly or indirectly)—include quoted prices for similar assets/liabilities (adjusted) other than quoted prices in Level 1; quoted prices in markets that are not active; or other inputs that are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. ▪ Level 3 - Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Unobservable inputs reflect the reporting entity’s own assumptions about the assumptions that market participants would use in pricing the asset or liability. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Details on assets and liabilities that have been included under the requirements of authoritative guidance on fair value measurements to illustrate the bases for determining the fair values of these items held by the Company are included in each respective section of this note. Fair values of investments and derivatives are based on published market values if available, estimates of fair values of similar issues, or estimates of fair values provided by independent pricing services and brokers. Fair values of financial instruments for which quoted market prices are not available or for which the Company believes current trading conditions represent distressed markets are based on estimates using present value or other valuation techniques. The fair values estimated using such techniques are significantly affected by the assumptions used, including the discount rates and the estimated amounts and timing of future cash flows. In such instances, the derived fair value estimates cannot be substantiated by comparison to independent markets and are not necessarily indicative of the amounts that would be realized in a current market exchange. (c) Total Investments Investments - Available For Sale Investments that are considered available for sale (comprised of fixed maturities, equity securities and short-term investments) are carried at fair value. The fair values for available for sale investments are generally sourced from third parties. The fair values of fixed income securities are based upon quoted market values where available, "evaluated bid" prices provided by third party pricing services ("pricing services") where quoted market values are not available, or by reference to broker or underwriter bid indications where pricing services do not provide coverage for a particular security. To the extent the Company believes current trading conditions represent distressed transactions, the Company may elect to utilize internally generated models. It is common industry practice to utilize pricing services as a source for determining the fair values of investments where the pricing services are able to obtain sufficient market corroborating information to allow them to produce a valuation at a reporting date. In addition, in the majority of cases, although a value may be obtained from a particular pricing service for a security or class of similar securities, these values are corroborated against values provided by other pricing services. The pricing services use market approaches to valuations using primarily Level 2 inputs in the vast majority of valuations, or some form of discounted cash flow analysis, to obtain investment values for a small percentage of fixed income securities for which they provide a price. Standard inputs to the valuations provided by the pricing services listed in approximate order of priority for use when available include: reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data. The pricing services may prioritize inputs differently on any given day for any security, and not all inputs listed are available for use in the evaluation process on any given day for each security evaluation; however, the pricing services also monitor market indicators, customer feedback through a price challenge process and industry and economic events. Information of this nature is a trigger to acquire further corroborating market data. When these inputs are not available, they identify "buckets" of similar securities (allocated by asset class types, sectors, sub-sectors, contractual cash flows/structure, and credit rating characteristics) and apply some form of matrix or other modeled pricing to determine an appropriate security value which represents their best estimate as to what a buyer in the marketplace would pay for a security in a current sale. Prices provided by independent pricing services and independent broker quotes can vary widely even for the same security. The use of different methodologies and assumptions may have a material effect on the estimated fair value amounts. While the Company receives values for the majority of the investment securities it holds from pricing services, it is ultimately management’s responsibility to determine whether the values received and recorded in the financial statements are representative of appropriate fair value measurements. Broker/dealer quotations are used to value fixed maturities where prices are unavailable from pricing services due to factors specific to the security such as limited liquidity, lack of current transactions, or trades only taking place in privately negotiated transactions. These are considered Level 3 valuations, as significant inputs utilized by brokers may be difficult to corroborate with observable market data, or sufficient information regarding the specific inputs utilized by the broker was not available to support a Level 2 classification. Equity securities include investments in open end mutual funds and shares of publicly traded hedge funds. The fair value of equity securities is based upon quoted market values (Level 1), or monthly net asset value statements provided by the investment managers upon which subscriptions and redemptions can be executed (Level 2). Short-term investments include investments due to mature within one year from the date of purchase and are valued using the same external factors and in the same manner as fixed income securities. Changes in the value of investments available for sale are reflected as unrealized gains or losses on investments, and are included in "accumulated other comprehensive income (loss)", on a net of tax basis. All investment transactions are recorded on a trade date basis. Realized gains and losses on sales of equities and fixed income investments are determined on a first-in, first-out basis. Investment income is recognized when earned and includes interest and dividend income together with the amortization of premium and discount on fixed maturities and short-term investments, and is recorded net of related investment expenses. Amortization of discounts on fixed maturities includes amortization to expected recovery values for investments that have previously been recorded as other than temporarily impaired. For mortgage-backed securities, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Prepayment fees or call premiums that are only payable to the Company when a security is called prior to its maturity are earned when received and reflected in net investment income. Investments - Trading Investments for which the company has elected the fair value option are classified as trading. Trading securities are carried at fair value with changes included in "Net realized gains (losses) on investments sold." Interest and dividend income from trading securities are included as a component of "Net investment income - Life Funds Withheld Assets" as all trading securities are held in support of the GreyCastle Life Retro Arrangements as defined in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ." Investments Related to Life Retrocession Arrangements written on a Funds Withheld Basis Designated investments that support the GreyCastle Life Retro Arrangements written on a funds withheld basis ("Life Funds Withheld Assets") entered into in connection with the sale of our life reinsurance subsidiary are classified as either available for sale or trading. Investment results for these assets - including interest income, unrealized gains and losses, and gains and losses from sales - are passed directly to the reinsurer pursuant to a contractual arrangement that is accounted for as a derivative. Changes in the fair value of the embedded derivative associated with the GreyCastle Life Retro Arrangements are recorded in "Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets" on the consolidated statements of income. The fair value of the embedded derivative is included within "Funds withheld on life retrocession arrangements, net of future policy benefit reserves recoverable" on the consolidated balance sheets. Investments In Affiliates Investments in which the Company has significant influence over the operating and financial policies of the investee are classified as investments in affiliates on the Company’s balance sheets and are accounted for under the equity method of accounting. Under this method, the Company records its proportionate share of income or loss from such investments in its results for the period as well as its portion of movements in certain of the investee shareholders’ equity balances. When financial statements of the affiliate are not available on a timely basis to record the Company’s share of income or loss for the same reporting periods as the Company, the most recently available financial statements are used. This lag in reporting is applied consistently. Distributions received from affiliates representing returns on invested capital are recorded as operating cash flows, while distributions representing returns of invested capital or proceeds upon sale of all or a portion of an affiliate are recorded as investing cash flows. The Company generally records its hedge fund and private investment fund affiliates on a one -month and three -month lag, respectively, and its operating affiliates on a three -month lag. Significant influence is generally deemed to exist where the Company has an investment of 20% or more in the common stock of a corporation or an investment of 3% or more in closed-end funds, limited partnerships, limited liability companies ("LLCs") or similar investment vehicles. Significant influence is considered for other strategic investments on a case-by-case basis. Investments in affiliates are not subject to fair value measurement guidance as they are not considered to be fair value measured investments under GAAP. However, impairments associated with investments in affiliates that are deemed to be other-than-temporary are calculated in accordance with fair value measurement guidance and appropriate disclosures included within the financial statements during the period the losses are recorded. Other Investments Contained within this asset class are equity interests in investment funds, limited partnerships and unrated tranches of collateralized debt obligations for which the Company does not have sufficient rights or ownership interests to follow the equity method of accounting. The Company accounts for equity securities that do not have readily determinable market values at estimated fair value as it has no significant influence over these entities. Also included within other investments are structured transactions, which are carried at amortized cost. Fair values for other investments, principally other direct equity investments, investment funds and limited partnerships, are primarily based on the net asset value provided by the investment manager, the general partner or the respective entity, recent financial information, available market data and, in certain cases, management judgment, if required. These entities generally carry their trading positions and investments, the majority of which have underlying securities valued using Level 1 or Level 2 inputs, at fair value as determined by their respective investment managers; accordingly, these investments are generally classified as Level 2. Private equity investments are classified as Level 3. The net unrealized gain or loss on investments, net of tax, is included in "Accumulated other comprehensive income (loss)." Any unrealized loss in value considered by management to be other-than-temporary is charged to income in the period in which it is determined. Overseas deposits include investments in private funds related to Lloyd’s syndicates in which the underlying instruments are primarily fixed maturities. The funds themselves do not trade on an exchange and therefore are not included within available for sale securities. Also included in overseas deposits are restricted balances held by Lloyd’s syndicates for solvency purposes which are primarily invested in cash and cash equivalents. Given the restricted nature of these balances, they are included in other investments on the balance sheets. Each of these investment types is considered a Level 2 valuation. The Company has historically participated in structured transactions. These have included providing cash loans supporting project finance transactions, and providing liquidity facility financing to structured project deals. The Company also invested in a payment obligation with an insurance company. The Company's policy is to value such transactions at amortized cost. For further details see Note 4, "Fair Value Measurements " and Note 8, "Other Investments ." (d) Premiums and Acquisition Costs Insurance premiums written are recorded in accordance with the terms of the underlying policies. Reinsurance premiums written are recorded at the inception of the policy and are estimated based upon information received from ceding companies and any subsequent differences arising on such estimates are recorded in the period they are determined. For multi-year reinsurance treaties which are payable in annual installments, generally, only the initial annual installment is included as premiums written at policy inception due to the ability of the reinsured to commute or cancel coverage during the term of the policy. The remaining annual installments are included as premiums written at each successive anniversary date within the multi-year term. Premiums are earned on a pro-rata basis over the period the coverage is provided. Unearned premiums represent the portion of premiums written applicable to the unexpired terms of policies in force. Net premiums earned are presented after deductions for reinsurance ceded, as applicable. Mandatory reinstatement premiums are recognized and earned at the time a loss event occurs. Life and annuity premiums from long duration contracts that transfer significant mortality or morbidity risks are recognized as revenue and earned when due from policyholders. Life and annuity premiums from long duration contracts that do not subject the Company to risks arising from policyholder mortality or morbidity are accounted for as investment contracts and presented within deposit liabilities. The Company has periodically written retroactive loss portfolio transfer contracts. These contracts are evaluated to determine whether they meet the established criteria for reinsurance accounting, and, if so, at inception, written premiums are fully earned and corresponding losses and loss expense recognized. The contracts can cause significant variances in gross premiums written, net premiums written, net premiums earned, and net incurred losses in the years in which they are written. Reinsurance contracts sold not meeting the established criteria for reinsurance accounting are recorded using the deposit method. Acquisition costs, which vary with and are directly related to the acquisition of policies, consist primarily of commissions paid to brokers and cedants, and are deferred and amortized over the period during which the premiums are earned. Acquisition costs are shown net of contractual commissions earned on reinsurance ceded. Future earned premiums, the anticipated losses and other costs (and in the case of a premium deficiency, investment income) related to those premiums, are also considered in determining the level of acquisition costs to be deferred. (e) Reinsurance In the normal course of business, the Company seeks to reduce the potential amount of loss arising from claims events by reinsuring certain levels of risk assumed in various areas of exposure with other insurers or reinsurers. Reinsurance premiums ceded are expensed (and any commissions recorded thereon are earned) on a monthly pro-rata basis over the period the reinsurance coverage is provided. Ceded unearned reinsurance premiums represent the portion of premiums ceded applicable to the unexpired term of policies in force. Mandatory reinstatement premiums ceded are recorded at the time a loss event occurs. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured policy. Provisions are made for estimated unrecoverable reinsurance. The Company enters into reinsurance agreements with other companies in the normal course of business. All premium and loss-related balances related to reinsurance agreements are reported on a gross basis within our consolidated balance sheets, with the exception of the GreyCastle Life Retro Arrangements written on a funds withheld basis. The future policy benefit reserves recoverable related to these retrocession arrangements are netted against the funds withheld liability owing to the counterparty on the consolidated balance sheets due to the contractual right of offset. During the year ended December 31, 2014, the Company recorded $20 million , net of tax, to premiums earned and associated tax accruals, related to reinstatement premiums due under assumed reinsurance contracts arising from unpaid losses and loss expenses reported in a prior period. We evaluated the quantitative and qualitative aspects of this correction and concluded that the impact of recognizing it during the third quarter of 2014 was not material to the consolidated financial statements, nor is it material to previously issued consolidated financial statements in prior periods. (f) Fee Income and Other Fee income and other includes fees received for insurance and product structuring services provided and is earned over the service period of the contract. Any adjustments to fees earned or the service period are reflected in income in the period when determined. (g) Other-Than-Temporary Impairments ("OTTI") of Available for Sale Securities The Company’s process for identifying declines in the fair value of investments that are other-than-temporary involves consideration of several factors. These primary factors include (i) an analysis of the liquidity, business prospects and financial condition of the issuer including consideration of credit ratings, (ii) the significance of the decline, (iii) an analysis of the collateral structure and other credit support, as applicable, of the securities in question, and (iv) for debt securities, whether the Company intends to sell such securities. In addition, the authoritative guidance requires that OTTI for certain asset backed and mortgage backed securities be recognized if the fair value of the security is less than its discounted cash flow value and there has been a decrease in the present value of the expected cash flows since the last reporting period. Where the Company’s analysis of the above factors results in the Company’s conclusion that declines in fair values are other-than-temporary, the cost of the security is written down to discounted cash flow and a portion of the previously unrealized loss is therefore realized in the period such determination is made. If the Company intends to sell an impaired security, or it is more likely than not that it will be required to sell the security before recovery of its amortized cost basis, the impairment is other-than-temporary and is recognized currently in earnings in an amount equal to the entire difference between fair value and amortized cost. In instances in which the Company determines that a credit loss exists but the Company does not intend to sell the security, and it is not more likely than not that the Company will be required to sell the security before the anticipated recovery of its remaining amortized cost basis, the OTTI is separated into (1) the amount of the total impairment related to the credit loss and (2) the amount of the total impairment related to all other factors (i.e. the noncredit portion). The amount of the total OTTI related to the credit loss is recognized in earnings and the amount of the total OTTI related to all other factors is recognized in accumulated other comprehensive loss. The total OTTI is presented in the income statement with an offset for the amount of the total OTTI that is recognized in accumulated other comprehensive income (loss). Absent the intent or requirement to sell a security, if a credit loss does not exist, any impairment is considered to be temporary. The noncredit portion of any OTTI losses on securities classified as available for sale is recorded as a component of other comprehensive income (loss) with an offsetting adjustment to the carrying value of the security. The fair value adjustment could increase or decrease the carrying value of the security. In periods subsequent to the recognition of an OTTI loss, the other-than-temporarily impaired debt security is accounted for as if it had been purchased on the measurement date of the OTTI at an amount equal to the previous amortized cost basis less the credit-related OTTI recognized in earnings. For debt securities for which credit-related OTTI is recognized in earnings, the difference between the new cost basis and the cash flows expected to be collected is accreted into interest income over the remaining life of the security in a prospective manner based on the estimated amount and timing of future estimated cash flows. With respect to securities where the decline in value is determined to be temporary and the security’s amortized cost is not written down, a subsequent decision may be made to sell that security and realize a loss. Subsequent decisions on security sales are made within the context of overall risk monitoring, changing information, market conditions generally and assessing value relative to other comparable securities. We have outsourced a significant portion of the day-to-day management of the Company’s investment portfolio to third party investment manager service providers. While these investment manager service providers may, at a given point in time, believe that the preferred course of action is to hold securities with unrealized losses that are considered temporary until such losses are recovered, the dynamic nature of the portfolio management may result in a subsequent decision to sell the security and realize the loss, based upon a change in market and other factors described above. The Company believes that subsequent decisions to sell such securities are consistent with the classification of the Company’s portfolio as available for sale. There are risks and uncertainties associated with determining whether declines in the fair value of investments are other-than-temporary. These include subsequent significant changes in general economic conditions as well as specific business conditions affecting particular issuers, subjective assessment of issue-specific factors (seniority of claims, collateral value, etc.), future financial market effects, stability of foreign governments and economies, future rating agency actions and significant disclosure of accounting, fraud or corporate governance issues that may adversely affect certain investments. In addition, significant assumptions and management judgment are involved in determining if the decline is other-than-temporary. If management determines that a decline in fair value is temporary, then a security’s value is not written down at that time. However, there are potential effects upon the Company’s future earnings and financial position should management later conclude that some of the current declines in the fair value of the investments are other-than-temporary declines. For further details on the factors considered in evaluation of OTTI see Note 6, "Investments ." (h) Derivative Instruments The Company recognizes all derivatives as either assets or liabilities in the balance sheets and measures those instruments at fair value. Except for the embedded derivative associated with the GreyCastle Life Retro Arrangements discussed above within (c) "Investments Related to Life Retrocession Arrangements written on a Funds Withheld Basis," the changes in fair value of derivatives are shown in the consolidated statements of income as "net realized and unrealized gains and losses on derivative instruments," unless the derivatives are designated as hedging instruments. The accounting for derivatives that are designated as hedging instruments is discussed below. Changes in fair value of derivatives may create volatility in the Company’s results of operations from period to period. Amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) are offset against net fair value amounts recognized in the consolidated balance sheets for derivative instruments executed with the same counterparty under the same netting arrangement to the extent that the Company intends to settle the amounts on a net basis. Derivative contracts can be exchange-traded or over-the-counter ("OTC"). Exchange-traded derivatives (futures and options) typically fall within Level 1 of the fair value hierarchy depending on whether they are deemed to be actively traded or not. OTC derivatives are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market clearing transactions, broker or dealer quotations or alternative pricing sources where an understanding of the inputs utilized in arriving at the valuations is obtained. Where models are used, the selection of a particular model to value an OTC derivative depends upon the contractual terms and specific risks inherent in the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices, yield curves, credit curves, measures of volatility, prepayment rates and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as generic forwards, interest rate swaps and options, model inputs can generally be verified and model selection does not involve significant management judgment. Such instruments comprise the majority of derivatives held by the Company and are typically classified within Level 2 of the fair value hierarchy. Certain OTC derivatives trade in less liquid markets with limited pricing information, or required model inputs that are not directly market corroborated, which causes the determination of fair value for these derivatives to be inherently more subjective. Accordingly, such derivatives are classified within Level 3 of the fair value hierarchy. The valuations of less standard or liquid OTC derivatives are typically based on Level 1 and/or Level 2 inputs that can be observed in the market, as well as unobservable Level 3 inputs. Level 1 and Level 2 inputs are regularly updated to reflect observable market changes. Level 3 inputs are only changed when corroborated by evidence such as similar market transactions, pricing services and/or broker or dealer quotations. The Company conducts its non-hedging derivatives activities in three main areas: investment related derivatives, credit derivatives and other non-investment related derivatives. The Company uses derivative instruments, primarily interest rate swaps, to manage the interest rate exposure associated with certain assets and liabilities. These derivatives are recorded at fair value. On the date the derivative contract is entered into, the Company may designate the derivative as: a hedge of the fair value of a recognized asset or liability ("fair value" hedge); a hedge of the variability in cash flows of a forecasted transaction or of amounts to be received or paid related to a recognized asset or liability ("cash flow" hedge); or a hedge of a net investment in a foreign operation; or the Company may not designate any hedging relationship for a derivative contract. Fair Value Hedges Changes in the fair value of a derivative that is designated and qualifies as a fair value hedge, along with the changes in the fair value of the hedged asset or liability that is attributable to the hedged risk, are recorded in current

Acquisitions and Disposals

Acquisitions and Disposals	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisitions and Disposals	Acquisitions and Disposals (a) Allied Acquisition On February 1, 2016, the Company announced that its indirect, wholly-owned subsidiary, XL Reinsurance America Inc. ("XLRA"), completed the acquisition ("Allied Acquisition") of Allied International Holdings, Inc. ("Allied"), pursuant to the agreement reached with XLRA's parent company, XL America, Inc. ("XLA") on August 11, 2015. Allied is the holding company of Allied Specialty Insurance, Inc. and T.H.E. Insurance Company, a leading insurer of the outdoor entertainment industry in the U.S. The Company made an initial payment of $75.6 million to acquire Allied. Additional contingent consideration will be paid based on production and underwriting profitability over a three year period subsequent to the acquisition date. The target payments of contingent consideration range from $7.5 million to $30.0 million . The Company currently believes the fair market value of these payments to be $15.0 million , for a total initial estimated consideration of $90.6 million . Due to the limited time since the acquisition date, the accounting for the Allied Acquisition is not yet complete; therefore, the calculation of goodwill is still pending at the time of this filing. (b) New Energy Risk On July 24, 2015, the Company purchased, at arm's length, an additional 63.63% interest in New Energy Risk Inc. ("New Energy"), a provider of insurance risk management solutions within the alternative energy sector. A substantial portion of the additional shares were purchased directly from the family trusts of a Company employee who is responsible for managing the business generated by New Energy. Prior to the additional purchase, the Company held a 31.16% ownership interest in New Energy, which was accounted for as an equity method investment. The subsequent purchase raised the Company's ownership stake to 94.79% , which is deemed a controlling financial interest, and hence, the Company now consolidates New Energy. Subsequent to the additional purchase, the family trusts of the employee contributed their remaining 5.21% ownership interest in New Energy to XL Innovate Fund, LP ("XL Innovate Fund"), the entity that holds the Company's interest in New Energy, in partial satisfaction of the employee's aggregate 5.21% investment commitment to XL Innovate Fund. See Note 25, "Related Party Transactions ," for further details of these transactions. The Company paid approximately $8.8 million to acquire the additional interest in New Energy, and realized a gain of approximately $2.5 million , included within income from operating affiliates, in order to the reflect the appropriate fair value adjustment to its existing investment previously accounted for under the equity method. The assets and liabilities of New Energy are now reflected in the consolidated financial statements of the Company based on their fair value as of the acquisition date, while Goodwill of approximately $13.4 million was recorded in conjunction with the transaction. See Note 9, "Goodwill and Other Intangible Assets ," for a further discussion of the goodwill recorded in conjunction with the acquisition. (c) Catlin Acquisition Overview On May 1, 2015 (the "Acquisition Date"), the Company completed its acquisition of the entire issued share capital of Catlin as contemplated by the Implementation Agreement, dated January 9, 2015 (the "Implementation Agreement"), by and among XL-Ireland, Green Holdings Limited, a wholly-owned subsidiary of the Company ("Green Holdings"), and Catlin. Pursuant to the terms of the Implementation Agreement, the Catlin Acquisition was implemented by way of a scheme of arrangement (the "Scheme") under Section 99 of the Companies Act 1981 of Bermuda, as amended (the "Companies Act"), and sanctioned by the Supreme Court of Bermuda (the "Court"). Immediately after such Court action, Catlin was merged with and into Green Holdings under Section 104H of the Companies Act, with Green Holdings as the surviving company, pursuant to the terms of that certain Merger Agreement, dated January 9, 2015 (the "Merger Agreement"), among XL-Ireland, Green Holdings and Catlin. Pursuant to the terms of the Implementation Agreement, XL-Ireland acquired each ordinary share of Catlin, par value $0.01 per share ("Catlin Shares"), for consideration per Catlin Share (the "Acquisition Consideration") equal to 388 pence in cash and 0.130 of an XL-Ireland ordinary share, par value $0.01 per share ("XL Shares"), subject to the mix and match facility set forth in the Implementation Agreement. The XL Shares issued in connection with the Catlin Acquisition are listed on the New York Stock Exchange. The XL Shares issued in connection with the Catlin Acquisition were issued in reliance upon the exemption from registration under the U.S. Securities Act of 1933, as amended (the "Securities Act"), provided by Section 3(a)(10) of the Securities Act. XL-Ireland issued approximately 49.9 million XL Shares and paid approximately £1.49 billion in cash to the holders of Catlin Shares as Acquisition Consideration pursuant to the terms of the Scheme. The foregoing description of the Implementation Agreement and the Merger Agreement is qualified in its entirety by reference to the full text of the Implementation Agreement and Merger Agreement. In connection with the Catlin Acquisition, on January 9, 2015, the Company announced that it was relying on £1.6 billion of debt to be provided under a bridge facility entered into by XLIT Ltd., a wholly-owned subsidiary of the Company ("XL-Cayman"), and arranged by Morgan Stanley Senior Funding, Inc. and Goldman Sachs Bank USA (the "Bridge Facility") for the purposes of discharging the cash component of the Acquisition Consideration. The Company subsequently terminated the commitments under the Bridge Facility as of April 8, 2015, due to a sufficient amount in escrow to discharge the cash portion of the Acquisition Consideration. Costs related to maintaining the Bridge Facility are discussed in "Transaction-related Costs" below. In addition, on January 9, 2015, the Company entered into deal contingent deliverable foreign exchange forwards ("FX Forwards") with Morgan Stanley Capital Services LLC and Goldman Sachs International. The purpose of the FX Forwards was to mitigate risk of foreign currency exposure related to the Catlin Acquisition. Following the closing of the Catlin Acquisition, the FX Forwards were settled. Acquisition Consideration The calculation of the consideration transferred to acquire Catlin Shares is as follows: (In thousands, except per share data) Catlin Shares outstanding as of April 30, 2015 that received share consideration (including the dilutive effect of warrants) 384,118 Exchange ratio per the Implementation Agreement 0.130 XL Share issuance to Catlin shareholders 49,935 Closing price per XL share on April 30, 2015 (1) $ 37.08 XL Share issuance consideration $ 1,851,601 Catlin Shares outstanding as of April 30, 2015 that received cash consideration (including the dilutive effect of warrants) 384,118 Cash price component, per Catlin Share in GBP £ 3.88 Cash consideration, in GBP £ 1,490,377 Foreign exchange rate: GBP/USD on April 30, 2015 $ 1.5349 Cash consideration $ 2,287,579 Total acquisition consideration $ 4,139,180 ____________ (1) The closing market price of XL Shares on the Acquisition Date represents the fair value of XL shares issued as part of the Acquisition Consideration. The Company financed the $2.29 billion cash portion of the Acquisition Consideration by issuing $1.0 billion of subordinated debt, the proceeds (net of debt issuance costs) of which were $980.6 million , and the remaining $1.31 billion by using cash and cash equivalents on hand. See Note 14, "Notes Payable and Debt and Financing Arrangements ," for further information on the debt issuance. Fair Value of Net Assets Acquired and Liabilities Assumed The purchase price was allocated to the acquired assets and assumed liabilities of Catlin based on estimated fair values on the Acquisition Date. The Company recognized goodwill of $794.0 million which is primarily attributable to the synergies and economies of scale expected to result upon integration of Catlin into the Company's operations, including further diversification in geographic mix and product offerings and an increase in distribution strength. As of December 31, 2015, the allocation of the purchase price reflects an increase of $15.9 million in the amount recorded for current and deferred tax liabilities from the allocation initially reported at June 30, 2015 and a corresponding increase in the amount recorded for goodwill. See "Income Taxes" section below for further discussion of the change in the acquired current and deferred tax liabilities. The Company has allocated $466.1 million of this goodwill to its Insurance segment and $327.9 million to its Reinsurance segment. The Company also recognized indefinite lived intangible assets of $673.0 million and other intangible assets of $315.0 million , which will be amortized over their estimated useful lives. See Note 9, "Goodwill and Other Intangible Assets ," for further information. The foregoing allocation of the purchase price is based on information that was available to management at the time the consolidated financial statements were prepared. The allocation may change as additional information becomes available within the measurement period, which cannot exceed 12 months from the Acquisition Date. The fair value recorded for these items may be subject to adjustments, which may impact the individual amounts recorded for assets acquired and liabilities assumed, as well as the residual goodwill. The following table summarizes the fair values of the assets acquired and liabilities assumed at the Acquisition Date: (U.S. dollars in thousands) ASSETS Fixed maturities, at fair value $ 6,266,489 Short-term investments, at fair value 634,599 Equity investments, at fair value 236,230 Investment in affiliates 216,843 Other investments 386,828 Total investments $ 7,740,989 Cash and cash equivalents (1) 1,267,565 Accrued investment income 35,063 Premiums receivable 2,545,188 Unpaid losses and loss expenses recoverable 1,493,267 Reinsurance balances receivable 299,579 Ceded unearned premiums 1,143,852 Deferred acquisition costs and value of business acquired 679,259 Intangible assets 988,000 Receivable from investments sold 9,633 Other assets (2) 306,686 Total assets $ 16,509,081 LIABILITIES Unpaid losses and loss expenses $ 6,933,144 Unearned premiums 3,742,234 Reinsurance balances payable 1,441,749 Notes payable and debt 82,066 Payable for investments purchased 34,149 Deferred tax liability (2) 82,783 Other liabilities (2) 285,481 Total liabilities $ 12,601,606 Net assets acquired before non-controlling interest $ 3,907,475 Non-controlling interest in equity of consolidated subsidiaries 562,285 Net assets acquired $ 3,345,190 Acquisition consideration $ 4,139,180 Goodwill (2) $ 793,990 ____________ (1) Includes Restricted cash. (2) Includes an increase of $15.9 million to goodwill from the amount initially recorded at June 30, 2015, as a result of several tax-related adjustments, including a decrease in other assets of $7.5 million , a decrease in deferred tax liability of $11.3 million , and an increase in other liabilities of $19.8 million . See discussion of "Income Taxes" below for further information. An explanation of the significant adjustments to the components of fair value are as follows: • Deferred acquisition costs and value of business acquired - The adjustment consists of two components. The first adjustment is the elimination of Catlin's deferred acquisition costs asset. The second adjustment is the establishment of the value of business acquired asset, which represents the present value of the expected underwriting profit within the unearned premiums liability, net of reinsurance, less costs to service the related policies and a risk premium. This adjustment will be amortized to underwriting, acquisition and insurance expenses over approximately two years , as the contracts for business in-force as of the Acquisition Date expire. The Company has included $471.0 million in acquisition expenses related to the amortization of the value of business acquired during the year ended December 31, 2015 . • Intangible assets - Establish the estimated fair value of intangible assets related to Catlin. See Note 9, "Goodwill and Other Intangible Assets ," for further information. • Other assets - Establish the estimated fair value of Catlin's internally developed software. • Unpaid losses and loss adjustment expenses - Unpaid losses and loss adjustment expenses acquired include an increase to adjust the carrying value of Catlin's historical unpaid losses and loss adjustment expenses, net of related reinsurance recoverable, to fair value as of the Acquisition Date. The estimated fair value consists of the present value of the expected net loss and loss adjustment expense payments plus a risk premium. This adjustment will be amortized to losses and loss adjustment expenses over approximately 20 years , based on the estimated payout pattern of net reserves as of the Acquisition Date. • Net deferred tax liabilities - The adjustment to deferred tax liabilities is related to the deferred tax impact of the adjustments to fair value as noted above. This net increase of deferred tax liabilities is explained further in "Income Taxes" below. • Non-controlling interest - The fair value was determined based on the last trade price of preferred shares issued by Catlin Insurance Company Limited ("Catlin-Bermuda"). See Note 18, "Share Capital ," for further information. Income Taxes As noted above, during the measurement period, the Company has recorded several tax-related adjustments. These adjustments result from analysis following the filing of Catlin's 2014 tax returns, and a refinement of the jurisdictional fair value allocations of certain assets and liabilities. Other assets decreased by $7.5 million , deferred tax liabilities decreased by $11.3 million , and other liabilities increased by $19.8 million as a result of these adjustments. The net impact was that Goodwill associated with the transaction increased by $15.9 million . Following these measurement period adjustments, the net deferred tax liability recorded by the Company as part of the allocation of the purchase price was $82.8 million . This is primarily comprised of $145.2 million of deferred tax liabilities related to intangible assets, partially offset by deferred tax assets of $62.4 million , which is net of a $90.0 million valuation allowance. Included in the total deferred tax assets are loss carryforwards of $85.8 million with a related $66.8 million valuation allowance. In order to align all U.S. regulated entities under XLA, XLA purchased 100% of the stock of Catlin Inc. from Catlin North America Holdings, Ltd, a U.K. holding company, on September 28, 2015. The transaction, which was contingent upon regulatory approval, resulted in a release of the $59.6 million valuation allowance previously held against the Catlin Inc. deferred tax asset as a benefit through the results of operations. Transaction-related Costs The Company incurred certain acquisition and financing costs associated with the Catlin Acquisition. The Company has recorded $64.7 million of these costs for the year ended December 31, 2015 , of which $50.2 million has been included in Operating Expense and $14.5 million has been included in Interest Expense. Transaction costs included in Operating Expense primarily consist of due diligence, legal, advisory and investment banking costs. Transaction costs included in Interest Expense relate to the maintenance of the Bridge Facility. Pursuant to the terms of the Implementation Agreement, Catlin was required to pay its own costs and expenses in relation to the negotiation, preparation, execution and implementation of the Catlin Acquisition. Costs incurred by Catlin were recorded and paid by Catlin prior to the Acquisition Date and are not included within the Company's consolidated statements of income and comprehensive income. As a part of the ongoing integration of Catlin's operations, the Company incurs costs associated with restructuring the systems, processes and workforce. These costs include such items as severance, retention, facilities and consulting and other costs. The Company separately identifies such costs and includes these expenses within Corporate and Other: (U.S. dollars in thousands) Severance related costs Retention and other compensation costs Facilities-related costs Consulting and other Total Costs incurred in 2015 $ 47,185 $ 35,310 $ 14,744 $ 59,129 $ 156,368 2015 payments 31,058 18,341 13,926 35,754 99,079 Liabilities at December 31, 2015 $ 16,127 $ 16,969 $ 818 $ 23,375 $ 57,289 Financial Results The following table summarizes the financial results of the acquired Catlin subsidiaries since the Acquisition Date that have been included within the Company's consolidated statements of income and comprehensive income as required by ASC 805-10-50-2(h) based on legal entity reporting. These results are not used as a part of management analysis of the financial results and performance of the Company's business. These results are adjusted, where possible, for transaction and integration related costs. These results involve a significant amount of estimates and are not indicative of future results of the acquired Catlin subsidiaries, which will be further impacted by potential changes in targeted business mix, investment management strategies, and synergies recognized from changes in the combined entity's operating structure, as well as the impact of changes in other business and capital management strategies. Since the Acquisition Date, a growing number of underlying policies have been underwritten onto different legal entities, staffing has been allocated to new divisions and activities, and reinsurance has been purchased to cover combined risks, only some of which would have been reflected in the underlying legacy Catlin infrastructure, systems and general ledgers of the acquired Catlin subsidiaries. In future quarters, the summary results of such subsidiaries will be increasingly impractical to produce and even less indicative of the results of the acquired Catlin operations given the significant estimates involved and the nature and pace of our integration activities which are intended to promote the operation of the consolidated group as a whole as quickly as possible. (U.S. dollars in thousands) May 1, 2015 to December 31, 2015 Total revenues - see comments above $ 2,791,789 Net income (loss) - see comments above $ 103,637 Supplemental Pro Forma Information The results of the acquired Catlin operations have been included in the Company's consolidated financial statements from the Acquisition Date to December 31, 2015 . The following table presents unaudited pro forma consolidated information for the years ended December 31, 2015 and 2014 and assumes the Catlin Acquisition occurred on January 1, 2014. The pro forma financial information is presented for informational purposes only and does not necessarily reflect the results that would have occurred had the acquisition taken place on January 1, 2014, nor is it necessarily indicative of future results. Significant adjustments used to determine pro forma results include amortization of intangible assets and amortization of fair value adjustments discussed above, and the corresponding income tax effects. Non-recurring transaction related costs noted above have been included in the unaudited pro forma results for the year ended December 31, 2014 . Unaudited Pro Forma (In thousands, except per share data) 2015 2014 Total revenues $ 10,628,915 $ 10,938,216 Net income attributable to ordinary shareholders 1,221,497 475,914 Earnings (loss) per ordinary share and ordinary share equivalent – basic 4.03 1.50 Earnings (loss) per ordinary share and ordinary share equivalent – diluted 3.97 1.48 (d) Sale of Operating Affiliate On April 1, 2015, XL Re Ltd ("XL Re"), an indirect wholly-owned subsidiary of the Company, completed the sale of all of its shares in ARX Holding Corp. ("ARX") to The Progressive Corporation ("Progressive") pursuant to the terms of the Stock Purchase Agreement with Progressive. XL Re's shares in ARX represented approximately 40.6% of ARX's outstanding capital stock on a fully diluted basis at the time of the announcement. The carrying value of XL Re's shares in ARX was $220.2 million at the time of the sale. XL Re received $560.6 million in proceeds from the transaction, which was based upon the consolidated tangible net book value of ARX and its subsidiaries as of December 31, 2014 , and certain other factors. Thus, the Company recorded a gain of $340.4 million as a result of this transaction that is reflected in the consolidated statement of income for the year ended December 31, 2015 . (e) Sale of Life Reinsurance Subsidiary On May 1, 2014, a wholly owned subsidiary of the Company, XL Insurance (Bermuda) Ltd ("XLIB"), entered into a sale and purchase agreement with GreyCastle Holdings Ltd. ("GreyCastle") providing for the sale of 100% of the common shares of XLIB's wholly-owned subsidiary, XL Life Reinsurance (SAC) Ltd ("XLLR") (subsequent to the transaction, XLLR changed its name to GreyCastle Life Reinsurance (SAC) Ltd ("GCLR")), to GreyCastle for $570 million in cash. This transaction closed on May 30, 2014. As a result of the transaction, the Company ceded the majority of its life reinsurance business to GCLR via 100% quota share reinsurance (the "GreyCastle Life Retro Arrangements"). This transaction covers a substantial portion of our life reinsurance reserves. The Company ceased writing new life reinsurance contracts in 2009 and since that time has been managing the run-off of its life reinsurance operations ("Run-Off Life Operations"). The Run-Off Life Operations business, including the business subject to the transaction, was previously reported within the Company’s Life operations segment. Subsequent to the transaction, the Company no longer considers the Life operations to be a separate operating segment, and the results of the Run-Off Life Operations are reported within "Corporate and Other." See Note 5, "Segment Information " for further information. In addition, certain securities within fixed maturities were reclassified from held to maturity to available for sale in conjunction with this transaction. See Note 6, "Investments ," for further information. All of the reclassified securities are included within Life Funds Withheld Assets, along with certain other available for sale securities as defined in the sale and purchase agreement. The Life Funds Withheld Assets are managed pursuant to agreed investment guidelines that meet the contractual commitments of the XL ceding companies and applicable laws and regulations. All of the investment results associated with the Life Funds Withheld Assets ultimately accrue to GCLR. Because the Company no longer shares in the risks and rewards of the underlying performance of the supporting invested assets, disclosures within the financial statement notes included herein separate the Life Funds Withheld Assets from the rest of the Company's investments. Under the terms of the transaction, the Company continues to own, on a funds withheld basis, assets supporting the GreyCastle Life Retro Arrangements consisting of cash, fixed maturity securities and accrued interest. Based upon the right of offset, the funds withheld liability owing to GCLR is recorded net of future policy benefit reserves recoverable, and is included within "Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable)" on the consolidated balance sheets. The transaction resulted in an overall after-tax U.S. GAAP net loss of $621.3 million . See Note 13, "Future Policy Benefit Reserves ," for a discussion of our future policy benefit reserves, the related future policy benefit reserves recoverable and information about the net funds withheld liability. The impact of the GreyCastle Life Retro Arrangements on the Company's results for the year ended December 31, 2015 and the period beginning from the completion of the transaction on May 30, 2014 through December 31, 2014 was as follows: Impact of GreyCastle Life Retro Arrangements May 30 to December 31, (U.S. dollars in thousands) 2015 2014 Underwriting profit (loss) (1) $ 605 $ 11,649 Net investment income - Life Funds Withheld Assets 187,489 129,575 Net realized gains (losses) on investments sold - Life Funds Withheld Assets 223,272 5,067 Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets (27,734 ) (9 ) OTTI on investments - Life Funds Withheld Assets (13,357 ) (20,587 ) Exchange (gains) losses 4,788 10,099 Other income and expenses 2,280 (1,610 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets (151,691 ) (488,222 ) Net income (loss) $ 225,652 $ (354,038 ) Change in net unrealized gains (losses) on investments - Life Funds Withheld Assets, net of tax (421,604 ) 274,083 Change in adjustments related to future policy benefit reserves, net of tax 170,688 74,009 Change in cumulative translation adjustment - Life Funds Withheld Assets, net of tax 25,869 17,595 Total changes to other comprehensive income as a result of GreyCastle Life Retro Arrangements (2) $ (225,047 ) $ 365,687 Comprehensive income (loss) $ 605 $ 11,649 ____________ (1) The underwriting profit of $0.6 million relates to a premium adjustment relating to the GreyCastle Life Retro Arrangements transaction, which was completed on May 30, 2014. Excluding this transaction, the impact to comprehensive income relating to the GreyCastle Life Retro Arrangements was nil for the years ended December 31, 2015 and 2014 . As shown in the table above, although the Company's net income (loss) is subject to variability related to the GreyCastle Life Retro Arrangements, there is no recurring net impact on the Company's future comprehensive income in any period. The life retrocession embedded derivative value includes the interest income, unrealized gains and losses, and realized gains and losses from sales on the Life Funds Withheld Assets subsequent to May 30, 2014.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair value disclosures	Fair Value Measurements (a) Fair Value Summary The following tables set forth the Company’s assets and liabilities that were accounted for at fair value at December 31, 2015 and 2014 by level within the fair value hierarchy. For further information, see Note 2(b), "Significant Accounting Policies - Fair Value Measurements ": December 31, 2015 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2015 Assets Fixed maturities - Available for Sale ("AFS") - Excluding Life Funds Withheld Assets U.S. Government and Government - Related/Supported $ — $ 5,020,574 $ 45,063 $ — $ 5,065,637 Corporate - Financials — 3,508,224 53,685 — 3,561,909 Corporate - Non Financials — 6,900,259 188 — 6,900,447 Residential mortgage-backed securities – Agency ("RMBS - Agency") — 3,754,894 3,077 — 3,757,971 Residential mortgage-backed securities – Non-Agency ("RMBS - Non-Agency") — 328,540 — — 328,540 Commercial mortgage-backed securities ("CMBS") — 405,316 — — 405,316 Collateralized debt obligations ("CDO") — 2 32,408 — 32,410 Other asset-backed securities — 1,150,715 17,857 — 1,168,572 U.S. States and political subdivisions of the States — 2,632,070 — — 2,632,070 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 5,251,614 — — 5,251,614 Total fixed maturities - AFS - Excluding Life Funds Withheld Assets, at fair value $ — $ 28,952,208 $ 152,278 $ — $ 29,104,486 Equity securities, at fair value 528,581 350,338 — — 878,919 Short-term investments, at fair value (1) — 617,390 — — 617,390 Total investments AFS - Excluding Life Funds Withheld Assets $ 528,581 $ 29,919,936 $ 152,278 $ — $ 30,600,795 Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government - Related/Supported — 12,742 — — 12,742 Corporate - Financials — 598,236 — — 598,236 Corporate - Non Financials — 1,308,628 — — 1,308,628 RMBS - Agency — 752 — — 752 RMBS - Non-Agency — 26,953 — — 26,953 CMBS — 122,481 — — 122,481 Other asset-backed securities — 149,795 — — 149,795 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 933,516 — — 933,516 Total fixed maturities - AFS - Life Funds Withheld Assets, at fair value — 3,153,103 — — 3,153,103 Total investments - AFS, at fair value 528,581 33,073,039 152,278 — 33,753,898 December 31, 2015 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2015 Fixed maturities - Trading U.S. Government and Government - Related/Supported — 4,990 — — 4,990 Corporate - Financials — 335,956 — — 335,956 Corporate - Non Financials — 493,621 — — 493,621 RMBS - Agency — 368 — — 368 CMBS — 4,803 — — 4,803 Other asset-backed securities — 25,700 — — 25,700 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 370,261 — — 370,261 Total fixed maturities - Trading, at fair value — 1,235,699 — — 1,235,699 Short-term investments, at fair value — 60,330 — — 60,330 Total investments Trading — 1,296,029 — — 1,296,029 Cash equivalents (2) 437,742 830,924 — — 1,268,666 Cash equivalents - Life Funds Withheld Assets 517 100,757 — — 101,274 Other investments (3) — 1,008,176 283,550 — 1,291,726 Other assets (4) — 69,914 19,400 (3,087 ) 86,227 Total assets accounted for at fair value $ 966,840 $ 36,378,839 $ 455,228 $ (3,087 ) $ 37,797,820 Liabilities Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) (5) $ — $ 463,915 $ — $ — $ 463,915 Financial instruments sold, but not yet purchased (6) 347 — — — 347 Other liabilities (4) — 16,304 29,191 (3,087 ) 42,408 Total liabilities accounted for at fair value $ 347 $ 480,219 $ 29,191 $ (3,087 ) $ 506,670 December 31, 2014 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2014 Assets Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ — $ 2,171,953 $ — $ — $ 2,171,953 Corporate - Financials — 2,761,916 — — $ 2,761,916 Corporate - Non Financials — 6,010,563 5,894 — $ 6,016,457 Residential mortgage-backed securities – RMBS - Agency — 3,726,666 1,910 — $ 3,728,576 Residential mortgage-backed securities – RMBS - Non-Agency — 427,351 — — $ 427,351 CMBS — 1,052,544 — — $ 1,052,544 CDOs — 4,076 687,958 — $ 692,034 Other asset-backed securities — 1,060,005 5,288 — $ 1,065,293 U.S. States and political subdivisions of the States — 2,021,272 — — $ 2,021,272 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 4,240,073 — — $ 4,240,073 Total fixed maturities - AFS - Excluding Funds Withheld Assets, at fair value $ — $ 23,476,419 $ 701,050 $ — $ 24,177,469 Equity securities, at fair value 502,284 366,008 — — 868,292 Short-term investments, at fair value (1) — 256,727 — — 256,727 Total investments AFS - Excluding Funds Withheld Assets $ 502,284 $ 24,099,154 $ 701,050 $ — $ 25,302,488 December 31, 2014 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2014 Fixed maturities - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ — $ 18,724 $ — $ — $ 18,724 Corporate - Financials — 801,019 — — $ 801,019 Corporate - Non Financials — 2,016,961 — — $ 2,016,961 RMBS – Agency — 3,782 — — $ 3,782 RMBS – Non-Agency — 85,335 — — $ 85,335 CMBS — 193,167 — — $ 193,167 Other asset-backed securities — 273,541 — — $ 273,541 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 1,789,036 — — $ 1,789,036 Total fixed maturities - AFS - Life Funds Withheld Assets, at fair value $ — $ 5,181,565 $ — $ — $ 5,181,565 Total investments - AFS, at fair value $ 502,284 $ 29,280,719 $ 701,050 $ — $ 30,484,053 Fixed maturities - Trading Corporate - Non Financials — 1,171 — — $ 1,171 Total fixed maturities - Trading, at fair value $ — $ 1,171 $ — $ — $ 1,171 Cash equivalents (2) 1,103,877 397,955 — — $ 1,501,832 Cash equivalents - Life Funds Withheld Assets (2) 460 132,738 — — $ 133,198 Other investments (3) — 708,974 185,083 — $ 894,057 Other assets (4) — 122,996 13,663 (696 ) $ 135,963 Total assets accounted for at fair value $ 1,606,621 $ 30,644,553 $ 899,796 $ (696 ) $ 33,150,274 Liabilities Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) (5) $ — $ 450,831 $ — $ — $ 450,831 Financial instruments sold, but not yet purchased (6) 4,737 25,669 — — $ 30,406 Other liabilities (4) — 7,757 23,427 (696 ) $ 30,488 Total liabilities accounted for at fair value $ 4,737 $ 484,257 $ 23,427 $ (696 ) $ 511,725 ____________ (1) Short-term investments consist primarily of Corporate securities and U.S. and Non-U.S. Government and Government-Related/ Supported securities. (2) Cash equivalents balances subject to fair value measurement include certificates of deposit and money market funds. Operating cash balances are not subject to recurring fair value measurement guidance. (3) The Other investments balance excludes certain structured transactions including certain investments in project finance transactions, a payment obligation and liquidity financing provided to a structured credit vehicle as a part of a third party medium term note facility. These investments, which totaled $141.3 million at December 31, 2015 and $354.4 million at December 31, 2014 , are carried at amortized cost. For further information, see Note 8, "Other Investments ." (4) Other assets and other liabilities include derivative instruments. The derivative balances included in each category are reported on a gross basis by level with a netting adjustment presented separately in the Collateral and Counterparty Netting column. The fair values of the individual derivative contracts are reported gross in their respective levels based on the fair value hierarchy. For further details regarding derivative fair values and associated collateral received or paid see Note 15, "Derivative Instruments ." (5) Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) include balances related to the life retrocession embedded derivative, under which all investment results associated with the Life Funds Withheld Assets related the GreyCastle Life Retro Arrangements described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ", accrue to the benefit of GCLR. (6) Financial instruments sold, but not yet purchased, represent "short sales" and are included within "Payable for investments purchased" on the balance sheets. (b) Level 2 Asset Valuations U.S. Government and Government - Related/Supported, Corporate - Financials, Corporate - Non Financials and Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported Transaction activity inputs utilized in the valuation of fair value hierarchy Level 2 securities within these sub-categories include actual trades, dealer posts, results of bids-wanted, institutional secondary offerings, primary market offerings and Trade Reporting and Compliance Engine ("TRACE") trade feeds. As part of the evaluation process, transaction activity is compared to prior evaluations and necessary adjustments are made accordingly. Market-color inputs include actively quoted benchmark issues, buy-side/evaluator dialogue, sell-side/evaluator dialogue and credit derivative indices. RMBS - Agency, RMBS - Non-Agency, CMBS, CDO and Other asset-backed securities As part of the fair valuation process, Level 2 securities in these sub-categories are analyzed by collateral type, deal structure, deal performance and vintage. Market inputs into the valuation process for each sub-category include reported or observed trades, results of bids-wanted, buy-side/sell-side evaluator dialogue, dealer offering and market research reports. Cash flow inputs into the evaluation process include conditional prepayment rates, conditional decay rates, delinquency and loss severity rates. This assumptive data is reviewed and updated using third party reported information to reflect current market convention. U.S. States and political subdivisions of the States Transaction activity inputs utilized in the valuation of fair value hierarchy Level 2 securities within this sub-category include client and broker trades, dealer posts, results of bids-wanted, institutional secondary offerings, primary market offerings, and Municipal Securities Rulemaking trade feeds. As part of the evaluation process, transaction activity is compared to prior evaluations and necessary adjustments are made accordingly. Market-color inputs include bids, offerings, two-sided markets, buy-side/evaluator dialogue and sell-side/evaluator dialogue. Credit information inputs include issuer financial statements, default and material event notices, developer reports and liquidation and restructuring analysis. Equity securities and other investments Other investment securities generally include investments in thinly traded equity funds and hedge funds. Fair value is determined based upon the most recent net asset values (“NAV’) received from the fund administrators, the nature of the underlying investments in the funds and the frequency of subscriptions or redemptions as dictated by the fund’s governing documents. Other assets and other liabilities Other assets and other liabilities primarily include over-the-counter (“OTC”) derivatives, which are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market clearing transactions, broker or dealer quotations or alternative independent pricing sources where an understanding of the inputs utilized in arriving at the valuations is obtained. Where models are used, the selection of a particular model to value an OTC derivative depends upon the contractual terms and specific risks inherent in the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices, yield curves, credit curves, measures of volatility, prepayment rates and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as generic forwards, interest rate swaps and options, model inputs can generally be verified and model selection does not involve significant management judgment. (c) Level 3 Assets and Liabilities The tables below present additional information about assets and liabilities measured at fair value on a recurring basis and for which Level 3 inputs were utilized to determine fair value. The tables present a reconciliation of the beginning and ending balances for the years ended December 31, 2015 and 2014 for all financial assets and liabilities measured at fair value using significant unobservable inputs (Level 3) at December 31, 2015 and 2014 , respectively. The tables do not include gains or losses that were reported in Level 3 in prior periods for assets that were transferred out of Level 3 prior to December 31, 2015 and 2014 , respectively. Gains and losses for assets and liabilities classified within Level 3 in the table below may include changes in fair value that are attributable to both observable inputs (Levels 1 and 2) and unobservable inputs (Level 3). Further, it should be noted that the following tables do not take into consideration the effect of offsetting Level 1 and 2 financial instruments entered into by the Company that are either economically hedged by certain exposures to the Level 3 positions or that hedge the exposures in Level 3 positions. In general, Level 3 assets include securities for which values were obtained from brokers where either significant inputs were utilized in determining the values that were difficult to corroborate with observable market data, or sufficient information regarding the specific inputs utilized by the broker was not available to support a Level 2 classification. Transfers into or out of Level 3 primarily arise as a result of the valuations utilized by the Company changing between either those provided by independent pricing services that do not contain significant unobservable inputs and other valuations sourced from brokers that are considered Level 3. Fixed maturities and short-term investments The Company’s Level 3 assets consist primarily of U.S. Government and Government-Related/Supported, Corporates and CDOs, for which non-binding broker quotes are the primary source of the valuations. Sufficient information regarding the specific inputs utilized by the brokers was not available to support a Level 2 classification. The Company obtains the majority of broker quotes for these securities from third party investment managers who perform independent verifications of these valuations using pricing matrices based upon information gathered by market traders. In addition, for the majority of these securities, the Company compares the broker quotes to independent valuations obtained from third party pricing vendors, which may also consist of broker quotes, to assess if the prices received represent a reasonable estimate of the fair value. Although the Company does not have access to the specific unobservable inputs that may have been used in the fair value measurements of these securities provided by brokers, we would expect that the significant inputs considered are prepayment rates, probability of default, loss severity in the event of default, recovery rates, liquidity premium and reinvestment rates. Significant increases (decreases) in any of those inputs in isolation could result in a significantly different fair value measurement. Generally, a change in the assumption used for the probability of default is accompanied by a directionally similar change in the assumption used for the loss severity and a directionally opposite change in the assumption used for prepayment rates. The remainder of the Level 3 assets relate primarily to private investments (including funds) and certain derivative positions as described below. Other investments Included within the other investments component of the Company’s Level 3 valuations are private investments (including funds) and hedge funds where the Company is not deemed to have significant influence over the investee. The fair value of these investments is based upon net asset values received from the investment manager or general partner of the respective entity. The nature of the underlying investments held by the investee that form the basis of the net asset value include assets such as private business ventures and are such that significant Level 3 inputs are utilized in the determination of the individual underlying holding values and, accordingly, the fair value of the Company’s investment in each entity is classified within Level 3. The Company has not adjusted the net asset values received; however, management incorporates factors such as the most recent financial information received, annual audited financial statements and the values at which capital transactions with the investee take place when applying judgment regarding whether any adjustments should be made to the net asset value in recording the fair value of each position. Investments in hedge funds included in other investments utilize strategies including arbitrage, directional, event driven and multi-style. The funds potentially have lockup and gate provisions which may limit redemption liquidity. For further details regarding the nature of other investments and related features, see Note 8, "Other Investments ," for further details. Derivative instruments Derivative instruments recorded within other liabilities and classified within Level 3 include credit derivatives sold providing protection on senior tranches of structured finance transactions where the value is obtained directly from the investment bank counterparty and sufficient information regarding the inputs utilized in such valuation was not obtained to support a Level 2 classification and guaranteed minimum income benefits embedded within one reinsurance contract. The majority of inputs utilized in the valuations of these types of derivative contracts are considered Level 1 or Level 2; however, each valuation includes at least one Level 3 input that was significant to the valuation and, accordingly, the values are disclosed within Level 3. The calculation of the change in fair value of the embedded derivative associated with the Life Retro Arrangements includes the interest income, realized and unrealized gains and losses on Life Funds Withheld Assets and certain related expenses related to the Life Funds Withheld Assets. The fair value of the embedded derivative is included in “Funds withheld on life retrocession arrangements, net of future policy benefit reserves recoverable” on the consolidated balance sheets. The fair value of the embedded derivative is considered a Level 2 valuation. Level 3 Assets and Liabilities - Year Ended December 31, 2015 (U.S. dollars in thousands) U.S. Government and Government - Related/Supported Corporate - Financials Corporate - Non-Financials RMBS - Agency Balance, beginning of period $ — $ — $ 5,894 $ 1,910 Realized gains (losses) — 9 (186 ) — Movement in unrealized gains (losses) — (10 ) (13 ) (3 ) Purchases and issuances (1) 35,044 53,686 (123 ) 1,297 Sales — — — — Settlements — — (316 ) (323 ) Transfers into Level 3 10,019 — — 3,059 Transfers out of Level 3 — — (5,068 ) (2,863 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ 45,063 $ 53,685 $ 188 $ 3,077 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ (2 ) $ (153 ) $ (2 ) RMBS - Non CMBS CDO Other asset- Balance, beginning of period $ — $ — $ 687,958 $ 5,288 Realized gains (losses) — — (8,658 ) 628 Movement in unrealized gains (losses) — — 16,688 (599 ) Purchases and issuances (1) — — 25,882 46,940 Sales — — (366,633 ) (7,269 ) Settlements — — (322,829 ) (6,359 ) Transfers into Level 3 — — — 13,317 Transfers out of Level 3 — — — (34,089 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 32,408 $ 17,857 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 5,279 $ 451 Non-US Sovereign Short-term Other investments Derivative Contracts Balance, beginning of period $ — $ — $ 185,083 $ (9,764 ) Realized gains (losses) — — 15,270 — Movement in unrealized gains (losses) — — (12,548 ) (27 ) Purchases and issuances (1) — — 117,143 — Sales — — (1,417 ) — Settlements — — (19,981 ) — Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 283,550 $ (9,791 ) Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 2,724 $ 80 ____________ (1) Includes assets acquired as result of the transaction described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition " Level 3 Assets and Liabilities - Year Ended December 31, 2014 (U.S. dollars in thousands) U.S. Government and Government - Related/Supported Corporate - Financials Corporate - Non-Financials RMBS - Agency Balance, beginning of period $ — $ — $ 31,573 $ 10,473 Realized gains (losses) — — 199 5 Movement in unrealized gains (losses) — — (128 ) (18 ) Purchases and issuances — — 3,759 120 Sales — — — — Settlements — — (6,543 ) (3,205 ) Transfers into Level 3 — — 766 — Transfers out of Level 3 — — (23,732 ) (5,465 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 5,894 $ 1,910 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 60 $ (12 ) RMBS - Non Agency CMBS CDO Other asset- backed securities Balance, beginning of period $ 9 $ 12,533 $ 710,253 $ 11,877 Realized gains (losses) 1 3 3,781 (7 ) Movement in unrealized gains (losses) 1 (3 ) 11,604 65 Purchases and issuances — 1,376 185,710 5,182 Sales — — (48,313 ) — Settlements (11 ) (12,533 ) (175,077 ) (5,705 ) Transfers into Level 3 — — — — Transfers out of Level 3 — (1,376 ) — (6,124 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 687,958 $ 5,288 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 14,432 $ 57 Non-US Sovereign Government, Provincial, Supranational and Government Related/Supported Short-term investments Other investments Derivative Contracts - Net Balance, beginning of period $ — $ 2,015 $ 113,472 $ (29,110 ) Realized gains (losses) — — 12,676 — Movement in unrealized gains (losses) — (15 ) 538 19,346 Purchases and issuances — — 59,401 — Sales — — — — Settlements — (2,000 ) (25,498 ) — Transfers into Level 3 — — 24,494 — Transfers out of Level 3 — — — — Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 185,083 $ (9,764 ) Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 13,212 $ 19,346 (d) Financial Instruments Not Carried at Fair Value Authoritative guidance over disclosures about the fair value of financial instruments requires additional disclosure of fair value information for financial instruments not carried at fair value in both interim and annual reporting periods. Certain financial instruments, particularly insurance contracts, are excluded from these fair value disclosure requirements. The carrying values of cash and cash equivalents, accrued investment income, net receivable from investments sold, other assets, net payable for investments purchased, other liabilities and other financial instruments not included below approximated their fair values. The following table includes financial instruments for which the carrying value differs from the estimated fair values at December 31, 2015 and 2014 . All of these fair value estimates are considered Level 2 fair value measurements. (U.S. dollars in thousands) 2015 2014 Carrying Value Fair Value Carrying Value Fair Value Financial Assets - Other investments, structured transactions $ 141,329 $ 154,065 $ 354,382 $ 371,625 Deposit liabilities $ 1,168,376 $ 1,436,210 $ 1,245,367 $ 1,543,761 Notes payable and debt 2,644,970 2,805,152 1,662,580 1,897,854 Financial Liabilities $ 3,813,346 $ 4,241,362 $ 2,907,947 $ 3,441,615 The Company historically participated in structured transactions. Our remaining structured transaction is an investment in a payment obligation with an insurance company. This transaction is carried at amortized cost. The fair value of this investment held by the Company is determined through use of an internal model utilizing benchmark yields, issuer spreads and reference data. Deposit liabilities include obligations under structured insurance and reinsurance transactions. For purposes of fair value disclosures, the Company determined the estimated fair value of the deposit liabilities by assuming a discount rate equal to the appropriate U.S. Treasury rate plus 26.5 basis points and 29.5 basis points at December 31, 2015 and 2014 , respectively. The discount rate incorporates the Company’s own credit risk into the determination of estimated fair value. The fair values of the Company’s notes payable and debt outstanding were determined based on quoted market prices. There are no significant concentrations of credit risk within the Company’s financial instruments as defined in the authoritative guidance over disclosures of fair value of financial instruments not carried at fair value, which excludes certain financial instruments, particularly insurance contracts.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information The Company is organized into two operating segments: Insurance and Reinsurance. Subsequent to the transaction described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," the underwriting results of the acquired businesses from the Acquisition Date through December 31, 2015 are included in the Company's Insurance or Reinsurance segment, as appropriate. The Company’s general investment and financing operations are reflected in "Corporate and Other." Subsequent to the transaction described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ," GCLR reinsures the majority of the Company's life reinsurance business through the GreyCastle Life Retro Arrangements. The results of the Run-Off Life Operations not subject to the Life Retro Arrangements are also reported within Corporate and Other. The Company evaluates the performance of both the Insurance and Reinsurance segments based on underwriting profit. Other items of revenues and expenditures of the Company are not evaluated at the segment level. In addition, the Company does not allocate investment assets used to support its Property and Casualty ("P&C") operations to the individual segments, except as noted below. Investment assets related to the Company’s Run-Off Life Operations and certain structured products included in the Insurance and Reinsurance segments are held in separately identified portfolios. The following tables summarize the segment results for the indicated years ended: Year Ended December 31, 2015 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate and Other (1) Total Gross premiums written $ 8,395,846 $ 2,273,163 $ 10,669,009 $ 309,916 $ 10,978,925 Net premiums written 5,859,934 2,028,890 7,888,824 62,239 7,951,063 Net premiums earned 5,648,482 2,515,702 8,164,184 62,241 8,226,425 Net losses and loss expenses (2) 3,614,048 1,152,152 4,766,200 115,997 4,882,197 Acquisition costs (2) 704,364 602,290 1,306,654 10,794 1,317,448 Operating expenses (3) 1,154,760 283,379 1,438,139 1,232 1,439,371 Underwriting profit (loss) $ 175,310 $ 477,881 $ 653,191 $ (65,782 ) $ 587,409 Net investment income - excluding Life Funds Withheld Assets (4) 583,871 40,569 624,440 Net investment income - Life Funds Withheld Assets 187,489 187,489 Net results from structured products (5) 12,185 5,806 17,991 — 17,991 Net fee income and other (6) (16,936 ) 2,958 (13,978 ) 622 (13,356 ) Extinguishment of debt — 5,592 5,592 Net realized gains (losses) on investments - excluding Life Funds Withheld Assets 14,586 5,411 19,997 Net realized gains (losses) on investments and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets — 182,181 182,181 Net realized and unrealized gains (losses) on derivative instruments — 53,123 53,123 Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets — (151,691 ) (151,691 ) Net income (loss) from investment fund affiliates and operating affiliates — 118,060 118,060 Gain on sale of operating affiliate 340,407 340,407 Exchange (gains) losses — 22,504 22,504 Corporate operating expenses — 480,755 480,755 Contribution from P&C and Corporate and Other 1,255,661 201,538 1,457,199 Interest expense (7) 163,021 163,021 Non-controlling interests 106,187 106,187 Income tax expense (19,161 ) (19,161 ) Net income (loss) attributable to ordinary shareholders $ 1,207,152 Ratios – P&C operations: (8) Loss and loss expense ratio 64.0 % 45.8 % 58.4 % Underwriting expense ratio 32.9 % 35.2 % 33.6 % Combined ratio 96.9 % 81.0 % 92.0 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) The Company has reflected the amortization of certain fair value adjustments recorded in conjunction with the Catlin Acquisition within the respective segments. (3) Operating expenses of the segments exclude Corporate operating expenses, shown separately. (4) Net investment income - excluding Life Funds Withheld Assets does not include net investment income related to the net results from structured products. (5) The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million , respectively. (6) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (7) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (8) Ratios are based on net premiums earned from P&C operations. Year Ended December 31, 2014 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate & Other (1) Total Gross premiums written $ 5,976,011 $ 1,785,479 $ 7,761,490 $ 333,436 $ 8,094,926 Net premiums written 4,134,151 1,633,058 5,767,209 177,632 5,944,841 Net premiums earned 4,026,713 1,690,725 5,717,438 177,632 5,895,070 Net losses and loss expenses 2,543,108 715,285 3,258,393 242,963 3,501,356 Acquisition costs 393,319 330,684 724,003 14,115 738,118 Operating expenses (2) 865,592 193,404 1,058,996 10,693 1,069,689 Underwriting profit (loss) $ 224,694 $ 451,352 $ 676,046 $ (90,139 ) $ 585,907 Net investment income - excluding Life Funds Withheld Assets (3) 574,458 146,558 721,016 Net investment income - Life Funds Withheld Assets 129,575 129,575 Net results from structured products (4) 43,710 10,499 54,209 — 54,209 Net fee income and other (5) (10,051 ) 2,800 (7,251 ) 360 (6,891 ) Loss on sale of life reinsurance subsidiary — 666,423 666,423 Net realized gains (losses) on investments 119,366 3,625 122,991 Net realized gains (losses) on investments - Life Funds Withheld Assets — (15,529 ) (15,529 ) 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 ) Net income (loss) from investment fund affiliates and operating affiliates — 203,034 203,034 Exchange (gains) losses — (37,568 ) (37,568 ) Corporate operating expenses — 220,165 220,165 Contribution from P&C and Corporate and Other 1,416,828 (929,872 ) 486,956 Interest expense (6) 121,221 121,221 Non-controlling interests 80,498 80,498 Income tax expense 96,897 96,897 Net income (loss) attributable to ordinary shareholders $ 188,340 Ratios – P&C operations: (7) Loss and loss expense ratio 63.2 % 42.3 % 57.0 % Underwriting expense ratio 31.2 % 31.0 % 31.2 % Combined ratio 94.4 % 73.3 % 88.2 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) Operating expenses of the segments exclude Corporate operating expenses, shown separately. (3) Net investment income does not include net investment income related to the net results from structured products. (4) The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million , respectively. (5) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (6) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (7) Ratios are based on net premiums earned from P&C operations. Year Ended December 31, 2013 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate and Other (1) Total Gross premiums written $ 5,523,181 $ 1,893,611 $ 7,416,792 $ 324,343 $ 7,741,135 Net premiums written 4,154,093 1,749,889 5,903,982 295,422 6,199,404 Net premiums earned 4,267,677 1,746,422 6,014,099 295,422 6,309,521 Net losses and loss expenses 2,829,999 901,465 3,731,464 465,702 4,197,166 Acquisition costs 529,270 353,388 882,658 26,665 909,323 Operating expenses (2) 782,677 166,238 948,915 8,926 957,841 Underwriting profit (loss) $ 125,731 $ 325,331 $ 451,062 $ (205,871 ) $ 245,191 Net investment income (3) 599,144 286,645 885,789 Net results from structured products (4) 15,562 8,229 23,791 — 23,791 Net fee income and other (5) (9,317 ) 2,320 (6,997 ) 1,305 (5,692 ) Net realized gains (losses) on investments 85,792 1,985 87,777 Net realized and unrealized gains (losses) on derivative instruments — 7,798 7,798 Net income (loss) from investment fund affiliates and operating affiliates — 258,195 258,195 Exchange (gains) losses — (28,243 ) (28,243 ) Corporate operating expenses — 209,454 209,454 Contribution from P&C and Corporate and Other 1,152,792 168,846 1,321,638 Interest expense (6) 107,486 107,486 Non-controlling interests 76,731 76,731 Income tax expense 77,505 77,505 Net income (loss) attributable to ordinary shareholders $ 1,059,916 Ratios – P&C operations: (7) Loss and loss expense ratio 66.3 % 51.6 % 62.0 % Underwriting expense ratio 30.8 % 29.8 % 30.5 % Combined ratio 97.1 % 81.4 % 92.5 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) Operating expenses exclude Corporate operating expenses, shown separately. (3) Net investment income does not include net investment income related to the net results from structured products. (4) The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million , respectively. (5) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (6) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (7) Ratios are based on net premiums earned from P&C operations. The following tables summarize the Company’s net premiums earned by line of business: Year Ended December 31, 2015 (U.S. dollars in thousands) Insurance Reinsurance Corporate and Other Total P&C Operations: Professional $ 1,163,302 $ 168,367 $ — $ 1,331,669 Casualty 1,685,748 468,286 — 2,154,034 Property catastrophe — 663,958 — 663,958 Property 1,021,037 869,286 — 1,890,323 Specialty 1,473,929 127,797 — 1,601,726 Other (1) 304,466 218,008 — 522,474 Total P&C Operations $ 5,648,482 $ 2,515,702 $ — $ 8,164,184 Corporate and Other: Run-off life operations - Annuity — — 1 1 Run-off life operations - Other life — — 62,240 62,240 Total Corporate and Other $ — $ — $ 62,241 $ 62,241 Total $ 5,648,482 $ 2,515,702 $ 62,241 $ 8,226,425 Year Ended December 31, 2014 P&C Operations: Professional $ 1,075,420 $ 181,223 $ — $ 1,256,643 Casualty 1,422,684 300,223 — 1,722,907 Property catastrophe — 433,602 — 433,602 Property 544,856 555,583 — 1,100,439 Specialty 737,281 95,745 — 833,026 Other (1) 246,472 124,349 — 370,821 Total P&C Operations $ 4,026,713 $ 1,690,725 $ — $ 5,717,438 Corporate and Other: Run-off life operations - Annuity $ — $ — $ 53,363 $ 53,363 Run-off life operations - Other life — — 124,269 124,269 Total Corporate and Other $ — $ — $ 177,632 $ 177,632 Total $ 4,026,713 $ 1,690,725 $ 177,632 $ 5,895,070 Year Ended December 31, 2013 P&C Operations: Professional $ 1,370,196 $ 206,169 $ — $ 1,576,365 Casualty 1,389,851 312,156 — 1,702,007 Property catastrophe — 492,568 — 492,568 Property 544,278 561,105 — 1,105,383 Specialty 732,042 94,797 — 826,839 Other (1) 231,310 79,627 — 310,937 Total P&C Operations $ 4,267,677 $ 1,746,422 $ — $ 6,014,099 Corporate and Other: Run-off life operations - Annuity $ — $ — $ 122,715 $ 122,715 Run-off life operations - Other life — — 172,707 172,707 Total Corporate and Other $ — $ — $ 295,422 $ 295,422 Total $ 4,267,677 $ 1,746,422 $ 295,422 $ 6,309,521 ____________ (1) Other within the Insurance segment includes: excess and surplus, programs, surety, structured indemnity and certain discontinued lines. Other within the Reinsurance segment includes: whole account contracts, accident and health and other lines. The following table shows an analysis of the Company’s net premiums written by geographical location of subsidiary where the premium is written for the years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 P&C Operations: Bermuda $ 781,618 $ 636,109 $ 658,041 United States 3,045,031 2,528,196 2,650,916 Europe 3,628,258 2,124,117 2,111,065 Other 433,917 478,787 483,960 Total P&C Operations $ 7,888,824 $ 5,767,209 $ 5,903,982 Corporate and Other: Bermuda $ 62,276 $ 91,979 $ 117,948 Europe (37 ) 85,653 177,474 Total Corporate and Other $ 62,239 $ 177,632 $ 295,422

Investments

Investments	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investments	Investments (a) Fixed Maturities, Short-Term Investments and Equity Securities Classification of Fixed Income Securities During the second quarter of 2014, fixed maturities with a carrying value of $2.8 billion were reclassified from held to maturity ("HTM") to AFS in conjunction with the sale of XLLR as discussed in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ." Gross unrealized gains and gross unrealized losses, net of tax, of $424.9 million and nil , respectively, related to these securities were recognized in other comprehensive income on the date of transfer. For certain annuity contracts that are subject to the GreyCastle Life Retro Arrangements, policy benefit reserves were historically increased for the impact of changes in unrealized gains on investments supporting such contracts as if the gains had been realized, with a corresponding entry to other comprehensive income ("Shadow Adjustments"). In conjunction with the sale of XLLR and the related reclassification of securities from HTM to AFS, the Company recorded an additional gross charge of $440.5 million , net of tax, as a reduction of comprehensive income for such Shadow Adjustments on the date of the transfer. See Note 20, "Accumulated Other Comprehensive Income (Loss) ," for further information. All of the reclassified securities are included within the Life Funds Withheld Assets, along with certain other available for sale securities as defined in the sale and purchase agreement. The Life Funds Withheld Assets are managed pursuant to agreed upon investment guidelines that meet the contractual commitments of the XL ceding companies and applicable laws and regulations. All of the investment results associated with the Life Funds Withheld Assets ultimately accrue to GCLR. Because the Company no longer shares in the risks and rewards of the underlying performance of the Life Funds Withheld Assets, disclosures within the financial statements and accompanying notes included herein separate the Life Funds Withheld Assets from the rest of the Company's investments. Amortized Cost and Fair Value Summary The cost (amortized cost for fixed maturities and short-term investments), fair value, gross unrealized gains and gross unrealized (losses), including non-credit related OTTI recorded in accumulated other comprehensive income ("AOCI") of the Company’s AFS investments at December 31, 2015 and 2014 were as follows: Included in AOCI December 31, 2015 (U.S. dollars in thousands) Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Non-credit Related OTTI (1) Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 5,047,621 $ 52,355 $ (34,339 ) $ 5,065,637 $ — Corporate - Financials 3,535,830 49,535 (23,456 ) 3,561,909 — Corporate - Non Financials 6,867,525 130,568 (97,646 ) 6,900,447 — RMBS – Agency 3,697,756 77,776 (17,561 ) 3,757,971 — RMBS – Non-Agency 319,876 25,644 (16,980 ) 328,540 (54,200 ) CMBS 401,713 7,933 (4,330 ) 405,316 (1,182 ) CDO 41,679 4 (9,273 ) 32,410 (1,208 ) Other asset-backed securities 1,164,426 17,665 (13,519 ) 1,168,572 (1,144 ) U.S. States and political subdivisions of the States 2,514,048 125,395 (7,373 ) 2,632,070 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 5,249,148 100,383 (97,917 ) 5,251,614 — Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 28,839,622 $ 587,258 $ (322,394 ) $ 29,104,486 $ (57,734 ) Total short-term investments - Excluding Life Funds Withheld Assets 618,851 967 (2,428 ) 617,390 — Total equity securities 834,079 89,993 (45,153 ) 878,919 — Total investments - AFS - Excluding Life Funds Withheld Assets $ 30,292,552 $ 678,218 $ (369,975 ) $ 30,600,795 $ (57,734 ) Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 10,721 $ 2,021 $ — $ 12,742 $ — Corporate - Financials 531,016 67,220 — 598,236 — Corporate - Non Financials 1,132,926 175,702 — 1,308,628 — RMBS – Agency 591 161 — 752 — RMBS – Non-Agency 24,401 2,552 — 26,953 — CMBS 107,968 14,513 — 122,481 — Other asset-backed securities 132,674 17,121 — 149,795 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 737,735 195,781 — 933,516 — Total fixed maturities - AFS - Life Funds Withheld Assets $ 2,678,032 $ 475,071 $ — $ 3,153,103 $ — Total investments - AFS $ 32,970,584 $ 1,153,289 $ (369,975 ) $ 33,753,898 $ (57,734 ) ____________ (1) Represents the non-credit component of OTTI losses, adjusted for subsequent sales of securities. It does not include the change in fair value subsequent to the impairment measurement date. December 31, 2014 (U.S. dollars in thousands) Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Non-credit Related OTTI (1) Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 2,100,851 $ 77,889 $ (6,787 ) $ 2,171,953 $ — Corporate - Financials 2,687,797 87,058 (12,939 ) 2,761,916 — Corporate - Non Financials 5,774,333 278,747 (36,623 ) 6,016,457 (3,309 ) RMBS – Agency 3,625,171 114,188 (10,783 ) 3,728,576 — RMBS – Non-Agency 404,398 41,108 (18,155 ) 427,351 (67,918 ) CMBS 1,033,819 23,987 (5,262 ) 1,052,544 (2,033 ) CDOs 717,544 1,659 (27,169 ) 692,034 (1,663 ) Other asset-backed securities 1,028,528 42,810 (6,045 ) 1,065,293 (1,797 ) U.S. States and political subdivisions of the States 1,892,566 129,910 (1,204 ) 2,021,272 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 4,162,425 139,484 (61,836 ) 4,240,073 — Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 23,427,432 $ 936,840 $ (186,803 ) $ 24,177,469 $ (76,720 ) Total short-term investments - Excluding Life Funds Withheld Assets $ 257,221 $ 49 $ (543 ) $ 256,727 $ — Total equity securities - Excluding Life Funds Withheld Assets $ 763,833 $ 130,689 $ (26,230 ) $ 868,292 $ — Total investments - AFS - Excluding Life Funds Withheld Assets $ 24,448,486 $ 1,067,578 $ (213,576 ) $ 25,302,488 $ (76,720 ) Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 14,866 $ 3,858 $ — $ 18,724 $ — Corporate - Financials 701,587 99,432 — 801,019 — Corporate - Non Financials 1,706,262 310,699 — 2,016,961 — RMBS – Agency 3,301 481 — 3,782 — RMBS – Non-Agency 71,075 14,260 — 85,335 — CMBS 168,886 24,281 — 193,167 — Other asset-backed securities 238,168 35,373 — 273,541 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 1,397,194 391,842 — 1,789,036 — Total fixed maturities - AFS - Life Funds Withheld Assets $ 4,301,339 $ 880,226 $ — $ 5,181,565 $ — Total investments - AFS $ 28,749,825 $ 1,947,804 $ (213,576 ) $ 30,484,053 $ (76,720 ) ____________ (1) Represents the non-credit component of OTTI losses, adjusted for subsequent sales of securities. It does not include the change in fair value subsequent to the impairment measurement date. The cost (amortized cost for fixed maturities and short-term investments) and fair value of the Company’s Trading investments at December 31, 2015 and 2014 were as follows: December 31, 2015 (U.S. dollars in thousands) Amortized Fair Value Fixed maturities - Trading - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 4,957 $ 4,990 Corporate - Financials 344,070 335,956 Corporate - Non Financials 509,441 493,621 RMBS – Agency 370 368 CMBS 4,874 4,803 Other asset-backed securities 26,405 25,700 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 373,492 370,261 Total fixed maturities - Trading - Life Funds Withheld Assets $ 1,263,609 $ 1,235,699 Total short-term investments - Trading - Life Funds Withheld Assets $ 60,176 $ 60,330 Total investments - Trading - Life Funds Withheld Assets $ 1,323,785 $ 1,296,029 December 31, 2014 (U.S. dollars in thousands) Amortized Fair Value Fixed maturities - Trading - Life Funds Withheld Assets Corporate - Non Financials $ 1,180 $ 1,171 Total investments - Trading - Life Funds Withheld Assets $ 1,180 $ 1,171 At December 31, 2015 and 2014 , approximately 2.0% and 3.0% , respectively, of the Company's fixed income investment portfolio at fair value, excluding Life Funds Withheld Assets, was invested in securities that were below investment grade or not rated. Approximately 14.7% and 24.9% of the gross unrealized losses in the Company's fixed income investment portfolio, excluding Life Funds Withheld Assets, at December 31, 2015 and 2014 , respectively, related to securities that were below investment grade or not rated. Contractual Maturities Summary The contractual maturities of AFS and Trading fixed income securities at December 31, 2015 and 2014 are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (U.S. dollars in thousands) December 31, 2015 December 31, 2014 Amortized Cost Fair Value Amortized Cost Fair Value Fixed maturities - AFS - Excluding Life Funds Withheld Assets Due less than one year $ 2,106,851 $ 2,104,106 $ 1,972,224 $ 1,980,429 Due after 1 through 5 years 14,051,494 14,143,461 8,919,037 9,113,651 Due after 5 through 10 years 5,680,830 5,740,954 4,232,396 4,412,569 Due after 10 years 1,374,997 1,423,156 1,494,315 1,705,022 $ 23,214,172 $ 23,411,677 $ 16,617,972 $ 17,211,671 RMBS – Agency $ 3,697,756 $ 3,757,971 $ 3,625,171 $ 3,728,576 RMBS – Non-Agency 319,876 328,540 404,398 427,351 CMBS 401,713 405,316 1,033,819 1,052,544 CDO 41,679 32,410 717,544 692,034 Other asset-backed securities 1,164,426 1,168,572 1,028,528 1,065,293 Total mortgage and asset-backed securities $ 5,625,450 $ 5,692,809 $ 6,809,460 $ 6,965,798 Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 28,839,622 $ 29,104,486 $ 23,427,432 $ 24,177,469 Fixed maturities - AFS - Life Funds Withheld Assets Due less than one year $ 81,700 $ 92,921 $ 117,048 $ 125,326 Due after 1 through 5 years 386,810 416,743 638,526 685,787 Due after 5 through 10 years 491,621 558,805 1,004,698 1,165,348 Due after 10 years 1,452,267 1,784,653 2,059,637 2,649,279 $ 2,412,398 $ 2,853,122 $ 3,819,909 $ 4,625,740 RMBS – Agency $ 591 $ 752 $ 3,301 $ 3,782 RMBS – Non-Agency 24,401 26,953 71,075 85,335 CMBS 107,968 122,481 168,886 193,167 Other asset-backed securities 132,674 149,795 238,168 273,541 Total mortgage and asset-backed securities $ 265,634 $ 299,981 $ 481,430 $ 555,825 Total fixed maturities - AFS - Life Funds Withheld Assets $ 2,678,032 $ 3,153,103 $ 4,301,339 $ 5,181,565 Total fixed maturities - AFS $ 31,517,654 $ 32,257,589 $ 27,728,771 $ 29,359,034 (U.S. dollars in thousands) December 31, 2015 December 31, 2014 Amortized Cost Fair Value Amortized Cost Fair Value Fixed maturities - Trading - Life Funds Withheld Assets Due less than one year $ 4,573 $ 5,096 $ — $ — Due after 1 through 5 years 278,163 272,220 — — Due after 5 through 10 years 280,487 277,920 1,180 1,171 Due after 10 years 668,737 649,592 — — $ 1,231,960 $ 1,204,828 $ 1,180 $ 1,171 RMBS – Agency 370 368 — — CMBS 4,874 4,803 — — Other asset-backed securities 26,405 25,700 — — Total mortgage and asset-backed securities 31,649 30,871 — — Total fixed maturities - Trading - Life Funds Withheld Assets $ 1,263,609 $ 1,235,699 $ 1,180 $ 1,171 Pledged Assets Certain of the Company's invested assets are held in trust and pledged in support of insurance and reinsurance liabilities as well as to collateralize our credit facilities. Such pledges are largely required by the Company's operating subsidiaries that are "non-admitted" under U.S. state insurance regulations, in order for the U.S. cedant to receive statutory credit for reinsurance. Also included in pledged assets are Life Funds Withheld Assets as noted in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ." Additionally, certain deposit liabilities and annuity contracts require the use of pledged assets. As of December 31, 2015 and December 31, 2014 , the Company had $18.3 billion and $15.2 billion in pledged assets, respectively. (b) Gross Unrealized Losses The following is an analysis of how long the AFS securities at December 31, 2015 and 2014 had been in a continual unrealized loss position: December 31, 2015 (U.S. dollars in thousands) Less than 12 months Equal to or greater than 12 months Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities and short-term investments - AFS U.S. Government and Government-Related/Supported $ 3,762,869 $ (29,339 ) $ 89,113 $ (5,044 ) Corporate - Financials 1,641,021 (13,280 ) 102,022 (10,192 ) Corporate - Non Financials 3,275,270 (73,069 ) 227,527 (24,706 ) RMBS – Agency 1,065,055 (10,046 ) 221,211 (7,515 ) RMBS – Non-Agency 19,614 (1,104 ) 180,146 (15,876 ) CMBS 118,605 (1,561 ) 78,651 (2,769 ) CDO 12,311 (516 ) 20,096 (8,757 ) Other asset-backed securities 572,671 (5,252 ) 57,563 (8,268 ) U.S. States and political subdivisions of the States 565,055 (6,609 ) 12,259 (765 ) Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 1,921,286 (53,440 ) 474,929 (46,714 ) Total fixed maturities and short-term investments - AFS $ 12,953,757 $ (194,216 ) $ 1,463,517 $ (130,606 ) Total equity securities $ 356,742 $ (45,153 ) $ — $ — Less than 12 months Equal to or greater than 12 months December 31, 2014 (U.S. dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Fixed maturities and short-term investments - AFS U.S. Government and Government-Related/Supported $ 251,091 $ (1,196 ) $ 342,890 $ (5,603 ) Corporate – Financials 387,619 (5,858 ) 105,155 (7,097 ) Corporate – Non Financials 949,851 (28,023 ) 319,066 (8,657 ) RMBS – Agency 134,535 (220 ) 512,652 (10,563 ) RMBS – Non-Agency 45,378 (1,358 ) 202,700 (16,797 ) CMBS 78,356 (385 ) 169,065 (4,877 ) CDOs 249,803 (2,666 ) 414,516 (24,503 ) Other asset-backed securities 143,044 (2,813 ) 57,544 (3,232 ) U.S. States and political subdivisions of the States 32,187 (210 ) 63,695 (994 ) Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 624,346 (19,043 ) 558,422 (43,251 ) Total fixed maturities and short-term investments - AFS $ 2,896,210 $ (61,772 ) $ 2,745,705 $ (125,574 ) Total equity securities $ 191,193 $ (26,230 ) $ — $ — The Company had gross unrealized losses totaling $370.0 million on 3,248 securities out of a total of 8,729 held at December 31, 2015 in its AFS Excluding Life Funds Withheld Assets portfolio, which either it considers to be temporarily impaired or with respect to which it reflects non-credit losses on other-than-temporarily impaired assets. Individual security positions comprising this balance have been evaluated by management to determine the severity of these impairments and whether they should be considered other-than-temporary. Management believes it is more likely than not that the issuer will be able to fund sufficient principal and interest payments to support the current amortized cost. (c) Net Investment Income Net investment income for the years ended December 31 is derived from the following sources: (U.S. dollars in thousands) 2015 2014 2013 Fixed maturities, short term investments and cash equivalents - Excluding Life Funds Withheld Assets $ 726,161 $ 809,964 $ 982,275 Fixed maturities, short term investments and cash equivalents - Life Funds Withheld Assets 187,489 129,575 — Equity securities and other investments 28,200 42,252 35,388 Interest on funds withheld 10,835 14,583 12,783 Total gross investment income $ 952,685 $ 996,374 $ 1,030,446 Investment expenses (80,315 ) (77,749 ) (72,730 ) Total net investment income $ 872,370 $ 918,625 $ 957,716 (d) Net Realized Gains (Losses) The following represents an analysis of net realized gains (losses), the change in unrealized gains (losses) on investments and net realized and unrealized gains (losses) on investment related derivative instruments for the years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Fixed maturities, short term investments, cash and cash equivalents - Excluding Life Funds Withheld Assets: Gross realized gains $ 187,523 $ 119,817 $ 129,479 Gross realized losses on investments sold (134,441 ) (66,892 ) (84,703 ) OTTI on investments, net of amounts transferred to other comprehensive income (54,346 ) (12,341 ) (16,282 ) Net realized gains (losses) $ (1,264 ) $ 40,584 $ 28,494 Equity securities: Gross realized gains $ 79,556 $ 96,260 $ 29,402 Gross realized losses on investments sold (49,223 ) (12,270 ) (3,185 ) OTTI on investments, net of amounts transferred to other comprehensive income (15,954 ) (10,944 ) (17 ) Net realized gains (losses) $ 14,379 $ 73,046 $ 26,200 Other investments: Gross realized gains $ 39,198 $ 31,830 $ 46,934 Gross realized losses on investments sold (19,656 ) (10,011 ) (13,851 ) OTTI on investments, net of amounts transferred to other comprehensive income (12,660 ) (12,458 ) — Net realized gains (losses) $ 6,882 $ 9,361 $ 33,083 Net realized gains (losses) on investments - Excluding Life Funds Withheld Assets $ 19,997 $ 122,991 $ 87,777 Fixed maturities, short term investments, cash and cash equivalents - Life Funds Withheld Assets: Gross realized gains $ 259,798 $ 7,926 $ — Gross realized losses on investments sold (36,526 ) (2,859 ) — Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets (27,734 ) (9 ) — OTTI on investments, net of amounts transferred to other comprehensive income (13,357 ) (20,587 ) — Net realized gains (losses) on investments - Life Funds Withheld Assets $ 182,181 $ (15,529 ) $ — Net realized gains (losses) on investments $ 202,178 $ 107,462 $ 87,777 Net realized and unrealized gains (losses) on investment related derivative instruments $ (8,616 ) $ 20,121 $ 6,367 Net realized gains (losses) on investments and net realized and unrealized gains (losses) on investment related derivative instruments $ 193,562 $ 127,583 $ 94,144 Change in unrealized gains (losses): Fixed maturities – AFS - Excluding Life Funds Withheld Assets $ (486,140 ) $ 360,463 $ (913,174 ) Fixed maturities - AFS - Life Funds Withheld Assets (405,155 ) 880,226 — Fixed maturities – HTM — (272,540 ) (175,817 ) Equity securities (59,619 ) (32,577 ) 105,163 Affiliates and other investments (6,072 ) 35,143 26,636 Net change in unrealized gains (losses) on investments $ (956,986 ) $ 970,715 $ (957,192 ) Total net realized gains (losses) on investments, net realized and unrealized gains (losses) on investment related derivative instruments, and net change in unrealized gains (losses) on investments $ (763,424 ) $ 1,098,298 $ (863,048 ) The significant components of OTTI charges of $83.0 million , as defined in Note 2(g), "Significant Accounting Policies - Other-Than-Temporary Impairments of Available for Sale ," for investments excluding Life Funds Withheld Assets for the year ended December 31, 2015 were: ▪ $19.4 million related to change of intent to hold Corporate high yield securities. ▪ $16.0 million related to certain equities that were in a loss position for more than 11 months or impaired by more than 50%. ▪ $8.7 million related to other investments. ▪ $8.0 million for structured securities, principally CDOs that we no longer intend to hold for a period sufficient to recover their fair value to amortized cost. ▪ $4.0 million related to hedge funds, included in other investments, that were in a loss position for more than 11 months. ▪ $2.0 million related to certain quasi-government securities that we no longer intend to hold for a period sufficient to recover their fair value to amortized cost. ▪ $1.3 million for structured securities, principally non-Agency RMBS, where we determined that the likely recovery on these securities was below the carrying value and, accordingly, recorded an impairment of the securities to the discounted value of the cash flows expected to be received on these securities. ▪ $23.6 million related to foreign exchange losses. The significant components of OTTI charges of $35.7 million for investments excluding Life Funds Withheld Assets for the year ended December 31, 2014 were: ▪ $12.5 million related to other investments. ▪ $10.9 million related to certain equities as the holdings were in a loss position for more than 11 months or impaired by more than 50%. ▪ $3.7 million related to change of intent to hold certain Corporate high yield securities. ▪ $4.3 million for structured securities, principally non-Agency RMBS, where we determined that the likely recovery on these securities was below the carrying value and, accordingly, recorded an impairment of the securities to the discounted value of the cash flows expected to be received on these securities. ▪ $4.3 million related to foreign exchange losses. The following table sets forth the amount of credit loss impairments on fixed income securities, for which a portion of the OTTI loss was recognized in OCI, held by the Company as of the dates or for the periods indicated and the corresponding changes in such amounts. Credit Loss Impairments (U.S. dollars in thousands) 2015 2014 Opening balance at beginning of indicated period $ 131,942 $ 174,805 Credit loss impairment recognized in the current period on securities not previously impaired 9,698 3,907 Credit loss impairments previously recognized on securities which matured, paid down, prepaid or were sold during the period (54,648 ) (42,671 ) Credit loss impairments previously recognized on securities impaired to fair value during the period (2,629 ) — Additional credit loss impairments recognized in the current period on securities previously impaired 2,230 4,185 Accretion of credit loss impairments previously recognized due to an increase in cash flows expected to be collected (13,124 ) (8,284 ) Closing balance at end of indicated period $ 73,469 $ 131,942

Investments in Affiliates

Investments in Affiliates	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments in affiliates	Investments in Affiliates Investments in affiliates comprised the following at December 31, 2015 and 2014 . See Note 2(c), "Significant Accounting Policies - Total Investments - Investments in Affiliates," for a description of our accounting policy for these assets: (U.S. dollars in thousands) 2015 2014 Investment fund affiliates $ 1,386,837 $ 1,219,138 Operating affiliates 322,062 418,482 Total investment affiliates $ 1,708,899 $ 1,637,620 (a) Investment Fund Affiliates The Company has invested in certain hedge funds, including funds managed by certain of its investment manager affiliates, and in certain private equity and private credit funds (collectively, "private investment funds") that are accounted for under the equity method due to our ownership percentages in the limited partnerships, LLCs or other similar investment vehicles that form the funds. Collectively, these investments in hedge funds and private investment funds are classified as "investment fund affiliates." At December 31, 2015 and 2014 , the hedge fund portfolio, accounted for as hedge fund affiliates, employed four strategies. The Company’s equity investment in investment fund affiliates and equity in net income (loss) from such affiliates as well as certain summarized financial information of the investee on a combined basis (shown as "Combined Funds") are included below: Year Ended December 31, 2015 (U.S. dollars in thousands, except percentages) XL Group Investment Combined Carrying Equity in Weighted Total Net Assets Hedge Funds: Arbitrage $ 190,016 $ 612 8.6 % $ 2,202,112 Directional 551,262 31,012 7.2 % 7,643,134 Event Driven (2) 285,823 5,592 3.0 % 9,460,387 Multi-Style 57,097 5,452 3.6 % 1,600,959 Total hedge funds $ 1,084,198 $ 42,668 5.2 % $ 20,906,592 Private Investment Funds: 302,639 30,652 9.5 % 3,195,204 Total Investment Fund Affiliates $ 1,386,837 $ 73,320 5.8 % $ 24,101,796 Year Ended December 31, 2014 Hedge Funds: Arbitrage $ 134,400 $ 12,060 11.0 % $ 1,224,526 Directional 536,470 32,196 9.2 % 5,865,247 Event Driven (2) 300,168 21,030 3.1 % 9,703,973 Multi-Style 52,122 1,751 4.1 % 1,278,410 Total hedge funds $ 1,023,160 $ 67,037 5.7 % $ 18,072,156 Private Investment Funds: 195,978 28,779 17.7 % 1,105,776 Total Investment Fund Affiliates $ 1,219,138 $ 95,816 6.4 % $ 19,177,932 ____________ (1) Total estimated net assets are generally as at November 30 for hedge fund affiliates and September 30 for private investment fund affiliates. (2) The Company accounts for its investment in certain funds where the ownership percentage is less than three percent using the equity method, where the Company has significant influence over the related investment management company. In general, the hedge funds in which the Company is invested require at least 30 days notice of redemption, and may be redeemed on a monthly, quarterly, semi-annual, annual or longer basis, depending on the fund. Certain hedge funds have a lock-up period and/or may also have the ability to impose a redemption gate. A lock-up period refers to the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. Typically, the imposition of a gate delays a portion of the requested redemption, with the remaining portion settled in cash shortly after the redemption date. The carrying value of the Company’s holdings in hedge fund affiliates that are subject to lockups and/or that have gate provisions in their governing documents at December 31, 2015 and 2014 was $382.0 million and $543.0 million , respectively. Certain hedge funds may be allowed to invest a portion of their assets in illiquid securities, such as private equity or private debt. In such cases, a common mechanism used is a side-pocket, whereby the illiquid security is assigned to a separate memorandum capital account or other designated account. Typically, the investor loses its redemption rights in the designated account. Only when the illiquid securities in the side-pocket are sold, or otherwise deemed liquid by the fund, may investors redeem that portion of their interest that has been "side-pocketed." At December 31, 2015 and 2014 , the carrying value of our hedge fund affiliates held in side-pockets was $18.2 million and $22.2 million , respectively. The underlying assets within these positions are generally expected to be liquidated over a period of approximately two to four years. (b) Operating Affiliates The Company has invested in strategic (re)insurance affiliates and investment management companies’ securities or other forms of direct ownership interests across the capital structure. Collectively, these investments are classified as "operating affiliates." The Company’s equity investment in operating affiliates and equity in net income (loss) from such affiliates as well as certain summarized financial information of the investee as a whole are included below: Year ended December 31, 2015 (U.S. dollars in thousands) XL Group Investment Combined Investee Summarized Carrying Equity in Total Total Total Net Income Strategic and other operating affiliates $ 251,348 $ 33,608 $ 4,280,976 $ 3,293,873 $ 847,131 $ 91,701 Investment manager affiliates (1) 70,714 11,132 708,605 95,826 206,672 90,491 Total operating affiliates $ 322,062 $ 44,740 $ 4,989,581 $ 3,389,699 $ 1,053,803 $ 182,192 Year ended December 31, 2014 Strategic and other operating affiliates 317,216 50,132 4,679,395 3,691,173 1,075,935 152,122 Investment manager affiliates (1) 101,266 57,086 850,666 101,088 579,524 476,841 Total operating affiliates $ 418,482 $ 107,218 $ 5,530,061 $ 3,792,261 $ 1,655,459 $ 628,963 ____________ (1) During the years ended December 31, 2015 and 2014 , the Company received distributions from its Investment Manager Affiliates of approximately $25.3 million and $60.3 million , respectively. (2) Total assets and total liabilities reflect balances related to investees still held at December 31, 2015 and 2014 , respectively. Total revenue (loss) and net income (loss) reflect activity for the years ended December 31, 2015 and 2014 related to both investees still held at year-end and investees disposed of during the year. In certain investments, the carrying value is different from the share of the investee’s underlying net assets. The differences represent goodwill on acquisition, OTTI recorded with respect to the investment, or differences in the retained capital accounts of the various equity holders (including the Company). See Note 17(c), "Commitments and Contingencies - Investments in Affiliates ," for further information regarding commitments related to investment in affiliates. Strategic and Other Operating Affiliates At December 31, 2015 , the Company’s larger strategic and other operating affiliates included Privilege Underwriters, Inc. and its affiliates ("PURE Group"), Westaim HIIG LP ("Westaim HIIG"), Five Oaks Investment Corp ("Five Oaks") and CATGS I, LLC. On December 15, 2014, the Company announced it had entered into a Stock Purchase Agreement to sell its interests in one of its largest strategic and other operating affiliates, ARX, to The Progressive Corporation ("Progressive"). For further information, see Note 3(d), "Acquisitions and Disposals - Sale of Operating Affiliate ." In the fourth quarter of 2015, the Company made investments totaling $102.5 million related to the PURE Group, an insurance provider specializing in products for high net worth individuals. The PURE Group investments consisted of: (i) a $77.5 million purchase of 9.9% of the ordinary common units and preferred units of Privilege Group Holdings LP, and 9.9% of the units of Privilege Group Holdings GP, LLC; and (ii) a $25.0 million purchase, at par value, of a ten year surplus note issued by Privilege Underwriters Reciprocal Exchange. Under the terms of an agreement between the parties, the PURE Group has the option to require the Company to purchase up to $50.0 million of additional ten year surplus notes, at par, over a commitment period expiring no later than November 2020. The Company has an investment of $32.7 million , representing 13.1% ownership in Westaim HIIG. The primary purpose of Westaim HIIG is to invest in interests of Houston International Insurance Group ("HIIG"), a specialty insurance provider. Westaim HIIG holds a majority interest of the common stock of HIIG. The Company has an investment of $33.2 million , representing 21.9% ownership in Five Oaks, a mortgage real estate investment trust that is focused on investing in, financing and managing a leveraged portfolio of agency and non-agency residential mortgage-backed securities, residential mortgage loans and other mortgage-related investments. In addition, Company holds warrants to purchase an additional 3.125 million shares at $15.75 per share, which would result in a total additional investment of $49.2 million by the Company should it exercise the warrants in full in the future. The warrants expire in September 2019. The Company has an investment of $22.1 million , representing 50.0% ownership in CATGS I, LLC. The remaining 50.0% is held by on other investor. The Company does not control the entity, whose primary purpose is the purchase and leasing of equipment. Investment Manager Affiliates During the years ended December 31, 2015, 2014 and 2013 , the Company’s larger investment manager affiliates included Highfields Capital, a global equity investment firm, and Polar Capital, an investment firm offering traditional and alternative products.

Other Investments

Other Investments	12 Months Ended
	Dec. 31, 2015
Investments, All Other Investments [Abstract]
Other investments	Other Investments Other investments comprised the following at December 31, 2015 and 2014 . See Note 2(c), "Significant Accounting Policies - Total Investments - Other Investments," for a description of our accounting policy for these assets: Year ended December 31, (U.S. dollars in thousands) 2015 2014 Hedge Funds: Arbitrage $ 205,117 $ 179,821 Directional 276,277 336,082 Event Driven 5,427 56,238 Multi-Style 57,249 68,706 Total hedge funds $ 544,070 $ 640,847 Private investment funds 244,576 129,243 Overseas deposits 479,187 92,223 Structured transactions 138,608 350,563 Other 26,616 35,563 Total other investments $ 1,433,057 $ 1,248,439 (a) Hedge Funds and Private Investment Funds At December 31, 2015 and 2014 , the hedge fund portfolio, accounted for as other investments, employed four strategies. In general, the funds in which the Company is invested require at least 30 days notice of redemption, and may be redeemed on a monthly, quarterly, semi-annual, annual or longer basis, depending on the fund. Certain hedge funds have a lock-up period and/or may also have the ability to impose a redemption gate. A lock-up period refers to the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. Typically, the imposition of a gate delays a portion of the requested redemption, with the remaining portion settled in cash shortly after the redemption date. The fair value of the Company’s holdings in hedge funds that may be subject to lockups and/or that have gate provisions in their governing documents at December 31, 2015 and 2014 was $399.6 million and $425.7 million , respectively. The Company did not have any holdings in funds where a gate was imposed at December 31, 2015 or 2014 . Certain hedge funds may be allowed to invest a portion of their assets in illiquid securities, such as private equity or private debt. In such cases, a common mechanism used is a side-pocket, whereby the illiquid security is assigned to a separate memorandum capital account or other designated account. Typically, the investor loses its redemption rights in the designated account. Only when the illiquid securities in the side-pocket are sold, or otherwise deemed liquid by the fund, may investors redeem that portion of their interest that has been "side-pocketed". At December 31, 2015 and 2014 , the fair value of hedge funds held in side-pockets was $26.0 million and $24.5 million , respectively. The underlying assets within these positions are generally expected to be liquidated over a period of approximately two to four years . The following represents an analysis of the net realized gains for the indicated years ended December 31, and the net unrealized gains as of December 31, on the Company’s hedge funds and private investment funds: Year ended December 31, (U.S. dollars in thousands) Net Unrealized Gains Net Realized Gains (Losses) 2015 2014 2015 2014 2013 Hedge funds $ 188,698 $ 188,674 $ 12,769 $ 6,685 $ 30,858 Private investment funds 38,340 42,604 9,342 13,275 4,331 Total $ 227,038 $ 231,278 $ 22,111 $ 19,960 $ 35,189 (b) Overseas Deposits Overseas deposits include investments in private funds related to Lloyd’s syndicates in which the underlying instruments are primarily government and government-related/supported and corporate fixed income securities. The funds themselves do not trade on an exchange and therefore are not included within available for sale securities. Also included in overseas deposits are restricted cash and cash equivalent balances held by Lloyd’s syndicates for solvency purposes. Given the restricted nature of these cash balances, they are not included within the cash and cash equivalents category in the balance sheets. (c) Structured Transactions National Indemnity Endorsement On June 9, 2009, XL Specialty Insurance Company ("XL Specialty"), a wholly-owned subsidiary of the Company, entered into an agreement with National Indemnity Company, an insurance company subsidiary of Berkshire Hathaway Inc. ("National Indemnity"). Under the agreement, and a related reinsurance agreement, National Indemnity agreed to issue endorsements to certain directors and officers liability insurance policies known as "Side A" coverage policies underwritten by XL Specialty (the "Facility") during an eighteen month period that ended in December 31, 2011. In connection with the Facility, XLIB purchased a payment obligation (the "Obligation") in an aggregate principal amount of $150.0 million from National Indemnity. The outstanding Obligation was recorded in other investments at an estimated fair value of $128.1 million , pays a coupon of 3.5% , and is being accreted to $150.0 million over the 11.5 years term of the payment obligation. The difference between the estimated fair value of the Obligation and the cost of that Obligation at the time of the transaction was approximately $21.9 million and was recorded in Other Assets. This difference, together with fees of $2.5 million , was amortized in relation to the earning of the underlying policies written. Other Structured Transactions On July 17, 2009, XLIB purchased notes with an aggregate face amount of $155.0 million . The carrying value of these notes at December 31, 2014 was $136.0 million . On October 29, 2014, XLIB, a wholly-owned subsidiary of the Company, purchased notes with an aggregate face amount of $81.9 million . The carrying value of these notes at December 31, 2014 was $77.8 million . The issuer of both series of notes is a structured credit vehicle that holds corporate debt and preferred equity securities, including some securities issued by European financial institutions, as well as project finance debt securities, among other assets. During the years ended December 31, 2015 and 2014 , the Company recorded losses of $8.6 million and $12.5 million , respectively, due to other than temporary declines in value of these investments. During the fourth quarter of 2015, XLIB entered into transactions whereby it acquired the underlying corporate debt and preferred equity securities in return for the cancellation of the notes. The newly acquired securities are included in our available for sale fixed maturities and equity securities portfolios. In connection with the cancellation of the notes, the Company recorded realized investment losses of $6.7 million . These structured transactions were not required to be measured at fair value under GAAP and, accordingly, they have been excluded from the fair value measurement disclosures at December 31, 2014 . See Note 4, "Fair Value Measurements ," for details surrounding the estimated fair value of these investments. See Note 17(b), "Commitments and Contingencies - Other Investments ," for further information regarding commitments related to other investments.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	Goodwill and Other Intangible Assets The following table presents an analysis of intangible assets broken down between goodwill, intangible assets with an indefinite life and intangible assets with a definite life for the years ended December 31, 2015, 2014 and 2013 : (U.S. dollars in thousands) Goodwill Intangible assets with an indefinite life Intangible assets with a definite life Total Balance at December 31, 2012 $ 392,882 $ 15,366 $ 279 $ 408,527 Amortization — — (279 ) (279 ) Foreign currency translation 3,363 — — 3,363 Balance at December 31, 2013 $ 396,245 $ 15,366 $ — $ 411,611 Additions 25,159 — 18,500 43,659 Amortization — — (1,850 ) (1,850 ) Foreign currency translation (5,468 ) — — (5,468 ) Balance at December 31, 2014 $ 415,936 $ 15,366 $ 16,650 $ 447,952 Additions 807,381 673,000 315,000 1,795,381 Amortization — — (15,517 ) (15,517 ) Foreign currency translation (9,687 ) (5,507 ) (2,356 ) (17,550 ) Balance at December 31, 2015 $ 1,213,630 $ 682,859 $ 313,777 $ 2,210,266 Goodwill At December 31, 2015 and 2014 , the Company had goodwill of $1.2 billion and 415.9 million , respectively. At December 31, 2015 , $479.5 million and $734.2 million were allocated to the Insurance and Reinsurance segments, respectively. The entire balance of $415.9 million at December 31, 2014 was allocated to the Reinsurance segment. In the third quarter of 2015, as a result of the transaction described in Note 3(b), "Acquisitions and Disposals - New Energy Risk ," the Company recognized additional goodwill of approximately $13.4 million . The transaction was accounted for using the acquisition method under which the Company recorded the identifiable assets acquired and liabilities assumed at their acquisition date fair values, and recorded as goodwill the excess of the sum of a) over b) - in which a) represents the aggregate of: i) the consideration transferred, ii) the fair value of noncontrolling interest in the acquiree, and iii) the acquisition-date fair value of the Company's previously held equity interest in the acquiree; and b) represents the net assets acquired in the transaction. In the second quarter of 2015, as a result of the transaction described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," the Company recognized additional goodwill and other intangible assets. The transaction was accounted for using the acquisition method under which the Company recorded the identifiable assets acquired, including indefinite-lived and definite-lived intangible assets, and liabilities assumed, at their Acquisition Date fair values, and recorded the excess of consideration transferred over the net assets acquired as goodwill. During the first quarter of 2014, Goodwill and Other Intangible Assets increased as a result of the completion of an acquisition. The transaction was accounted for using the acquisition method under which the Company recorded the identifiable assets and liabilities at their acquisition date fair values, and recorded the excess of consideration transferred over the net assets acquired as goodwill and intangible assets. The fair value of identifiable assets and liabilities acquired, as well as amounts recorded in the Company’s consolidated results since the acquisition date, are not material. The estimated fair values of the reporting units’ carried goodwill exceeded their estimated net book values at December 31, 2015 , and therefore no impairments were recorded during 2015 . At December 31, 2015 and 2014 , the ending goodwill balance is comprised of gross goodwill of $2.6 billion and $1.8 billion , respectively, offset by accumulated impairment charges of $1.4 billion at December 31, 2015 and 2014 . For further details regarding our impairment process, see Note 2(k), "Significant Accounting Policies - Goodwill, Intangibles and Other Long-Lived Assets ." Other Intangible Assets At December 31, 2015 and 2014 , the ending definite-lived intangible assets balance is comprised of $333.5 million and $18.5 million , respectively, of gross intangible assets, offset by accumulated amortization of $17.4 million and $1.9 million , respectively. Future amortization expenses are expected to be as follows: Year Ended December 31, 2016 $ 22,350 2017 19,017 2018 17,350 2019 17,350 2020 17,350 2021-2036 220,360 Total expected amortization expenses $ 313,777 The following table summarizes the intangible assets and their related useful lives recorded in connection with the Catlin Acquisition, as described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," as of the Acquisition Date: (U.S. dollars in thousands) Amount Estimated Useful Life Lloyd's - Syndicate capacity $ 660,000 Indefinite Insurance licenses 13,000 Indefinite Total identified indefinite life intangible assets $ 673,000 Lloyd's - Managing agent contracts 15,000 15 years Distribution network 290,000 20 years Trademarks / Trade names 10,000 2 years Total identified definite life intangible assets $ 315,000 Total identified intangible assets $ 988,000 An explanation of the intangible assets is as follows: • Lloyd's syndicate capacity - This asset represents the syndicate capacity of two Lloyd's syndicates allowing the Company to write insurance business in the Lloyd's market globally and realize the profits from that business. The value of the syndicate capacity includes the reputational value of participation in the Lloyd's market, and the value of trade names and licenses associated with syndicate ownership. The syndicate capacity was valued using the Multi-Period Excess Earnings Method, an application of the Income Approach. Critical inputs into the valuation model used for this intangible included estimates of the future growth of syndicate authorized premium income limits (ie, capacity) and expected return on that capacity and discounting based on a weighted average cost of capital. • Insurance licenses - The insurance licenses owned by Catlin at the time of the Catlin Acquisition allow the Company to write insurance business in the United States. The insurance licenses were valued using the Market Approach. Critical inputs utilized in the valuation of this intangible were the number of licenses obtained by US state and an aggregate market value per license based on similar past market transactions. • Lloyd's managing agent contracts - As the managing agent for certain Lloyd's syndicates, the Company has contracts with the syndicate members to provide underwriting services for which it earns managing agent fees and a profit commission. The managing agent contracts were based on the Income Approach. Critical inputs utilized in the valuation of this intangible included expected contract fee and profit commission rates applied to future managed syndicate capacity, contract renewal probabilities over a time horizon and discounting based on a weighted average cost of capital. • Distribution network - This asset represents a network of hundreds of retail and wholesale brokers worldwide, including specialty and regional brokerages, which allow the Company to form closer relationships with clients and aids business retention. The distribution network was valued using the Multi-Period Excess Earnings Method, an application of the Income Approach. Critical inputs into the valuation model used for this intangible included projections of underwriting profitability and investment returns, supporting capital charges, and discounting based on a weighted average cost of capital. • Trademarks / Trade names - The Catlin trademarks / trade names are utilized to attract customers for the turnkey solutions provided under the Company's managing agent contracts and to generate premiums from the non-Lloyd's platform underwriting products for which the Catlin brand is known. The trademarks and trade names were based on the Relief-from-Royalty Method, an application of the Income Approach. Critical inputs used in the valuation of this intangible included industry-based market royalty rates on premium revenues to be generated through use of the trademarks/trade names, expected useful life over which the company expects to co-brand under the trademarks/trade names and discounting based on a weighted average cost of capital.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2015
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The Company utilizes reinsurance and retrocession agreements principally to increase aggregate capacity and to reduce the risk of loss on business assumed. The Company’s reinsurance and retrocession agreements provide for recovery of a portion of losses and loss expenses from reinsurers, and reinsurance recoverables are recorded as assets. The Company is liable if the reinsurers are unable to satisfy their obligations under the agreements. Under its reinsurance security policy, the Company seeks to cede business to reinsurers generally with a financial strength rating of "A" or better. The Company considers reinsurers that are not rated or do not fall within the above rating categories and may grant exceptions to the Company’s general policy on a case-by-case basis. The effect of reinsurance and retrocessional activity on premiums written and earned from property and casualty operations is shown below: (U.S. dollars in thousands) Premiums Written Year Ended December 31, Premiums Earned Year Ended December 31, 2015 2014 2013 2015 2014 2013 Direct $ 7,847,236 $ 5,450,868 $ 5,050,953 $ 7,717,173 $ 5,173,403 $ 4,966,207 Assumed 2,821,771 2,310,621 2,365,839 3,465,421 2,343,329 2,363,261 Ceded (2,780,183 ) (1,994,280 ) (1,512,810 ) (3,018,410 ) (1,799,294 ) (1,315,369 ) Net $ 7,888,824 $ 5,767,209 $ 5,903,982 $ 8,164,184 $ 5,717,438 $ 6,014,099 The Company recorded reinsurance recoveries on losses and loss expenses incurred of $1.6 billion , $0.7 billion and $0.7 billion for the years ended December 31, 2015, 2014 and 2013 , respectively. The following table presents an analysis of total unpaid losses and loss expenses recoverable for the years ended December 31: (U.S. dollars in thousands) 2015 2014 P&C Operations $ 5,248,905 $ 3,411,528 Corporate and Other 13,801 17,840 Total unpaid losses and loss expenses recoverable $ 5,262,706 $ 3,429,368 The table above excludes a combined $3.7 billion and $0.3 billion of the Company's future policy benefit reserve recoverables under the GreyCastle Life Retro Arrangements and U.S. Term Life Retro Arrangements, as defined in Note 13, "Future Policy Benefit Reserves ," respectively, and are also excluded from the remainder of this disclosure. At December 31, 2015 and 2014 , the total reinsurance assets of $5.7 billion and $3.6 billion , respectively, included reinsurance receivables for paid losses and loss expenses of $418.7 million and $131.5 million , respectively, with $5.3 billion and $3.4 billion relating to the ceded reserve for losses and loss expenses, including ceded losses incurred but not reported for each year end. Although the contractual obligation of individual reinsurers to pay their reinsurance obligations is based on specific contract provisions, the collectibility of such amounts requires significant estimation by management. The majority of the balance the Company has accrued as recoverable will not be due for collection until sometime in the future. Over this period of time, economic conditions and operational performance of a particular reinsurer may impact its ability to meet these obligations and, while it may continue to acknowledge its contractual obligation to do so, it may not have the financial resources or willingness to fully meet its obligations to the Company. At December 31, 2015 and 2014 , the allowance for uncollectible reinsurance relating to both reinsurance balances receivable and unpaid losses and loss expenses recoverable was $82.1 million and $64.4 million , respectively. To estimate the provision for uncollectible reinsurance recoverable, the reinsurance recoverable must first be allocated to applicable reinsurers. As part of this process, ceded IBNR is allocated by reinsurer. The allocations are generally based on historical relationships between gross and ceded losses. If actual experience varies materially from historical experience, the allocation of reinsurance recoverable by reinsurer will change. The Company uses a default analysis to estimate uncollectible reinsurance recoverables. The primary components of the default analysis are reinsurance recoverable balances by reinsurer, net of collateral, and default factors used to determine the portion of a reinsurer’s balance deemed uncollectible. The definition of collateral for this purpose requires some judgment and is generally limited to assets held in trust, letters of credit, and liabilities held by the Company with the same legal entity for which the Company believes there is a right of offset. The Company is the beneficiary of letters of credit, trust accounts and funds withheld in the aggregate amount of $3.8 billion and $2.0 billion at December 31, 2015 and 2014 , respectively, collateralizing reinsurance recoverables with respect to certain reinsurers. Default factors require considerable judgment and are determined using the current financial strength rating, or rating equivalent, of each reinsurer as well as other key considerations and assumptions. The total allowance recorded relating to reinsurance recoverables was $58.2 million and $42.3 million at December 31, 2015 and 2014 , respectively. The Company uses an aging analysis to estimate uncollectible reinsurance balances receivable relating to paid losses in addition to recording allowances relating to any specific balances with known collectibility issues, irrespective of aging. The balances are aged from the date the expected recovery was billed to the reinsurer. Provisions are applied at specified percentages of the outstanding balances based upon the aging profile. Allowances otherwise required as a result of the aging process may not be recorded to the extent that specific facts and circumstances exist that lead management to believe that amounts will ultimately be collectible. The total allowance recorded relating to reinsurance balances receivable was $23.9 million and $22.1 million at December 31, 2015 and 2014 , respectively. At December 31, 2015 , the use of different assumptions within the model could have a material effect on the bad debt provision reflected in the Company’s Consolidated Financial Statements. To the extent the creditworthiness of the Company’s reinsurers was to deteriorate due to an adverse event affecting the reinsurance industry, such as a large number of major catastrophes, actual uncollectible amounts could be significantly greater than the Company’s bad debt provision. Such an event could have a material adverse effect on the Company’s financial condition, results of operations, and cash flows. At December 31, 2015 and 2014 , approximately 96% and 93% , respectively, of the total outstanding unpaid loss and loss expense recoverable and reinsurance balances receivable, net of collateral held, was due from reinsurers with a financial strength rating of "A" or better. The following is an analysis of the total recoverable and reinsurance balances receivable, net of collateral held, at December 31, 2015 , by reinsurers owing 3% or more of such total: Name of Reinsurer Reinsurer Financial Strength Rating % of Total Munich Reinsurance Co. AA-/Stable 26.1 % Lloyd's Syndicates A+/Stable 11.7 % Swiss Reinsurance Co. AA-/Stable 6.8 % Swiss Re Europe S.A. AA-/Stable 4.9 % Transatlantic Reinsurance Company A+/Stable 4.3 % Arch Reinsurance Company A+/Stable 3.0 % The following table sets forth the ratings profile of the reinsurers that support the unpaid loss and loss expense recoverable and reinsurance balances receivable, net of collateral, at December 31, 2015 : Reinsurer Financial Strength Rating % of Total AAA 3.0 % AA 45.8 % A 47.2 % BBB 0.5 % BB and below 0.7 % Captives 2.7 % Not Rated 0.1 % Total 100.0 %

Losses and Loss Expenses

Losses and Loss Expenses	12 Months Ended
	Dec. 31, 2015
Liability for Claims and Claims Adjustment Expense [Abstract]
Losses and loss expenses	Losses and Loss Expenses Unpaid losses and loss expenses for the indicated years ended December 31 are comprised of: (U.S. dollars in thousands) 2015 2014 Reserve for reported losses and loss expenses $ 10,293,448 $ 7,461,444 Reserve for losses incurred but not reported 15,146,296 11,891,799 Unpaid losses and loss expenses $ 25,439,744 $ 19,353,243 Net losses and loss expenses incurred for the years indicated are comprised of: (U.S. dollars in thousands) 2015 2014 2013 Loss and loss expenses payments $ 6,505,075 $ 4,499,642 $ 4,496,802 Change in unpaid losses and loss expenses (168,263 ) (514,406 ) (71,901 ) Change in unpaid losses and loss expenses recoverable (440,189 ) (48,536 ) (24,774 ) Paid loss recoveries (1,130,423 ) (678,307 ) (668,663 ) Net losses and loss expenses incurred $ 4,766,200 $ 3,258,393 $ 3,731,464 The following table represents an analysis of the Company’s paid and unpaid losses and loss expenses incurred and a reconciliation of the beginning and ending unpaid losses and loss expenses for the years indicated: (U.S. dollars in thousands) 2015 2014 2013 Unpaid losses and loss expenses at the beginning of the year $ 19,353,243 $ 20,481,065 $ 20,484,121 Unpaid losses and loss expenses recoverable 3,411,528 3,414,735 3,361,703 Net unpaid losses and loss expenses at the beginning of the year $ 15,941,715 $ 17,066,330 $ 17,122,418 Acquired reserves 5,439,876 — — Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in: Current year 5,072,830 3,513,465 4,021,353 Prior year (306,630 ) (255,072 ) (289,889 ) Total net incurred losses and loss expenses $ 4,766,200 $ 3,258,393 $ 3,731,464 Exchange rate effects (582,300 ) (561,673 ) 40,587 Less net losses and loss expenses paid in respect of losses occurring in: Current year 1,047,277 381,008 425,254 Prior year 4,327,375 3,440,327 3,402,885 Total net paid losses $ 5,374,652 $ 3,821,335 $ 3,828,139 Net unpaid losses and loss expenses at the end of the year 20,190,839 15,941,715 17,066,330 Unpaid losses and loss expenses recoverable 5,248,905 3,411,528 3,414,735 Unpaid losses and loss expenses at the end of the year $ 25,439,744 $ 19,353,243 $ 20,481,065 (a) Prior year net losses incurred The following table presents the net (favorable) adverse prior year loss development of the Company’s loss and loss expense reserves for its property and casualty operations by operating segment for each of the years indicated: (U.S. dollars in thousands) 2015 2014 2013 Insurance segment $ (65,030 ) $ (99,758 ) $ (102,039 ) Reinsurance segment (241,600 ) (155,314 ) (187,850 ) Total $ (306,630 ) $ (255,072 ) $ (289,889 ) The significant developments in prior year loss reserve estimates for each of the years indicated within the Company’s Insurance and Reinsurance segments are discussed below. Insurance Segment The following table summarizes the net (favorable) adverse prior year development by line of business relating to the Insurance segment for the indicated years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Professional $ 5,763 $ 17,097 $ 75,045 Casualty (11,949 ) 38,414 (21,829 ) Property 25,189 (57,470 ) (46,387 ) Specialty (120,879 ) (82,756 ) (140,740 ) Other 36,846 (15,043 ) 31,872 Total $ (65,030 ) $ (99,758 ) $ (102,039 ) Net favorable prior year development of $65.0 million for the Insurance segment for the year ended December 31, 2015 was attributable to the following: • For professional lines, net prior year development was $5.8 million unfavorable. Strengthening in the U.S. standard commercial and select accountants and public entities portfolios were largely offset by releases in the Bermuda standard commercial and design architects and engineers portfolios. • For casualty lines, net prior year development was $11.9 million favorable. This was driven by releases of $24.5 million in the excess casualty book, predominantly on the Bermuda portfolio, and $24.0 million in International casualty reflecting the better than expected loss experience reported across most accident years. These reductions were partially offset by deteriorations of $31.2 million in excess and surplus lines casualty book. • For property lines, net prior year development was $25.2 million unfavorable driven by worse than expected loss experience reported for the non-catastrophe exposures in the International construction and North America portfolios totaling $53.1 million . These deteriorations were partially offset by a reduction of $29.6 million in the International energy book to reflect better than expected attritional loss experience. • For specialty lines, net prior year development was $120.9 million favorable driven by releases of $60.8 million in the marine business and $18.8 million in the discontinued Bermuda political risk portfolio, the latter arising predominantly from the favorable settlement of a loss on the 2009 accident year and the lapse of the exposure for this account. There were further reductions of $14.8 million in the discontinued specialty book to reflect better than expected loss experience reported primarily on the 2002 and 2003 accident years and $15.2 million and $7.1 million to reflect favorable experience in aerospace and crisis management, respectively. • For other lines, net prior year development was $36.8 million unfavorable driven by a $25.4 million strengthening in the excess and surplus book due to worse than expected loss experience reported on the New York Contractors general liability business, predominantly on the 2013 and prior accident years. This was compounded by a strengthening of a $18.3 million in the surety book relating to a large claim impacting the 2013 and 2014 accident years. These deteriorations were partially offset by a $10.1 million reduction in the discontinued structured indemnity book due to the favorable settlement of a large claim. Net favorable prior year reserve development totaled $99.8 million for the Insurance segment for the year ended December 31, 2014 . Specialty benefited from a release in aerospace and the discontinued international political risk portfolio due to better than expected loss experience reported. Better than expected loss experience reported for the non-catastrophe exposures primarily in the 2013 accident year led to a release in property. Casualty experienced strengthenings in the U.S. environmental portfolio, Lloyd's middle market book and the U.S. primary casualty lines due to worse than expected loss experience from 2008 through 2013, while a strengthening in the core U.S. standard commercial book drove a strengthening in Professional. Net favorable prior year reserve development totaled $102.0 million for the Insurance segment for the year ended December 31, 2013 . Specialty benefited from releases in aerospace, marine and specie, due primarily to reflecting the better than expected loss experience reported predominantly across the 2005 and later accident years, plus a reduction in the Bermuda discontinued political risk book as a result of a review of the open claims and remaining exposure. Better than expected loss experience reported for non-catastrophe exposures primarily in the 2012 accident year led to a release in property, while casualty benefited from better than expected loss experience in the excess casualty book, partially offset by adverse development in the U.S. environmental book and worse than expected loss experience in the Lloyd's middle market book. Worse than expected loss experience in the U.S. standard commercial and international professional books led to a strengthening of reserves in professional, as well as deterioration in the discontinued environmental book impacting casualty and the discontinued surety book in other lines. There is no assurance that conditions and trends that have affected the development of liabilities in the past will continue. Accordingly, it may not be appropriate to extrapolate future redundancies or deficiencies based on the Company’s historical results. Reinsurance Segment The following table summarizes the net (favorable) adverse prior year development by line of business relating to the Reinsurance segment for the indicated years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Property and other short-tail lines $ (173,754 ) $ (85,324 ) $ (136,912 ) Casualty and other (67,846 ) (69,990 ) (50,938 ) Total $ (241,600 ) $ (155,314 ) $ (187,850 ) Net favorable prior year reserve development for the Reinsurance segment of $241.6 million for the year ended December 31, 2015 was attributable to the following: • Net favorable prior year development for the short-tailed lines totaled $173.8 million . Details of the significant components are as follows: ◦ For property catastrophe lines, net prior year development was $50.3 million favorable due to reductions on a number of catastrophe losses and better than expected development on attritional losses, mainly in Europe, Middle East & Africa ("EMEA") and Latin America & Credit. ◦ For property other lines, net prior year development was $88.9 million favorable primarily due to better than expected attritional loss development across all books. ◦ For specialty lines, net prior year development was $34.6 million favorable due to better than expected attritional loss development mainly in EMEA and reductions on catastrophe and large losses. • Net favorable prior year development for the long-tailed lines totaled $67.8 million . Details of the significant components are as follows: ◦ For casualty lines, net prior year development was $40.1 million favorable due to better than expected attritional loss development in London, EMEA and reductions on a 2001 and a 2009 large loss being partially offset by worse than expected attritional loss development in North America and a strengthening on two 2008 large losses. ◦ For other lines, net prior year development was $27.8 million favorable due to better than expected development on attritional losses mainly from whole account business written in Bermuda and London. Net favorable prior year reserve development totaled $155.3 million for the year ended December 31, 2014 . The short-tailed lines benefited from $63.4 million in favorable development from property other lines and $34.4 million in favorable marine and aviation development, partially offset by unfavorable property catastrophe development of $12.4 million . The release in long tail lines was due to favorable development of $44.3 million and $25.7 million in casualty and other, respectively. Net favorable prior year reserve development totaled $187.9 million for the year ended December 31, 2013 . The short-tailed lines benefited from $60.0 million in favorable property catastrophe development, $57.3 million in favorable property other lines releases and $19.6 million in favorable marine and aviation development. The release in long-tailed lines was due to $72.2 million in favorable casualty development partially offset by $21.3 million in unfavorable other lines development. The nature of the Company’s high excess of loss liability and catastrophe business can result in loss events that are both irregular and significant. Similarly, adjustments to reserves for individual years can be irregular and significant. Such adjustments are part of the normal course of business for the Company. There is no assurance that conditions and trends that have affected the development of liabilities in the past will continue. Accordingly, it may not be appropriate to extrapolate future redundancies or deficiencies based on the Company’s historical results. (b) Loss Reserve Discounting Except for certain workers’ compensation (including long term disability) liabilities and certain bodily injury liability claims, emanating from U.K. exposures, predominantly from the U.K. motor liability portfolio, the Company does not discount its unpaid losses and loss expenses. The Company utilizes tabular reserving for workers’ compensation (including long-term disability) unpaid losses that are considered fixed and determinable, and discounts such losses using interest rates of 3.75% in 2015 and 5% in 2014 . The reduction of the discount rate resulted from estimating the implied return of the market-based assets supporting the expected cash flows of our liabilities. The tabular reserving methodology results in applying uniform and consistent criteria for establishing expected future indemnity and medical payments (including an explicit factor for inflation) and the use of mortality tables to determine expected payment periods. Tabular unpaid losses and loss expenses, net of reinsurance, at December 31, 2015 and 2014 on an undiscounted basis were $747.4 million and $515.4 million , respectively. The related discounted unpaid losses and loss expenses were $445.3 million and $266.4 million at December 31, 2015 and 2014 , respectively. The significant increase in the reserves is due to the Catlin Acquisition, and the reserves assumed as a result of that transaction. See Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," for further information. The Company records a specific reserve allowance for Periodical Payment Orders ("PPO") related to bodily injury liability claims. This allowance includes the unpaid losses for claims already settled and notified as PPO at December 31, 2015 , as well as the unpaid losses for claims to be settled in the future. The future care element of the unpaid losses was discounted using interest rates of 2.0% and 1.5% at both December 31, 2015 and 2014 , respectively. Unpaid losses and loss expenses, net of reinsurance, at December 31, 2015 and 2014 on an undiscounted basis were $298.1 million and $249.8 million , respectively. After discounting the future care element, the unpaid losses and loss expenses were $167.9 million and $161.0 million at December 31, 2015 and 2014 , respectively. The increase in the reserves is due to the Catlin Acquisition, and the reserves assumed as a result of that transaction. See Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," for further information. The increase is partially offset by the increase in the discount rate used. The nature of the Company's high excess of loss liability and catastrophe business can result in loss events that are both irregular and significant. Similarly, adjustments to reserves for individual years can be irregular and significant. Such adjustments are part of the normal course of business for the Company. Conditions and trends that have affected development of liability in the past may not continue in the future. Accordingly, it is inappropriate to extrapolate future redundancies or deficiencies based upon historical experience. (c) Discontinued Asbestos and Run-Off Environmental Related Claims The Company’s reserving process includes a continuing evaluation of the potential impact on unpaid liabilities from exposure to discontinued asbestos and run-off environmental claims, including related loss adjustment expenses. Liabilities are established to cover both known and incurred but not reported claims. The Company’s reserving and exposures to environmental liability business currently written within the Casualty underwriting division are not included in this note, which only relates to specific discontinued and/or run-off coverages that were not originally written specifically to cover environmental hazards. The Company’s exposure to discontinued asbestos and run-off environmental claims arises from the following four sources: (1) Reinsurance contracts written, both on a proportional and excess basis, after 1972. The Company discontinued writing contracts with these exposures in 1985. Business written was across many different policies, each with a relatively small contract limit. The Company’s reported asbestos claims relate to both traditional products and premises and operations coverage. (2) Winterthur – business of Winterthur purchased by the Company from AXA Insurance (formerly Winterthur Swiss Insurance Company) in 2001. Pursuant to the Sale and Purchase Agreement and related agreements, AXA Insurance reimburses the Company for all asbestos losses. (3) During 2006, the Company acquired $40.2 million in losses through a loss portfolio transfer contract of which $18.3 million in losses related to asbestos and environmental claims. Given the terms of the policy, the combined aggregate limit on the total acquired reserves is limited to $60.0 million , not including coverage for claims handling costs over a defined period. (4) Catlin Acquisition - aviation insurance contracts written by Catlin in the Lloyd's market where the specific asbestos exclusion language was not implemented until 2003. Exposures only extend back to 1993 as Equitas was established to take on the Lloyd's market exposure for 1992 and prior. Exposure is due to asbestos-containing products in use by the aviation industry leading to claims against aviation manufacturers for asbestosis, mesothelioma and lung cancer. A reconciliation of the opening and closing unpaid losses and loss expenses related to discontinued asbestos and run-off environmental exposure claims for the years indicated is as follows: Year ended December 31, (U.S. dollars in thousands) 2015 2014 2013 Net unpaid losses and loss expenses at beginning of year $ 81,416 $ 80,435 $ 78,315 Net incurred losses and loss expenses 15,663 8,903 6,257 Less net paid losses and loss expenses 9,087 7,922 4,137 Net increase (decrease) in unpaid losses and loss expenses $ 6,576 $ 981 $ 2,120 Acquired reserves 5,712 — — Net unpaid losses and loss expenses at end of year 93,704 81,416 80,435 Unpaid losses and loss expenses recoverable at end of year 93,688 100,537 115,090 Gross unpaid losses and loss expenses at end of year $ 187,392 $ 181,953 $ 195,525 Reserves for incurred but not reported losses, net of reinsurance, included in the above table were $65.1 million , $49.3 million and $48.6 million at December 31, 2015, 2014 and 2013 , respectively. Unpaid losses recoverable are net of potential uncollectible amounts. At December 31, 2015 , the Company had 2,591 open claim files for potential discontinued asbestos claims exposures and 430 open claim files for potential run-off environmental claims exposures. Approximately 32% , 46% and 37% of the open claim files are due to precautionary claim notices in 2015 , 2014 and 2013 , respectively. Precautionary claim notices are submitted by the ceding companies in order to preserve their right to receive coverage under the reinsurance contract. The increase in total open claim files during 2015 was largely due to the Catlin Acquisition, as noted above. Such notices do not contain an incurred loss amount to the Company. The development of the number of open claim files for potential discontinued asbestos and run-off environmental claims, including precautionary claims, is as follows: Asbestos Claims Environmental Claims Total number of claims outstanding at December 31, 2012 1,073 354 New claims reported in 2013 178 34 Claims resolved in 2013 (154 ) (50 ) Total number of claims outstanding at December 31, 2013 1,097 338 New claims reported in 2014 456 190 Claims resolved in 2014 (154 ) (69 ) Total number of claims outstanding at December 31, 2014 1,399 459 New claims reported in 2015 272 67 Claims resolved in 2015 (246 ) (96 ) Acquired reserves 1,166 — Total number of claims outstanding at December 31, 2015 2,591 430 The Company’s reserving process includes a continuing evaluation of the potential impact on unpaid liabilities from exposure to discontinued asbestos and run-off environmental claims, including related loss adjustment expenses. Liabilities are established to cover both known and incurred but not reported claims. The estimation of loss and loss expense liabilities for discontinued asbestos and run-off environmental exposures is subject to much greater uncertainty than is normally associated with the establishment of liabilities for certain other exposures due to several factors, including: (i) uncertain legal interpretation and application of insurance and reinsurance coverage and liability; (ii) the lack of reliability of available historical claims data as an indicator of future claims development; (iii) an uncertain political climate which may impact, among other areas, the nature and amount of costs for remediating waste sites; and (iv) the potential of insurers and reinsurers to reach agreements in order to avoid further significant legal costs. Due to the potential significance of these uncertainties, the Company believes that no meaningful range of loss and loss expense liabilities beyond recorded reserves can be established. As the Company’s net unpaid loss and loss expense reserves related to discontinued asbestos and run-off environmental exposures are less than 1% of the total net reserves at December 31, 2015 and 2014 , further adverse development is not expected to be material to the Company’s overall net loss reserves. The Company believes it has made reasonable provision for its discontinued asbestos and run-off environmental exposures and is unaware of any specific issues that would significantly affect its estimate for loss and loss expenses.

Deposit Liabilities

Deposit Liabilities	12 Months Ended
	Dec. 31, 2015
Deposit Contracts, Liabilities [Abstract]
Deposit liabilities	Deposit Liabilities The Company has entered into certain insurance and reinsurance policies that transfer insufficient risk under GAAP to be accounted for as insurance or reinsurance transactions and are recognized as deposits. These structured P&C agreements have been recorded as deposit liabilities and are initially matched by an equivalent amount of investments. The Company has investment risk related to its ability to generate sufficient investment income to enable the total invested assets to cover the payment of the ultimate liability. See Note 6, "Investments ," for further information relating to the Company’s net investment income as well as realized and unrealized investment (losses) gains. Each deposit liability accrues at a rate equal to the internal rate of return of the payment receipts and obligations due during the life of the agreement. Where the timing and/or amount of future payments are uncertain, cash flows reflecting the Company’s actuarially determined best estimates are utilized. Deposit liabilities are initially recorded at an amount equal to the assets received. At December 31, 2015 and 2014 , total deposit liabilities were $1.2 billion . For the years ended December 31, 2015, 2014 and 2013 , interest expense of $42.2 million , $12.9 million and $48.0 million , respectively, was recorded related to the accretion of deposit liabilities. During the second quarter of 2014, the Company negotiated the termination of one of its larger structured indemnity contracts and as a result a net decrease of $28.7 million was recorded to interest expense. See Note 15, "Derivative Instruments ," for further information.

Future Policy Benefit Reserve

Future Policy Benefit Reserve	12 Months Ended
	Dec. 31, 2015
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Future policy benefit reserve	Future Policy Benefit Reserves Net future policy benefit reserves are comprised of the following: Year ended December 31 (U.S. dollars in thousands) 2015 2014 Traditional Life $ 792,001 $ 789,133 Annuities 3,371,499 3,918,066 Gross future policy benefit reserves $ 4,163,500 $ 4,707,199 Reinsurance recoverable - GreyCastle Life Retro Arrangements (3,719,131 ) (4,265,678 ) Reinsurance recoverable - U.S. Term Life Retro Arrangements (284,481 ) — Reinsurance recoverable - Other life retrocessions (13,801 ) (17,840 ) Net future policy benefit reserves $ 146,087 $ 423,681 The Company entered into long duration contracts that subject the Company to mortality and morbidity risks and that were accounted for as life premiums earned. Future policy benefit reserves were established using appropriate assumptions for investment yields, mortality, and expenses, including a provision for adverse deviation. At December 31, 2015 and 2014 , the average interest rate used for the determination of the future policy benefits for these contracts was 3.3% and 3.3% , respectively. Gross future policy benefit reserves for the years ended December 31, 2015 and 2014 were $4.2 billion and $4.7 billion , respectively. The decrease in gross future policy benefit reserves during 2015 was from normal course releases on single premium annuities in line with the benefits paid and mortality of underlying policyholders, as well as foreign exchange movements. Under the terms of the transaction described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ," the Company has reinsured $3.7 billion and $4.3 billion at December 31, 2015 and 2014 , respectively, of its future policy benefit reserves under the GreyCastle Life Retro Arrangements. The Company continues to own, on a funds withheld basis, assets supporting the GreyCastle Life Retro Arrangements consisting of cash, fixed maturity securities and accrued interest. Based upon the contractual right of offset, the funds withheld liability owing to GCLR is recorded net of future policy benefit reserves recoverable, and is included within "Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable)" on the consolidated balance sheets, and is comprised of the following at December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Assets held on a funds withheld basis relating to the GreyCastle Life Retro Arrangements $ 4,633,760 $ 5,420,694 Reinsurance recoverable from GCLR (3,719,131 ) (4,265,678 ) Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable) $ 914,629 $ 1,155,016 The Company has also reinsured an additional $284.5 million of its U.S. Term Life future policy benefit reserves ("U.S. Term Life Retro Arrangements") at December 31, 2015 . The Company continues to own, on a funds withheld basis, assets supporting the U.S. Term Life Retro Arrangements. Based upon the contractual right of offset, the funds withheld liability is recorded net of future policy benefit reserves recoverable, and is included within "Reinsurance balances payable" on the consolidated balance sheets.

Notes Payable and Debt and Fina

Notes Payable and Debt and Financing Arrangements	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Notes payable and debt and financing arrangements	Notes Payable and Debt and Financing Arrangements (a) Notes Payable and Debt The following table presents the Company's outstanding notes payable and debt as of December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Commitment/ In Use/ Commitment/ In Use/ Debt: 2.30% Senior Notes due 2018 $ 300,000 $ 298,015 $ 300,000 $ 297,344 5.75% Senior Notes due 2021 400,000 397,523 400,000 397,092 6.375% Senior Notes due 2024 350,000 349,029 350,000 348,920 4.45% Subordinated Notes due 2025 500,000 492,521 — — 6.25% Senior Notes due 2027 325,000 323,218 325,000 323,062 5.25% Senior Notes due 2043 300,000 296,294 300,000 296,162 5.5% Subordinated Notes due 2045 500,000 488,370 — — Total debt carrying value $ 2,675,000 $ 2,644,970 $ 1,675,000 $ 1,662,580 _______________ (1) Excluded from the table are certain credit facilities under which the Company is permitted to utilize up to $1.4 billion and $1.6 billion as of December 31, 2015 and December 31, 2014 , respectively, for revolving loans to support general operating and financing needs. However, as of December 31, 2015 and December 31, 2014 , $527.1 million and $606.1 million , respectively, were utilized under these facilities to issue letters of credit, leaving $822.9 million and $ 968.9 million , respectively, available to support other operating and financing needs. (2) "In Use/Outstanding" data represent December 31, 2015 and December 31, 2014 accreted values. All outstanding debt of the Company at December 31, 2015 and 2014 , which is identified in the table above, was issued by XL-Cayman, a 100% owned subsidiary of XL-Ireland and the only direct subsidiary thereof. XL-Ireland does not have significant assets or operations independent of XL-Cayman. XL-Cayman's outstanding debt is fully and unconditionally guaranteed by XL-Ireland. The ability of XL-Cayman, like that of the Company, to obtain funds from its subsidiaries to satisfy any of its obligations is subject to certain contractual restrictions, applicable laws and statutory requirements of the various countries in which the Company operates, including, among others, Bermuda, the United States, Ireland, Switzerland and the United Kingdom. For details of the required statutory capital and surplus for the principal operating subsidiaries of the Company, see Note 23, "Statutory Financial Data ." On September 15, 2014, the $600 million principal amount outstanding on the 5.25% Senior Notes issued by XL-Cayman was repaid at maturity. On March 30, 2015, XL-Cayman issued $500 million of subordinated notes due March 2025, with a fixed coupon of 4.45% , that are guaranteed by XL-Ireland. The notes are listed on the New York Stock Exchange. The notes were issued at 99.633% of the face amount and net proceeds were $492.2 million . Related expenses of the offering amounted to approximately $5.9 million . These costs were deferred and will be amortized over the term of the subordinated notes. On March 30, 2015, XL-Cayman issued $500 million of subordinated notes due March 2045, with a fixed coupon of 5.5% , that are guaranteed by XL-Ireland. The notes are listed on the New York Stock Exchange. The notes were issued at 99.115% of the face amount and net proceeds were $488.4 million . Related expenses of the offering amounted to approximately $7.2 million . These costs were deferred and will be amortized over the term of the subordinated notes. As a result of the Catlin Acquisition, the Company had assumed the following liabilities of Catlin, all of which were redeemed at par and extinguished in December of 2015: • Variable rate unsecured subordinated notes in the amounts of €7 million and $27 million due March 2035 and March 2036, respectively, issued by Catlin Underwriting (formerly Wellington Underwriting plc) in May 2006. The notes are subordinated to the claims of all senior creditors, as defined in the agreement governing the notes. The notes pay interest at a floating rate based on the rate on three-month deposits in U.S. dollars plus a margin of 295 basis points and 317 basis points, respectively. Interest is payable quarterly in arrears. The notes are redeemable at the discretion of the issuer. • Variable rate unsecured subordinated notes in the amounts of $31 million , $10 million and €11 million due September 2036, issued by Catlin Underwriting, in July 2006. The notes are subordinated to the claims of all senior creditors, as defined in the agreement governing the notes. The notes pay interest at a floating rate based on the rate on three-month deposits in U.S. dollars plus a margin of 310 basis points, 300 basis points and 300 basis points, respectively. Interest is payable quarterly in arrears. The notes are redeemable at the discretion of the issuer. The Company recognized a $5.6 million loss on early extinguishment of debt for the year ended December 31, 2015 . The Company was in compliance with all covenants at December 31, 2015 and 2014 , and the Company currently remains in compliance with all covenants. (b) Credit Facilities and Other Sources of Collateral The Company has several credit facilities provided on both syndicated and bilateral bases from commercial banks. As described in more detail below, the Company may utilize the full capacity of these credit facilities to issue letters of credit in support of non-admitted insurance and reinsurance operations in the U.S., and to meet capital requirements at Lloyd’s. Alternatively, under certain of the credit arrangements, the Company instead may elect to utilize a stated portion of such facilities' capacity for revolving loans to support other operating or financing needs, which would reduce the amount available for letters of credit. The Company’s available credit facilities at December 31 were as follows: (U.S. dollars in thousands) 2015 (1) 2014 (1) Total available credit facilities – commitments (2) $ 4,463,041 $ 3,575,000 Letters of credit – in use $ 2,515,653 $ 1,790,561 Collateralized by certain assets of the Company’s investment portfolio 50.9 % 66.2 % ____________ (1) As of December 31, 2015 and December 31, 2014 , there were fifteen and eight available credit facilities, respectively. (2) As of December 31, 2015 and December 31, 2014 the stated portion of allowable credit facilities permitted to be utilized for revolving loans was $1.4 billion and $1.6 billion , respectively. However, as of December 31, 2015 and December 31, 2014 , $527.1 million and $606.1 million , respectively, of such facilities' limits were utilized to issue letters of credit, leaving $822.9 million and $ 968.9 million , respectively, available either to issue additional letters of credit or to support other operating or financing needs under these particular facilities. In November 2015, we entered into four bilateral unsecured credit agreements, each providing for $125 million of letters of credit for Funds at Lloyd’s purposes (collectively the "FAL Facilities") for an aggregate amount of $500 million . Each of the FAL Facilities expires in 2019. The FAL Facilities replaced four unsecured bilateral facilities available for utilization by Catlin-Bermuda for Funds at Lloyd's purposes that we terminated in November 2015. On June 10, 2015, XL-Cayman entered into the fifth amendment to the credit agreement with Citicorp USA, Inc., as administrative agent and issuing lender, and the lenders party thereto (as amended, the "2015 Citi Facility"). The 2015 Citi Facility and a continuing agreement for standby letters of credit with Citibank, N.A. were initially entered into on May 7, 2013. On November 4, 2013, XL-Cayman entered into a credit agreement with Citicorp USA, Inc., as administrative agent and issuing lender, and the lenders party thereto and a continuing agreement for standby letters of credit with Citibank, N.A. (the "2013 Citi Facility" and, together with the 2015 Citi Facility, the "Citi Agreements"). Collectively, the Citi Agreements and the continuing agreements for standby letters of credit provide for issuance of letters of credit and revolving credit loans in an aggregate amount of up to $350 million . XL-Cayman has the option to increase the maximum amount of letters of credit and revolving credit loans available under the 2013 Citi Agreements with the lender's and issuing lender's consent. The commitments under the Citi Agreements expire on, and such credit facilities are available until, the earlier of (i) June 20, 2017 (with respect to the 2015 Citi Facility) and December 20, 2016 (with respect to the 2013 Citi Facility) and (ii) the date of termination in whole of the commitments upon an optional termination or reduction of the commitments by the account parties or upon the occurrence of certain events of default. On September 8, 2015, XL-Cayman entered into a new credit agreement with Goldman Sachs Mortgage Company, as administrative agent and issuing lender, and a continuing agreement for standby letters of credit with Goldman Sachs Bank USA. On September 9, 14, and 16, 2015, XL-Cayman entered into first, second and third amendments, respectively, to such credit agreement (as amended, the Goldman Facility"). XL-Cayman entered into the Goldman Facility to replace the letter of credit capacity under a credit agreement with Citicorp USA, Inc. initially entered into on August 6, 2013 that expired by its terms on September 20, 2015. The Goldman Facility and the continuing agreement for standby letters of credit provide for issuance of letters of credit in an aggregate amount of up to $200 million . XL-Cayman has the option to increase the maximum amount of letters of credit available under the Goldman Facility with the lender's and issuing lender's consent. The commitments under the Goldman Facility expire on, and such credit facility is available until, the earlier of (i) September 20, 2017 and (ii) the date of termination in whole of the commitments upon an optional termination or reduction of the commitments by the account parties or upon the occurrence of certain events of default. On December 30, 2014, XLIB reduced the capacity available under a continuous letter of credit facility between XL Insurance (Bermuda) Ltd. and Citibank Europe plc from $750 million to $600 million simultaneous with XL Insurance (Bermuda) Ltd. entering into a continuous $150 million letter of credit facility with ING Bank N.V., London Branch (the "ING Facility"). Both the Citi E.U. Facility and the ING Facility are collateralized by pledged financial assets. In November 2013, the Company (i) entered into two credit agreements (together, the "Syndicated Credit Agreements"), which provided for an aggregate amount of outstanding letters of credit and revolving credit loans of up to $2 billion , subject to certain options to increase the size of the facilities. The Syndicated Credit Agreements consist of (i) a secured credit agreement, which provides for the issuance of letters of credit and is collateralized by pledged financial assets, in an aggregate amount of up to $1 billion , and (ii) an unsecured credit agreement, which provides for the issuance of letters of credit and revolving credit loans in an aggregate amount of up to $1 billion . The Company has the option to increase the maximum amount of letters of credit available by an additional $500 million across the facilities under the Syndicated Credit Agreements. The commitments under the Syndicated Credit Agreements expire on, and such credit facilities are available until, the earlier of (i) November 22, 2018 and (ii) the date of termination in whole of the commitments upon an optional termination or reduction of the commitments by the account parties or upon the occurrence of certain events of default. The availability of letters of credit under the Syndicated Secured Facility is subject to a borrowing base requirement, determined on the basis of specified percentages of the face value of eligible categories of assets varying by type of collateral. In the event that such credit support is insufficient, the Company could be required to provide alternative security to cedants. This could take the form of insurance trusts supported by the investment portfolio or funds withheld (amounts retained by ceding companies to collateralize loss or premium reserves) using the Company's cash resources or combinations thereof. The face amount of letters of credit required is driven by, among other things, loss development of existing reserves, the payment pattern of such reserves, the expansion of business written by the Company and the loss experience of such business. We have $250 million of available capacity pursuant to a continuous credit agreement between XL Re and Citibank N.A. that is collateralized by pledged financial assets. As a result of the Catlin Acquisition the Company assumed, and may continue to access, the following letter of credit facilities: • A bilateral facility pursuant to a continuous credit agreement, available for utilization by Catlin-Bermuda, collateralized by pledged financial assets. As of December 31, 2015 , $230 million of capacity was available under this facility. • A bilateral facility pursuant to a continuous credit agreement, available for utilization by Catlin Re Switzerland Ltd, collateralized by pledged financial assets. As of December 31, 2015 , $175 million of capacity was available under this facility. • A facility managed by Lloyd's, acting for Catlin Syndicate 2003. As of December 31, 2015 , $8 million of letters of credit were issued under this facility. In addition to letters of credit, the Company has established insurance trusts in the U.S. that provide cedants with statutory relief required under state insurance regulation in the U.S. It is anticipated that the commercial facilities may be renewed on expiry but such renewals are subject to the availability of credit from banks utilized by the Company and may be renewed with materially different terms and conditions. In the event that such credit support is insufficient, the Company could be required to provide alternative security to cedants. This could take the form of additional insurance trusts supported by the Company’s investment portfolio or funds withheld using the Company’s cash resources. The value of letters of credit required is driven by, among other things, loss development of existing reserves, the payment pattern of such reserves, the expansion of business written by the Company and the loss experience of such business. In general, all of the Company’s bank facilities, indentures and other documents relating to the Company’s outstanding indebtedness (collectively, the "Company’s Debt Documents"), which are described above, contain cross acceleration or cross default provisions to each other and the Company’s Debt Documents contain affirmative covenants. These covenants provide for, among other things, minimum required ratings of the Company’s insurance and reinsurance operating subsidiaries and a maximum level of secured indebtedness that may be incurred in the future. In addition, the majority of the Company’s Debt Documents provide for an event of default in the event of a change of control of the Company, or some events involving bankruptcy, insolvency or reorganization of the Company. The Company’s credit facilities also contain minimum consolidated net worth covenants. Under the Syndicated Credit Agreements, in the event that XLIB, XL Re or XL Re Europe SE fails to maintain a financial strength rating of at least "A – " from A.M. Best, an event of default would occur. Given that all of the Company’s Debt Documents contain cross acceleration or cross default provisions, a default by one of these subsidiaries may result in all holders declaring their debt due and payable and accelerating all debt due under those documents. If this were to occur, the Company may not have funds sufficient at that time to repay any or all of such indebtedness.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	Derivative Instruments The Company enters into derivative instruments for both risk management and investment purposes. The Company is exposed to potential loss from various market risks, and manages its market risks based on guidelines established by management and the Risk and Finance Committee of the Company's Board of Directors. The Company recognizes all derivatives as either assets or liabilities on the balance sheets and measures those instruments at fair value, with the changes in fair value of derivatives shown in the consolidated statement of income as "Net realized and unrealized gains (losses) on derivative instruments" unless the derivatives are designated as hedging instruments. The accounting for derivatives that are designated as hedging instruments is described in Note 2(h), "Significant Accounting Policies - Derivative Instruments ." The following table summarizes information on the location and gross amounts of derivative fair values contained in the consolidated balance sheets at December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Asset Derivative Notional Amount Asset Derivative Fair Value (1) Liability Derivative Notional Amount Liability Derivative Fair Value (1) Asset Derivative Notional Amount Asset Derivative Fair Value (1) Liability Derivative Notional Amount Liability Derivative Fair Value (1) Derivatives designated as hedging instruments: Foreign exchange contracts $ 1,667,585 $ 64,289 $ 674,976 $ 11,941 $ 2,300,609 $ 121,862 $ 302,211 $ 2,936 Total derivatives designated as hedging instruments $ 1,667,585 $ 64,289 $ 674,976 $ 11,941 $ 2,300,609 $ 121,862 $ 302,211 $ 2,936 Derivatives not designated as hedging instruments: Investment Related Derivatives: Interest rate exposure $ — $ — $ — $ — $ 394,597 $ 206 $ 20,782 $ 51 Foreign exchange exposure 102,234 2,888 144,707 1,702 7,385 403 207,182 4,442 Credit exposure 8,433 652 71,614 12,067 2,408 165 14,270 9,836 Financial market exposure 37 77 26,500 417 46,145 360 33,670 34 Financial Operations Derivatives: Credit exposure — — — — — — — — Other Non-Investment Derivatives: Foreign exchange contracts 194,566 2,009 — — — — 81,194 282 Credit exposure 29,874 31 — — 31,060 60 — — Guaranteed minimum income benefit contract 46,032 19,368 46,032 19,368 46,249 13,603 46,249 13,603 Modified coinsurance funds withheld contract (2) 60,667 — 4,620,879 — 64,947 — 5,401,278 — Total derivatives not designated as hedging instruments $ 441,843 $ 25,025 $ 4,909,732 $ 33,554 $ 592,791 $ 14,797 $ 5,804,625 $ 28,248 ____________ (1) Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, in the balance sheets on a net basis where the Company has both a legal right of offset and the intention to settle the contracts on a net basis. (2) The fair value movements in derivative assets and liabilities relating to modified coinsurance funds withheld contracts are included within the associated asset or liability at each period end on the face of the balance sheets. Notional amounts associated with reinsurance agreements under which the Company assumes reinsurance risk are recorded as asset derivative notional amounts. Notional amounts associated with the GreyCastle Life Retro Arrangements under which the Company cedes reinsurance risk are recorded as liability derivative notional amounts. Included in the liability derivative notional amount at December 31, 2015 is the cumulative net realized and unrealized loss on life retrocession embedded derivative of $463.9 million . The following table summarizes information on the gross and net amounts of derivative fair values and associated collateral received related to derivative assets, or collateral provided relating to derivative liabilities reported in other assets and other liabilities within the consolidated balance sheets at December 31, 2015 and 2014 : Gross Amounts Not Offset in the Balance Sheets December 31, 2015 (U.S. dollars in thousands) Gross Amounts Recognized in the Balance Sheets Gross Amounts Offset in the Balance Sheets Net Amounts in the Balance Sheets Financial Instruments Cash Collateral Net Amounts Derivative Assets $ 89,314 $ 3,087 $ 86,227 $ — $ 30,958 $ 55,269 Derivative Liabilities $ 45,495 $ 3,087 $ 42,408 $ — $ — $ 42,408 December 31, 2014 (U.S. dollars in thousands) Derivative Assets $ 136,659 $ 696 $ 135,963 $ — $ 78,580 $ 57,383 Derivative Liabilities $ 31,184 $ 696 $ 30,488 $ — $ — $ 30,488 Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, on the balance sheets on a net basis where the Company has both a legal right of offset and the intention to settle the contracts on a net basis. The Company often enters into different types of derivative contracts with a single counterparty and these contracts are covered under netting agreements. At December 31, 2015 and 2014 , the Company held cash collateral related to foreign currency derivative positions and certain other derivative positions of $31.0 million and $78.6 million , respectively. The assets and liabilities related to the net collateral paid or held were recorded as Other assets and Other liabilities, respectively, within the consolidated balance sheets as the collateral and derivative positions are not intended to be settled on a net basis. (a) Derivative Instruments Designated as Fair Value Hedges The Company designates certain of its derivative instruments as fair value hedges or cash flow hedges and formally and contemporaneously documents all relationships between the hedging instruments and hedged items and links the hedging derivative to specific assets and liabilities. The Company assesses the effectiveness of the hedge both at inception and on an on-going basis, and determines whether the hedge is highly effective in offsetting changes in fair value or cash flows of the linked hedged item. The Company uses foreign exchange contracts to hedge the fair value of certain fixed income securities as well as to hedge certain net investments in foreign operations. In connection with the Catlin Acquisition and the FX Forwards, certain foreign exchange contracts utilized to hedge the fair value of certain net investments in foreign operations were de-designated as hedging instruments up until the time that the Catlin Acquisition was completed. Thereafter, these foreign exchange contracts were re-designated as hedging instruments. For the year ended December 31, 2015 , there is no exposure to fair value hedges. The following table provides the total impact on earnings relating to derivative instruments formally designated as fair value hedges along with the impacts of the related hedged items for the years indicated: Derivatives Designated as Fair Value Hedges (U.S. dollars in thousands) Hedged Items – Amount of Gain/(Loss) Recognized in Income Attributable to Risk Gain/(Loss) Recognized in Income on Derivative Deposit Liabilities Fixed Maturity Investments Ineffective Portion of Hedging Relationship – Gain/(Loss) Year Ended December 31, 2015 Interest rate exposure $ — Foreign exchange exposure — Total $ — $ — $ — $ — Year Ended December 31, 2014 Interest rate exposure $ — Foreign exchange exposure (15,663 ) Total $ (15,663 ) $ — $ 15,407 $ (256 ) Year Ended December 31, 2013 Interest rate exposure $ — Foreign exchange exposure (22,568 ) Total $ (22,568 ) $ — $ 23,065 $ 497 The gains (losses) recorded on both the derivative instruments and specific items designated as being hedged as part of the fair value hedging relationships outlined above along with any associated ineffectiveness in the relationships are recorded through Net realized and unrealized gains (losses) on derivative instruments in the income statement. Settlement of Fair Value Hedges A summary of the fair value hedges that have been settled and their impact on results during the indicated years ended December 31 as well as the remaining balance of fair value hedges and average years remaining to maturity are shown below: Settlement of Fair Value Hedges – Summary (U.S. dollars in thousands, except years) Fair Value Hedges – Notes Payable and Debt December 31, Fair Value Hedges – Deposit Liabilities December 31, 2015 2014 2015 2014 Cumulative reduction to interest expense $ — $ 21,624 $ 103,742 $ 95,333 Remaining balance $ — $ — $ 129,454 $ 137,862 Weighted average years remaining to maturity 0.0 0.0 21.6 23.2 During the second quarter of 2014, the Company negotiated the termination of one of its larger structured indemnity contracts. This contract had previously been designated as a fair value hedge that was settled. The remaining fair value adjustment of $47.0 million that was being amortized as a reduction of interest expense over the remaining term of the contract was recorded as an adjustment to interest expense at the termination date. As a result of the termination, a net decrease of $28.7 million was recorded to interest expense reflecting the realization of the remaining balance of the fair value hedge adjustment, partially offset by an accretion rate adjustment due to changes in cash flows. (b) Derivative Instruments Designated as Hedges of the Net Investment in a Foreign Operation The Company utilizes foreign exchange contracts to hedge the fair value of certain net investments in foreign operations. During the year ended December 31, 2015 and 2014 , the Company entered into foreign exchange contracts that were formally designated as hedges of investments in foreign subsidiaries, the majority of which have functional currencies of either U.K. sterling or the Euro. There was no ineffectiveness in these transactions. The following table provides the weighted average U.S. dollar equivalent of foreign denominated net assets that were hedged and the resulting derivative gain (loss) that was recorded in the foreign currency translation adjustment, net of tax, account within AOCI for the years ended December 31, 2015 and 2014 . Derivative Instruments Designated as Hedges of the Net Investment in a Foreign Operation – Summary (U.S. dollars in thousands) 2015 2014 Weighted average of U.S. dollar equivalent of foreign denominated net assets $ 1,769,106 $ 2,384,508 Derivative gains (losses) (1) $ 106,876 $ 120,643 ____________ (1) Derivative gains (losses) from derivative instruments designated as hedges of the net investment in a foreign operation are recorded in the cumulative translation adjustment account within AOCI for each period. (c) Derivative Instruments Not Formally Designated As Hedging Instruments The following table provides the total impact on earnings relating to derivative instruments not formally designated as hedging instruments under GAAP and from the ineffective portion of fair value hedges. The impacts are all recorded through Net realized and unrealized gains (losses) on derivatives in the income statement for the years ended December 31, 2015, 2014 and 2013 : Net Realized and Unrealized Gains (Losses) on Derivative Instruments (U.S. dollars in thousands) 2015 2014 2013 Investment Related Derivatives: Interest rate exposure $ (2,347 ) $ 15,959 $ 5,065 Foreign exchange exposure (1,542 ) 3,351 (948 ) Credit exposure (2,537 ) 400 (4,052 ) Financial market exposure (2,190 ) 411 6,302 Financial Operations Derivatives: Credit exposure — 5,023 (2,437 ) Other Non-Investment Derivatives: Foreign exchange exposure 60,319 — — Credit exposure 1,375 — — Guaranteed minimum income benefit contract — 2,257 10,457 Modified coinsurance funds withheld contract 45 2,741 (7,086 ) Total derivatives not designated as hedging instruments $ 53,123 $ 30,142 $ 7,301 Amount of gain (loss) recognized in income from ineffective portion of fair value hedges — (256 ) 497 Net realized and unrealized gains (losses) on derivative instruments $ 53,123 $ 29,886 $ 7,798 Net realized and unrealized gains (losses on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (151,691 ) $ (488,222 ) $ — The Company’s objectives in using these derivatives are explained below. (c)(i) Investment Related Derivatives The Company, either directly or through its investment managers, may use derivative instruments within its investment portfolio, including interest rate swaps, inflation swaps, commodity contracts, total return swaps, credit derivatives (single name and index credit default swaps), options, forward contracts and financial futures (foreign exchange, bond and stock index futures), primarily as a means of economically hedging exposures to interest rate, credit spread, equity price changes and foreign currency risk or, in limited instances, for efficient portfolio management. When using cleared (exchange traded) derivatives, the Company is exposed to the credit risk of the applicable clearing house and of the Company's future commissions merchant. When using uncleared (over-the-counter) derivatives, the Company is exposed to credit risk in the event of non-performance by the counterparties under any derivative contracts, although the Company generally seeks to use credit support arrangements with counterparties to help manage this risk. Investment Related Derivatives – Interest Rate Exposure The Company utilizes risk management and overlay strategies that incorporate the use of derivative financial instruments primarily to manage its fixed income portfolio duration and net economic exposure to interest rate risks. The Company may also use interest rate swaps to convert certain liabilities from a fixed rate to a variable rate of interest or use them to convert a variable rate of interest from one basis to another. Investment Related Derivatives – Foreign Exchange Exposure The Company has exposure to foreign currency exchange rate fluctuations through its operations and in its investment portfolio. The Company uses foreign exchange contracts to manage its exposure to the effects of fluctuating foreign currencies on the value of certain of its foreign currency fixed maturities. These contracts are not designated as specific hedges for financial reporting purposes and, therefore, realized and unrealized gains and losses on these contracts are recorded in income in the period in which they occur. These contracts generally have maturities of twelve months or less. In addition, certain of the Company's investment managers may, subject to investment guidelines, enter into forward contracts. Investment Related Derivatives – Credit Exposure Credit derivatives may be purchased within the Company's investment portfolio in the form of single name and basket credit default swaps and swaptions, which are used to mitigate credit exposure through a reduction in credit spread duration (i.e., macro credit strategies rather than single-name credit hedging) or exposure to securities of selected issuers, including issuers that are not held in the underlying fixed income portfolio. Investment Related Derivatives – Financial Market Exposure Stock index futures may be purchased within the Company's investment portfolio in order to create synthetic equity exposure and to add value to the portfolio with overlay strategies where market inefficiencies are believed to exist. From time to time, the Company may enter into other financial market exposure derivative contracts on various indices including, but not limited to, inflation and commodity contracts. (c)(ii) Financial Operations Derivatives – Credit Exposure During the fourth quarter of 2014, the remaining financial operations credit derivative exposure, which was written as part of the Company's previous financial lines business and is outside of the Company's investment portfolio, was terminated. The Company has no continuing financial operations derivative credit exposures. (c)(iii) Other Non-Investment Derivatives Foreign Exchange Contracts On January 9, 2015, the Company entered into the FX Forwards with Morgan Stanley Capital Services LLC and Goldman Sachs International. The purpose of the FX Forwards was to mitigate risk of foreign currency exposure related to the Catlin Acquisition. Following the closing of the Catlin Acquisition, the FX Forwards were settled. In connection with the Catlin Acquisition and the FX Forwards, during the first quarter of 2015 certain foreign exchange contracts utilized to hedge the fair value of certain net investments in foreign operations were de-designated as hedging instruments; subsequently during the second quarter, the hedging relationships were then re-established. In the fourth quarter of 2015, the Company entered into an average rate option to mitigate the risk of foreign currency exposure to certain GBP-denominated cash flows. The option will mature in the fourth quarter of 2016. Additionally, the Company has a small forward purchase to mitigate exposure to certain NZD-denominated cash flows. Credit Exposure During the year ended December 31, 2015 , the Company entered into a non-investment-related credit derivative relating to a number of reference pool mortgage tranches associated with actual mortgage loans that were securitized into agency mortgage-backed securities and sold as Structured Agency Credit Risk Notes. At December 31, 2015 , there was no reported event of default on this obligation. At December 31, 2015 , the notional outstanding related to the derivative was $29.9 million and the Company had recorded a derivative asset of $0.03 million . During the year ended December 31, 2015 , the Company recorded Net realized and unrealized gains of $0.1 million relating to this credit derivative. The credit derivative is recorded at fair value based upon models developed by the Company. Significant unobservable inputs considered in the valuation include the impact of changes in interest rates, future default, delinquency and prepayment rates, credit spreads, changes in credit quality, and other market factors. Guaranteed Minimum Income Benefit Contract The Company also has derivatives embedded in certain reinsurance contracts. For a certain life reinsurance contract, the Company pays the ceding company a fixed amount equal to the estimated present value of the excess of the guaranteed benefit over the account balance upon the policyholder's election to take the income benefit. The fair value of this derivative is determined based on the present value of expected cash flows. Modified Coinsurance and Funds Withheld Contracts The Company has modified coinsurance and funds withheld reinsurance agreements that provide for a return to be paid to the Company based on a portfolio of fixed income securities. As such, the agreements contain an embedded derivative. The embedded derivative is bifurcated from the funds withheld balance and recorded at fair value with changes in fair value recognized in earnings through Net realized and unrealized gains (losses) on derivative instruments. Modified Coinsurance Funds Withheld Reinsurance Agreements - Life Retrocession Embedded Derivative In addition, the Company has entered into the GreyCastle Life Retro Arrangements as described in Note 2(c), "Significant Accounting Policies - Total Investments - Investments Related to Life Retrocession Arrangements written on a Funds Withheld Basis," " Note 2(e), "Significant Accounting Policies - Reinsurance ," and Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ." The embedded derivative related to the GreyCastle Life Retro Arrangements is recorded at fair value with changes in fair value recognized in earnings through Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets. The change in the value of the life retrocession embedded derivative includes the interest income, realized and unrealized gains and losses on Life Funds Withheld Assets and certain related expenses subsequent to May 30, 2014 as follows: Components of Life Retrocession Embedded Derivative and Derivative Instruments - Life Funds Withheld Assets: (U.S. dollars in thousands) 2015 2014 Interest income - Life Funds Withheld Assets $ (193,568 ) $ (134,634 ) Realized and unrealized gains (losses) on Life Funds Withheld Assets 180,134 (318,065 ) Other 351 1,868 Net realized and unrealized gains (losses) on life retrocession embedded derivative $ (13,083 ) $ (450,831 ) Net adjustments related to future policy benefit reserves, net of tax $ (125,747 ) $ (21,786 ) Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets $ (12,861 ) $ (15,605 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (151,691 ) $ (488,222 ) (d) Contingent Credit Features Certain derivative agreements entered into by the Company or its subsidiaries contain credit rating downgrade provisions that permit early termination of the agreements by the counterparty if collateral is not posted following failure to maintain certain credit ratings from one or more of the principal credit rating agencies. If the Company were required to terminate such agreements early due to a credit rating downgrade, it could potentially be in a net liability position at the time of settlement of such agreements. The aggregate fair value of all derivative agreements containing such rating downgrade provisions that were in a liability position and any collateral posted under these agreements at December 31 for the years indicated were as follows: Contingent Credit Features - Summary: (U.S. dollars in thousands) 2015 2014 Aggregate fair value of derivative agreements with downgrade provisions in a net liability position $ 5,827 $ 5,770 Collateral posted to counterparty $ — $ —

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2015
Variable Interest Entities Disclosure [Abstract]
Variable interest entities	Variable Interest Entities At times, the Company has utilized VIEs both indirectly and directly in the ordinary course of the Company's business. In 2013, the Company, along with other investors, formed a new Bermuda-based company, New Ocean Capital Management Limited ("New Ocean"), to act as an investment manager that focuses on providing third-party investors access to insurance-linked securities and other insurance and reinsurance capital markets products. The Company holds a majority voting interest in New Ocean through its ownership of common shares and, accordingly, the financial statements of New Ocean have been included in the consolidated financial statements of the Company. None of the assets, liabilities, revenues or net income of New Ocean was material to the Company during the current year. The equity interest attributable to third party investors in New Ocean recorded in the Company’s Consolidated Balance Sheets as "Non-controlling interest in equity of consolidated subsidiaries" was $0.4 million and $0.2 million at December 31, 2015 and December 31, 2014 , respectively. Also in 2013, subsequent to the formation of New Ocean, the Company, along with other investors, formed a new Bermuda-based investment company, New Ocean Focus Cat Fund Ltd. ("New Ocean FCFL"), which is considered a VIE under GAAP. During the year ended December 31, 2015 , New Ocean FCFL invested in a special purpose reinsurer, Vector Reinsurance Ltd ("Vector Re"), formed for the purpose of underwriting collateralized excess of loss reinsurance with a focus on global property catastrophe risks. Most of Vector Re’s current underwriting activity relates to reinsurance business assumed from XL subsidiaries. Underwriting administration and claims services are provided to Vector Re by the Company, while investment advisory services are provided by New Ocean. The Company currently holds majority equity interests, which are considered to be the controlling financial interests, in New Ocean FCFL and New Ocean Market Value Cat Fund Ltd. ("New Ocean MVCFL"), and by extension, Vector Re. Accordingly, included in the consolidated financial statements of the Company are the total net assets of New Ocean FCFL, New Ocean MVCFL and Vector Re of $175.8 million and $139.9 million as of December 31, 2015 and December 31, 2014 , respectively. The Company’s shares of revenue and net income in these VIEs were not material to the Company for the twelve months ended December 31, 2015 . All inter-company transactions between the Company's entities have been eliminated in consolidation. The equity interest attributable to third party investors in New Ocean FCFL, New Ocean MVCFL and Vector Re recorded in the Company’s Consolidated Balance Sheets as "Non-controlling interest in equity of consolidated subsidiaries" was $70.5 million and $58.4 million as of December 31, 2015 and December 31, 2014 , respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies (a) Concentrations of Credit Risk The creditworthiness of any counterparty is evaluated by the Company, taking into account credit ratings assigned by rating agencies. The credit approval process involves an assessment of factors including, among others, the counterparty and country and industry credit exposure limits. Collateral may be required, at the discretion of the Company, on certain transactions based on the creditworthiness of the counterparty. The areas where significant concentrations of credit risk may exist include unpaid losses and loss expenses recoverable and reinsurance balances receivable (collectively, "reinsurance assets") and in the investment fixed income portfolio. Reinsurance Assets The Company’s reinsurance assets result from reinsurance arrangements in the course of its operations. A credit exposure exists with respect to reinsurance assets as they may be uncollectible. The Company manages its credit risk in its reinsurance relationships by transacting with reinsurers that it considers financially sound, and if necessary, the Company may hold collateral in the form of funds, trust accounts and/or irrevocable letters of credit. This collateral can be drawn on for amounts that remain unpaid beyond specified time periods on an individual reinsurer basis. For further details regarding the Company’s reinsurance assets, see Note 10, "Reinsurance ." Fixed Income Portfolio The Company did not have an aggregate direct investment in any single corporate issuer in excess of 5% of the Company's shareholders’ equity at December 31, 2015 and 2014 . Corporate issuers represent only direct exposure to fixed maturities and short-term investments of the parent issuer and its subsidiaries. These exposures exclude asset and mortgage backed securities that were issued, sponsored or serviced by the parent and government-guaranteed issues, but does include covered bonds. Broker credit risk In addition, the Company underwrites a significant amount of its insurance and reinsurance property and casualty business through brokers and a credit risk exists should any of these brokers be unable to fulfill their contractual obligations with respect to the payments of insurance and reinsurance balances to the Company. During the three years ended December 31, 2015, 2014 and 2013 , P&C gross written premiums generated from or placed by the below companies individually accounted for more than 10% of the Company’s consolidated gross written premiums from P&C operations, as follows: (Percentage of consolidated gross written premiums from P&C operations) 2015 2014 2013 AON Corporation and subsidiaries 18 % 18 % 21 % Marsh & McLennan Companies 19 % 20 % 23 % Willis Group and subsidiaries 13 % 11 % 13 % These brokers are large, well established companies and there are no indications that any of them are financially troubled. No other broker and no one insured or reinsured accounted for more than 10% of gross premiums written from P&C operations in any of the three years ended December 31, 2015, 2014 and 2013 . (b) Other Investments The Company has committed to invest in several limited partnerships and provide liquidity financing to a structured investment vehicle. At December 31, 2015 , the Company has commitments, which include potential additional add-on clauses, to invest an additional $127.6 million over a weighted average period of 6.0 years. (c) Investments in Affiliates The Company owns a minority interest in certain closed-end hedge funds, certain limited partnerships and similar investment vehicles, including funds managed by those companies. At December 31, 2015 , the Company has commitments, which include potential additional add-on clauses, to invest an additional $163.2 million over a weighted average period of 4.9 years. (d) Properties The Company rents space for certain of its offices under leases that expire through 2031. Total rent expense under operating leases for the years ended December 31, 2015, 2014 and 2013 was approximately $71.1 million , $36.6 million and $38.7 million , respectively. Future minimum rental commitments under existing operating leases are expected to be as follows: Year Ended December 31, (U.S. dollars in thousands) 2016 $ 69,256 2017 62,517 2018 56,122 2019 51,447 2020 46,356 2021-2031 131,826 Total minimum future rentals $ 417,524 During 2003, the Company entered into a purchase, sale and leaseback transaction to acquire new office space in London. The Company has recognized a capital lease asset of $73.4 million and $82.8 million , and deferred a gain of $22.3 million and $25.2 million related to this lease at December 31, 2015 and 2014 , respectively. The gain is being amortized to income in line with the amortization of the asset. The future minimum lease payments in the aggregate are expected to be $171.6 million and annually for the next five years are as follows: Year Ended December 31, (U.S. dollars in thousands) 2016 $ 11,870 2017 12,167 2018 12,471 2019 12,783 2020 13,103 2021-2028 109,248 Total minimum future lease payments $ 171,642 (e) Tax Matters XL-Ireland is an Irish corporation and, except as described below, neither it nor its non-U.S. subsidiaries have paid U.S. corporate income taxes on the basis that they are not engaged in a trade or business or otherwise subject to taxation in the United States. However, because definitive identification of activities that constitute being engaged in a trade or business in the United States is not provided by the Internal Revenue Code of 1986 ("IRS Code"), regulations or court decisions, there can be no assurance that the Internal Revenue Service will not contend that the Company or its non-U.S. subsidiaries are engaged in a trade or business or otherwise subject to taxation in the United States. If the Company or its non-U.S. subsidiaries were considered to be engaged in a trade or business in the United States (and, if the Company or such subsidiaries were to qualify for the benefits under the income tax treaty between the United States and Bermuda and other countries in which the Company operates, such businesses were considered to be attributable to a "permanent establishment" in the United States), the Company or such subsidiaries could be subject to U.S. tax at regular tax rates on their respective taxable income that is effectively connected with their U.S. trade or business plus an additional "branch profits" tax (at a rate as high as 30% ) on such income remaining after the regular tax, in which case there could be a significant adverse effect on the Company’s results of operations and financial condition. (f) Letters of Credit At December 31, 2015 and 2014 , $2.5 billion and $1.8 billion of letters of credit were outstanding, of which 50.9% and 66.2% , respectively, were collateralized by the Company’s investment portfolios, primarily supporting U.S. non-admitted business and the Company’s Lloyd’s syndicates’ capital requirements. (g) Litigation The Company and its subsidiaries are subject to litigation and arbitration in the normal course of business. These lawsuits and arbitrations principally involve claims on policies of insurance and contracts of reinsurance and are typical for the Company and for the property and casualty insurance and reinsurance industry in general. Such claims proceedings are considered in connection with the Company's loss and loss expense reserves. Reserves in varying amounts may or may not be established in respect of particular claims proceedings based on many factors, including the legal merits thereof. In addition to litigation relating to insurance and reinsurance claims, the Company and its subsidiaries are subject to lawsuits and regulatory actions in the normal course of business that do not arise from or directly relate to claims on insurance or reinsurance policies. This category of business litigation typically involves, among other things, allegations of underwriting errors or misconduct, employment claims, regulatory activity, shareholder disputes or disputes arising from business ventures. The status of these legal actions is actively monitored by management. Legal actions are subject to inherent uncertainties, and future events could change management's assessment of the probability or estimated amount of potential losses from pending or threatened legal actions. Based on available information, it is the opinion of management that the ultimate resolution of pending or threatened legal actions other than claims proceedings, both individually and in the aggregate, will not result in losses having a material adverse effect on the Company's financial position or liquidity at December 31, 2015 . If management believes that, based on available information, it is at least reasonably possible that a material loss (or additional material loss in excess of any accrual) will be incurred in connection with any legal actions other than claims proceedings, the Company discloses an estimate of the possible loss or range of loss, either individually or in the aggregate, as appropriate, if such an estimate can be made, or discloses that an estimate cannot be made. Based on the Company's assessment at December 31, 2015 , no such disclosures were considered necessary. (h) Financial Guarantee Exposures The Company's outstanding financial guarantee contracts as of December 31, 2015 provide credit support for a variety of collateral types with the exposures comprised of an aggregate amount of $80.8 million notional financial guarantee on two notes backed by zero coupon long dated bonds and bank perpetual securities, including some issued by European financial institutions. As of December 31, 2015 and December 31, 2014, the total gross claim liability recorded was nil and the contracts had a weighted average contractual term to maturity of 24.2 years and 25.2 years , respectively. Surveillance procedures to track and monitor credit deteriorations in the insured financial obligations are performed by the primary obligors for each transaction on the Company's behalf. Information regarding the performance status and updated exposure values is provided to the Company on a quarterly basis and evaluated by management in recording claims reserves. As of December 31, 2015 , there were no reported events of default on these obligations.

Share Capital

Share Capital	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Share capital	Share Capital (a) Authorized and Issued The authorized share capital of XL-Ireland is $9,999,900 and €40,000 , divided into: (i) 500,000,000 ordinary shares, par value $0.01 each, (ii) 499,990,000 undesignated shares, par value $0.01 , each and (iii) 40,000 subscriber shares, par value €1 each. Holders of ordinary shares are entitled to one vote for each share. In connection with the Catlin Acquisition described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," the Company issued 49.9 million ordinary shares to Catlin shareholders, which had an aggregate value as of the Acquisition Date of $1.85 billion . Ordinary Shares The following table is a summary of ordinary shares issued and outstanding: (in thousands) 2015 2014 Balance – beginning of year 255,183 278,253 Exercise of options 480 424 Net issuance of restricted shares 1,581 1,246 Share buybacks (1) (12,434 ) (24,740 ) Issue of shares 49,935 — Balance – end of year 294,745 255,183 ____________ (1) Includes share buybacks associated with authorized share buyback programs as well as purchases related to satisfying tax withholding obligations of employees in connection with the vesting of restricted shares granted under the Company’s equity compensation programs. Ordinary Share Buybacks On February 21, 2014, XL-Ireland announced that its Board of Directors approved an increase to the Share Buyback Program (the "February 2014 Program"), authorizing the purchase of up to $1.0 billion of ordinary shares, which included the amounts that remained under the previous Share Buyback Program. During the year ended December 31, 2015 , the Company purchased and canceled 4.5 million ordinary shares, respectively, under the February 2014 Program for $170.0 million . On August 6, 2015, XL-Ireland announced that its Board of Directors approved a new share buyback program, authorizing the purchase of up to $1.0 billion of ordinary shares (the "August 2015 Program"). This authorization also canceled approximately $97.6 million remaining under the February 2014 Program. During the year ended December 31, 2015 , the Company purchased and canceled 7.9 million ordinary shares under the August 2015 Program for $296.7 million . As of December 31, 2015 , $703.3 million remained available for purchase under the August 2015 Program. All share buybacks were carried out by way of redemption in accordance with Irish law and the Company's constitutional documents. All shares so redeemed were canceled upon redemption. (b) Non-controlling Interest in Equity of Consolidated Subsidiaries The Series D Preference Ordinary Shares and Series E Preference Ordinary Shares discussed in this section were issued by XL-Cayman and do not represent share capital of XL-Ireland. XL-Ireland has no preferred shares outstanding and has never issued any preferred shares. Series D Preference Ordinary Shares On October 15, 2011, XL-Cayman issued $350 million Series D Preference Ordinary Shares. Dividends on the Series D Preference Ordinary Shares are declared and paid quarterly at a floating rate of three-month LIBOR plus 3.120% on the liquidation preference. Series E Preference Ordinary Shares On March 15, 2007, XL-Cayman issued 1.0 million Fixed/Floating Series E Perpetual Non-Cumulative preference ordinary shares, par value $0.01 each, with liquidation preference value of $1,000 per share (the "Series E preference ordinary shares"). The Series E preference ordinary shares are perpetual securities with no fixed maturity date and are not convertible. Dividends on the Series E preference ordinary shares are declared and paid semi-annually at a rate of $32.50 per share. Acquisition of Non-controlling Preferred Shares In connection with the Catlin Acquisition described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," the Company acquired 0.6 million non-cumulative perpetual preferred shares issued by Catlin-Bermuda, par value of $0.01 per share, with liquidation preference of $1,000 per share, plus declared and unpaid dividends ("CICL Prefs"). Dividends at a rate of 7.249 percent on the liquidation preference are payable semi-annually on January 19 and July 19 in arrears as and when declared up to but not including January 2017. Thereafter, if the CICL-Prefs have not yet been redeemed, dividends will be payable quarterly at a rate equal to 2.975 percent plus the three-month LIBOR rate of the liquidation preference. The fair value of the outstanding CICL-Prefs on the date of the Catlin Acquisition was $562.3 million , which was based on the last trading price of such securities prior to the Catlin Acquisition. (c) Stock Plans The Company’s performance incentive programs provide for grants of stock options, restricted stock, restricted stock units, performance units and stock appreciation rights. Share-based compensation granted by the Company generally contains a vesting period of three or four years, and certain awards also contain performance conditions. The Company records compensation expense related to each award over its vesting period, incorporating the best estimate of the expected outcome of performance conditions where applicable. Compensation expense is generally recorded on a straight line basis over the vesting period of an award. In connection with, and effective upon, the completion of the Redomestication, XL-Ireland assumed the existing liabilities, obligations and duties of XL-Cayman under the NAC Re Corp. 1989 Stock Option Plan (the "1989 Plan"), the XL Group plc Amended and Restated 1991 Performance Incentive Program (the "1991 Program"), the XL Group plc Amended and Restated 1999 Performance Incentive Program for Employees (the "1999 Program"), the XL Group plc Directors Stock & Option Plan (the "Directors Plan"), the XL Group plc 2009 Cash Long-Term Incentive Program (the "2009 Program"), the XL Group plc Supplemental Deferred Compensation Plan (the "DC Plan," and together with the 1989 Plan, the 1991 Program, the 1999 Program, the Directors Plan and the 2009 Program, the "Programs"). Furthermore, in connection with, and effective upon, the completion of the Redomestication, the Programs were amended by XL-Cayman, among other things, to (i) provide that XL-Ireland and its Board of Directors will succeed to all powers, authorities and obligations of XL-Cayman and its Board of Directors under each Program, (ii) provide that the securities to be issued pursuant to each Program will consist of ordinary shares of XL-Ireland and (iii) otherwise to reflect the completion of the Redomestication. (d) Options The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: 2015 2014 2013 Dividend yield 2.00 % 2.00 % 2.00 % Risk free interest rate 1.70 % 1.81 % 1.14 % Volatility 21.6 % 34.0 % 37.0 % Expected lives 6.0 years 6.0 years 6.0 years The risk free interest rate is based on U.S. Treasury rates. The expected lives are estimated using the historical exercise behavior of grant recipients. The expected volatility is determined based upon a combination of the historical volatility of the Company’s stock and the implied volatility derived from publicly traded options. The following is a summary of the activity in the stock option plans for the indicated years ended December 31: (In thousands except for weighted average grant date fair value) 2015 2014 2013 Options granted to purchase ordinary shares under the Programs - in thousands 1,974 1,025 1,047 Weighted average grant date fair value $ 6.51 $ 8.60 $ 8.34 Total intrinsic value of stock options exercised $ 8,546 $ 7,499 $ 16,076 Options exercised during the year - in thousands 480 424 927 Compensation expense related to stock option plans $ 8,961 $ 9,961 $ 8,294 Estimated tax benefit (charge) related to stock option plans $ — $ (2 ) $ 50 The following is a summary of the stock options outstanding at December 31, 2015 , and related activity for the year then ended: Number of Shares ( in thousands ) Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) Outstanding – beginning of year 10,525 $ 32.42 4.8 years $ 86,690 Granted 1,974 36.43 Exercised (480 ) 20.79 Canceled/Expired (1,270 ) 75.34 Outstanding – end of year 10,749 $ 28.59 5.4 years $ 121,085 Options exercisable 7,741 $ 26.43 4.1 years $ 105,990 Available for grant (1) 6,907 ____________ (1) Available for grant includes shares that may be granted as either stock options, restricted stock, restricted stock units or performance units. The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (the difference between the Company’s closing stock price on the last trading day of the 2015 fiscal year and the exercise price, multiplied by the number of in-the-money-options) that would have been received by the option holders had all option holders exercised their options on December 31, 2015 . Total unrecognized stock-based compensation expense related to non-vested stock options was approximately $13.6 million at December 31, 2015 , which related to approximately 3.0 million options and is expected to be recognized over a weighted-average period of 1.4 years. The exercise price of the Company’s outstanding options granted is the market price of the Company’s ordinary shares on the grant date, except that during 2004, 295,000 options were granted with an exercise price of $88.00 when the market price was $77.10 . (e) Restricted Stock, Restricted Stock Units and Performance Units Restricted Stock Restricted stock awards issued under the 1991 Performance Incentive Program and the Directors Stock and Option Plan vest as set forth in the applicable award agreements. Each restricted stock award represents the Company’s obligation to deliver to the holder one ordinary share. The employees and directors who are granted a restricted stock award shall have all the rights of a shareholder, including the right to vote and receive dividends, but the shares are subject to certain restrictions prior to vesting relating to, among other things, forfeiture in the event of termination of employment and transferability. A summary of the restricted stock awards issued under the 1991 Performance Incentive Program and the Directors Stock and Option Plan for the indicated years ended December 31 is as follows: (In thousands except for weighted average grant date fair value) 2015 2014 2013 Restricted ordinary shares granted 44 46 181 Weighted average grant date fair value $ 37.11 $ 31.86 $ 29.44 Aggregate grant date fair value $ 1,613 $ 1,463 $ 5,325 Compensation expense related to restricted stock awards $ 3,889 $ 5,239 $ 4,419 Estimated tax benefit related to restricted stock awards $ 709 $ 1,233 $ 1,047 Total unrecognized stock based compensation expense related to non-vested restricted stock awards was approximately $0.3 million at December 31, 2015 , which is related to approximately 0.3 million restricted stock awards and is expected to be recognized over one year. Non-vested restricted stock awards at December 31, 2015 and for the year then ended were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 433 $ 36.41 Granted 44 $ 37.11 Vested (202 ) $ 29.08 Unvested at December 31, 2015 275 $ 41.90 Restricted Stock Units Each restricted stock unit represents the Company’s obligation to deliver to the holder one ordinary share upon satisfaction of the three -year vesting term. Restricted stock units are granted at the closing market price on the day of grant and entitle the holder to receive dividends declared and paid in the form of additional ordinary shares contingent upon vesting. A summary of the restricted stock units issued to officers of the Company and its subsidiaries for the indicated years ended December 31 is as follows: (In thousands) 2015 2014 2013 Restricted stock units granted 1,534 1,867 1,803 Aggregate grant date fair value $ 55,540 $ 57,134 $ 51,829 Compensation expense related to restricted stock units $ 48,937 $ 41,879 $ 32,874 Estimated tax benefit related to restricted stock units $ 13,271 $ 11,607 $ 8,813 Total unrecognized stock-based compensation expense related to non-vested restricted stock units was approximately $61.0 million at December 31, 2015 , which is related to approximately 3.1 million restricted stock units and is expected to be recognized over 1.3 years. Non-vested restricted stock units at December 31, 2015 and for the year then ended were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 3,248 $ 28.93 Granted 1,534 $ 36.20 Vested (1,536 ) $ 27.67 Forfeited (176 ) $ 32.45 Unvested at December 31, 2015 3,070 $ 32.99 Performance Units The performance units issued in 2015 vest after approximately three years, subject to the achievement of stated market metrics, and entitle the holder to shares of the Company’s ordinary shares. Each grant of performance units has a target number of shares, with final payouts ranging from 0% to 200% of the grant amount depending upon the achievement of stated market metrics along with each employee’s continued service through the vesting date. Performance units issue prior to 2015 have a similar vesting schedule and range of a target number of shares, but vesting and payout are dependent upon the achievement of stated relative and absolute financial performance metrics along with each employee's continued service through the vesting date. Furthermore, performance units granted in 2015 are granted at the closing market price on the day of grant and entitle the holder to receive dividends declared and paid in the form of additional ordinary shares contingent upon vesting. There are no dividend rights associated with the performance units. A summary of the performance units issued to certain employees of the Company for the indicated years ended December 31 is as follows: (In thousands) 2015 2014 2013 Performance units granted 781 572 656 Potential maximum share payout 1,563 1,144 1,312 Aggregate grant date fair value $ 28,082 $ 16,345 $ 17,753 Compensation expense related to performance units $ 12,942 $ 24,089 $ 1,041 Estimated tax benefit (charge) related to performance units $ 1,459 $ 4,250 $ (176 ) Total unrecognized stock-based compensation expense related to non-vested performance units was approximately $27.9 million at December 31, 2015 , which is related to approximately 1.9 million performance units and is expected to be recognized over 1.9 years. Non-vested restricted performance units as of December 31, 2015 were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 2,540 $ 25.24 Granted 781 $ 35.94 Vested (750 ) $ 19.35 Forfeited (63 ) $ 30.03 Performance driven addition (reduction) (627 ) $ 27.74 Unvested at December 31, 2015 1,881 $ 31.02 (f) Restricted Cash Units During the year ended December 31, 2015 , the Company granted approximately 2.6 million liability-classed stock units to certain employees with an aggregate grant date fair value of approximately $94.5 million . Each liability-classed restricted stock unit represents the Company's obligation to deliver to the holder a cash payment equivalent to the value of one ordinary share. The grants may vest either in three equal installments upon the first, second and third anniversaries of the date of grant; or in two equal installments upon the first and second anniversaries of the date of grant. Liability-classed stock units are granted at the closing market price on the day of grant and entitle the holder to receive dividends declared and are paid in cash contingent upon vesting. (g) Voting XL-Ireland’s Articles of Association restrict the voting power of any person to less than approximately 10% of the total voting power.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Retirement plans	Retirement Plans The Company provides pension benefits to eligible employees through various defined contribution and defined benefit retirement plans sponsored by the Company, which vary for each subsidiary. Plan assets are invested principally in equity securities and fixed maturities. (a) Defined contribution plans The Company has qualified defined contribution plans that are managed externally and to which employees and the Company contribute a certain percentage of the employee’s pensionable salary each month. The Company’s contribution generally vests over five years. The Company’s expenses for its qualified contributory defined contribution retirement plans were $87.5 million , $56.6 million and $49.4 million at December 31, 2015, 2014 and 2013 , respectively. (b) Defined benefit plans The Company maintains defined benefit plans that cover certain employees as follows: U.S. Plan A qualified non-contributory defined benefit pension plan exists to cover a number of U.S. employees. The plan was curtailed in 2002 and was closed to new entrants at that time. Under the terms of the curtailment, existing plan participants were no longer entitled to earn additional defined benefits for future services performed after the curtailment date; however, accrued benefits are eligible for annual cost-of-living increases. This plan also includes a non-qualified supplemental defined benefit plan designed to compensate individuals to the extent that their benefits under the Company’s qualified plan are curtailed due to IRS Code limitations. Benefits are based on years of service and compensation, as defined in the plan, during the highest consecutive three years of the employee’s last ten years of employment. In addition, pursuant to agreements entered into by the Company, certain former employees have received benefit type guarantees, not formally a part of any established plan. The liability recorded with respect to these agreements at each of December 31, 2015 and 2014 was $3.2 million representing the entire unfunded projected benefit obligations. U.K. Plans A contributory defined benefit pension plan exists in the U.K., but has been closed to new entrants since 1996. Benefits are based on length of service and compensation as defined in the trust deed and rules. In addition, during 2003, six individuals, four of whom are still employed by the Company in the U.K., transferred from a defined benefit plan into a defined contribution plan. These employees have a contractual agreement with the Company that provides a "no worse than final salary pension" guarantee in the event that they are employed by the Company until retirement, under which the Company guarantees to top-up their defined contribution pension to the level of pension that they would have been entitled to receive had they remained in the defined benefit scheme. The pension liability recorded with respect to these individuals was $4.8 million and $3.8 million at December 31, 2015 and 2014 , respectively, representing the entire unfunded projected obligation. In connection with the Catlin Acquisition described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," the Company assumed additional assets and liabilities associated with a further U.K. defined benefit plan within Catlin. This plan has been closed to new members since 1993. The current membership consists only of pensioners and deferred members. Benefits are based on length of service and compensation. Other European Plans Certain contributory defined benefit pension plans exist in several European countries, most notably Germany, which are closed to new entrants. Benefits are generally based on length of service and compensation defined in the related agreements. The Company acquired certain defined benefit pension liabilities with the acquisition of XL GAPS in 2007. The related balances are not included in the tables below as the liabilities are insured under an annuity type contract. The funded status by geographical region of all the Company’s retirement plans at December 31, 2015 and 2014 is as follows: Funded Status 2015 2014 U.S. $ (16,306 ) $ (13,124 ) U.K. (4,650 ) (7,742 ) Other European (21,807 ) (22,977 ) Funded status – end of year $ (42,763 ) $ (43,843 ) The status of all the Company’s retirement plans at December 31, 2015 and 2014 is as follows: Change in projected benefit obligation (U.S. dollars in thousands) 2015 2014 Projected benefit obligation – beginning of year $ 93,124 $ 81,976 Projected benefit obligation assumed due to Catlin Acquisition 28,414 — Service cost (1) 1,494 1,279 Interest cost 4,382 3,747 Actuarial (gain) / loss 2,821 13,402 Benefits and expenses paid (3,747 ) (2,761 ) Foreign currency (gains) / losses (4,047 ) (3,817 ) Settlements (276 ) (702 ) Projected benefit obligation – end of year $ 122,165 $ 93,124 (1) Service costs include cost of living adjustments on curtailed plans. Change in plan assets (U.S. dollars in thousands) 2015 2014 Fair value of plan assets – beginning of year $ 49,281 $ 47,158 Fair value of plan assets acquired due to Catlin Acquisition 33,131 — Actual return on plan assets (119 ) 3,543 Employer contributions 1,775 1,187 Benefits and expenses paid (3,305 ) (1,932 ) Foreign currency gains / (losses) (1,361 ) (675 ) Fair value of plan assets – end of year $ 79,402 $ 49,281 Funded status – end of year $ (42,763 ) $ (43,843 ) Accrued pension liability $ 42,763 $ 43,843 The components of the net benefit cost for the years ended December 31, 2015, 2014 and 2013 are as follows: Components of net benefit cost (U.S. dollars in thousands) 2015 2014 2013 Service cost $ 1,494 $ 1,279 $ 1,491 Interest cost 4,381 3,747 3,589 Expected return on plan assets (3,903 ) (2,859 ) (3,096 ) Amortization of net actuarial loss 1,617 812 1,440 Net benefit cost $ 3,589 $ 2,979 $ 3,424 Assumptions Several assumptions and statistical variables are used in the models to calculate the expenses and liability related to the plans. The Company, in consultation with its actuaries, determines assumptions about the discount rate, the expected rate of return on plan assets and the rate of compensation increase. The table below includes disclosure of these rates on a weighted-average basis, for the years ended December 31 as indicated: 2015 2014 U.S. Plans U.K. Plans Other European Plans U.S. Plans U.K. Plans Other European Plans Net Benefit Cost – Weighted-average assumptions Discount rate 3.91 % 3.70 % 2.42 % 4.95 % 4.60 % 3.50 % Expected long-term rate of return on plan assets 6.00 % 3.48 % N/A 6.50 % 4.60 % N/A Rate of compensation increase N/A 3.96 % 2.50 % N/A 5.50 % 2.50 % Benefit Obligation – Weighted-average assumptions Discount rate 4.25 % 3.70 % 2.42 % 3.91 % 4.60 % 2.40 % Rate of compensation increase N/A 3.96 % 2.50 % N/A 5.50 % 2.50 % The expected long-term rate of return assumption is determined by adding expected inflation to the expected long-term real rates of various asset classes taking into account expected volatility and correlation between the various asset classes. Plan Assets The U.S. Plan assets at December 31, 2015 consist of three new mutual funds. The first fund seeks long-term capital appreciation. The fund invests primarily in equity, Large Capital and Large Company Portfolio securities as well as Emerging Markets Assets. The second fund invests primarily in quality corporate and U.S. governmental bonds. The fund employs a high total investment return through a combination of current income and capital appreciation. The third fund seeks to outperform longer-duration benchmarks without excess volatility by investing primarily in longer duration, investment grade corporate and sovereign bonds. The U.S. Plan assets at December 31, 2014 consisted of two mutual funds. The first fund employed a core bond portfolio strategy that sought maximum total return and price appreciation consistent with the preservation of capital and prudent risk taking with the focus on intermediate – term high quality bonds. The second fund sought long term growth of capital, primarily in equity securities and depository receipts of U.S. and foreign issuers. The fair value of the U.S. Plan assets at December 31, 2015 and 2014 was $36.7 million and $38.1 million , respectively. As the investments of the retirement plan are mutual funds, they fall within Level 1 in the fair value hierarchy. The inputs and methodologies used in determining the fair value of these assets are consistent with those used to measure our assets as set out in Note 4, "Fair Value Measurements ." The U.K. pension plan assets, including those acquired as part of the Catlin Acquisition, are held in a separate trustee administered fund to meet long term liabilities to past and present employees. The table below shows the composition of the plans' assets and the fair value of each major category of plan assets at December 31, 2015 and 2014 , as well as the potential returns of the different asset classes. The totals of the asset values held in various externally managed portfolios are provided by third party pricing vendors. There is no significant concentration of risk within plan assets. The assets in the plans and the expected rates of return were as follows: (U.S. dollars in thousands, except percentages) Expected Return on Assets for 2015 Fair Value at December 31, 2015 Expected Return on Assets for2014 Fair Value at December 31,2014 Equities 6.2 % $ 7,893 7.4 % $ 7,787 Gilts 2.4 % 17,856 3.6 % 1,579 Corporate Bonds 3.4 % 16,915 4.6 % 1,594 Other (cash) 1.8 % 52 4.0 % 224 Total market fair value of assets $ 42,716 $ 11,184 Expected Cash Flows Under the U.S. defined benefit plans, the Company’s policy is to make annual contributions to the plan that are deductible for federal income tax purposes and that meet the minimum funding standards required by law. The contribution level is determined by utilizing the projected unit credit cost method and different actuarial assumptions than those used for pension expense purposes. The Company’s funding policy provides that contributions to the plan shall be at least equal to the minimum funding requirements of the Employee Retirement Income Security Act of 1974 ("ERISA"), as amended by the Pension Protection Act of 2006. During the fiscal year beginning January 1, 2016, the U.S. defined benefit plans expect to make contributions of $0.4 million . The estimated future benefit payments with respect to the U.S. defined benefit pension plans are as follows: (U.S. dollars in thousands) Retirement Plan Benefits Equalization Plan Total 2016 $ 988 $ 434 $ 1,422 2017 $ 1,023 $ 430 $ 1,453 2018 $ 1,054 $ 427 $ 1,481 2019 $ 1,240 $ 524 $ 1,764 2020 $ 1,396 $ 538 $ 1,934 2021-2025 $ 9,904 $ 3,032 $ 12,936 The U.K. plan is subject to triennial funding valuations, the most recent of which was conducted as of July 1, 2012 and was reported in 2013. The $2.4 million deficit (calculated on a realistic basis) is being funded over a 10 -year period. For the further U.K. plan assumed as part of the Catlin Acquisition the most recent funding valuation was prepared as at October 31, 2013. No contributions were required following that valuation. During 2016, it is expected that no contributions will be paid to the plan.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2015
Comprehensive Income Loss Note [Abstract]
Accumulated other comprehensive income (loss)	Accumulated Other Comprehensive Income (Loss) The changes in AOCI, net of tax, by component for the indicated years ended December 31 are as follows: (U.S. dollars in thousands) Unrealized Gains (Losses) on Investments (1) OTTI Losses Recognized in AOCI Foreign Currency Translation Adjustments Underfunded Pension Liability Cash Flow Hedge Total Balance, net of tax, December 31, 2012 $ 1,591,210 $ (121,371 ) $ 69,399 $ (20,892 ) $ 1,674 $ 1,520,020 OCI before reclassifications (742,768 ) — (62,934 ) 9,722 — (795,980 ) Amounts reclassified from AOCI (119,970 ) 32,193 206 1,440 439 (85,692 ) Tax benefit (expense) 93,960 (12 ) 7,870 (3,509 ) — 98,309 Net current period OCI - net of tax $ (768,778 ) $ 32,181 $ (54,858 ) $ 7,653 $ 439 $ (783,363 ) Balance, net of tax, December 31, 2013 $ 822,432 $ (89,190 ) $ 14,541 $ (13,239 ) $ 2,113 $ 736,657 OCI before reclassifications (1) 954,326 — (26,497 ) (10,877 ) — 916,952 Amounts reclassified from AOCI (143,330 ) 14,082 87 812 255 (128,094 ) Tax benefit (expense) (43,314 ) (939 ) 681 2,515 — (41,057 ) Net current period OCI - net of tax $ 767,682 $ 13,143 $ (25,729 ) $ (7,550 ) $ 255 $ 747,801 Balance, net of tax, December 31, 2014 $ 1,590,114 $ (76,047 ) $ (11,188 ) $ (20,789 ) $ 2,368 $ 1,484,458 OCI before reclassifications (1) (474,304 ) — (33,690 ) (6,100 ) — (514,094 ) Amounts reclassified from AOCI (346,911 ) 18,987 — 1,145 (200 ) (326,979 ) Tax benefit (expense) 34,195 (442 ) 8,375 1,103 — 43,231 Net current period OCI - net of tax $ (787,020 ) $ 18,545 $ (25,315 ) $ (3,852 ) $ (200 ) $ (797,842 ) Balance, net of tax, December 31, 2015 $ 803,094 $ (57,502 ) $ (36,503 ) $ (24,641 ) $ 2,168 $ 686,616 ____________ (1) Included in these amounts is the impact of Shadow Adjustments. As of December 31, 2014, $445.1 million was recorded. During the year ended December 31, 2015 , additional net impacts of $(170.7) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $274.4 million at December 31, 2015 . The reclassifications out of AOCI along with the associated income statement line items affected by component, and the total related tax (expense) benefit for indicated years ended December 31, are as follows: Gross Amount Reclassified From AOCI Details About AOCI Components (U.S. dollars in thousands) 2015 2014 Affected Line Item in the Statement of Income Unrealized gains and losses on investments: $ (316,508 ) $ (175,639 ) Net realized gains (losses) on investments sold 95,344 $ 54,095 OTTI on investments (125,747 ) $ (21,786 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (346,911 ) $ (143,330 ) Total before tax 7,597 $ (1,593 ) Provision (benefit) for income tax $ (339,314 ) $ (144,923 ) Net of tax OTTI losses recognized in OCI: $ 18,014 $ 11,848 Net realized gains (losses) on investments sold 973 $ 2,234 OTTI on investments transferred to (from) OCI $ 18,987 $ 14,082 Total before tax (32 ) $ (175 ) Provision (benefit) for income tax $ 18,955 $ 13,907 Net of tax Foreign Currency Translation: Foreign exchange relating to affiliate investments $ — $ 87 Exchange gains (losses) - before tax — $ — Provision (benefit) for income tax $ — $ 87 Net of tax Underfunded Pension Liability: Pension expense $ 1,145 $ 812 Operating Expenses (401 ) $ (206 ) Provision (benefit) for income tax $ 744 $ 606 Net of tax Gains and losses on cash flow hedges: Interest rate contracts $ (200 ) $ 255 Interest Expense — $ — Provision (benefit) for income tax $ (200 ) $ 255 Net of tax Total reclassifications for the period, gross of tax $ (326,979 ) (128,094 ) Tax (benefit) expense 7,164 (1,974 ) Total reclassifications for the period, net of tax $ (319,815 ) (130,068 )

Dividends

Dividends	12 Months Ended
	Dec. 31, 2015
Dividends Disclosure [Abstract]
Dividends	Dividends In 2015, two quarterly dividends of $0.16 were paid to ordinary shareholders of record at March 13 and June 15 and two quarterly dividends of $0.20 per share were paid to all ordinary shareholders of record at September 15 and December 15. In 2014, four quarterly dividends of $0.16 per share were paid to all ordinary shareholders of record at March 14, June 13, September 15 and December 15. In 2013, four quarterly dividends of $0.14 per share were paid to all ordinary shareholders of record at March 15, June 14, September 13 and December 13. The Company paid preference shareholders for the indicated years ended December 31, as follows: (U.S. dollars in millions) 2015 2014 2013 Series D preference ordinary shares (1) (2) $ 11.8 $ 11.7 $ 12.3 Series E preference ordinary shares (3) $ 65.1 $ 65.1 $ 65.1 Non-cumulative perpetual preferred shares (4) $ 21.8 $ — $ — ____________ (1) On October 30, 2015 , the Company announced that the Board of Directors of XL-Cayman resolved to pay a dividend of $8.7787 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend was paid on January 15, 2016 to all shareholders of record at January 1, 2016 . (2) On February 19, 2016 , the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $9.349 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016 . (3) On February 19, 2016 , the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $32.50 per share on XL-Cayman’s Series E Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016 . (4) On January 12, 2016 , the Board of Directors of Catlin-Bermuda resolved to pay a dividend in the aggregate amount of $21.8 million on CICL Prefs. The dividend was paid on January 19, 2016 to all shareholders of record at December 31, 2015 .

Taxation

Taxation	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Taxation	Taxation The Company's Irish operations, including the parent company XL-Ireland, are subject to income and capital gains tax in Ireland under applicable Irish law. The Company’s Bermuda subsidiaries are not subject to any income, withholding or capital gains taxes under current Bermuda law. In the event that there is a change such that these taxes are imposed, the Bermuda subsidiaries would be exempted from any such tax until March 2035 pursuant to the Bermuda Exempted Undertakings Tax Protection Act 1966, and the Exempted Undertakings Tax Protection Amendment Act 2011. The Company’s U.S. subsidiaries are subject to federal, state and local corporate income taxes and other taxes applicable to U.S. corporations. The provision for federal income taxes has been determined under the principles of the consolidated tax provisions of the IRS Code and Regulations thereunder. The Company has operations in subsidiary and branch form in various other jurisdictions around the world, including but not limited to the U.K., Switzerland, Ireland, Germany, France, Canada, Brazil and various other countries in Latin America and Asia that are subject to relevant taxes in those jurisdictions. Deferred income taxes have not been accrued with respect to certain undistributed earnings of subsidiaries located outside of Ireland. If the earnings were to be distributed, as dividends or otherwise, such amounts may be subject to withholding taxation in the jurisdiction of the paying entity. The Company does not assert that all earnings arising in the U.S. will be permanently reinvested in that jurisdiction and, accordingly, a provision for withholding taxes arising in respect of current period U.S. earnings has been made. No withholding taxes are accrued with respect to the earnings of the Company’s subsidiaries arising outside the U.S., as it is the intention that all such earnings, which would be subject to withholding tax, will remain reinvested indefinitely. The Company’s current corporate structure is such that distribution of earnings from subsidiaries located outside of the U.S. would not be subject to significant incremental taxation. It is not practicable to estimate the amount of additional withholding taxes that might be payable on such earnings due to a variety of factors, including the timing, extent and nature of any repatriation. The following table details the years that are the subject of open examinations, by major tax jurisdiction. While the Company cannot estimate with certainty the outcome of these examinations, the Company does not believe that adjustments from open tax years will result in a significant change to the Company's results from operations. Jurisdiction Tax Years U.S. 2013 Ireland 2006 - 2009 Germany 2010 - 2013 France 2013 - 2014 The following table details open tax years that are open to assessment by local tax authorities, in the following major tax jurisdictions. Jurisdiction Tax Years U.S. 2012 - 2015 Ireland 2006 - 2015 U.K. 2013 - 2015 Germany 2010 - 2015 Switzerland 2011 - 2015 France 2013 - 2015 The Company’s income (loss) before income tax and non-controlling interests was distributed between U.S. and non-U.S. for the years ended December 31, 2015, 2014 and 2013 as follows: Income (loss) before income tax: (U.S. dollars in thousands) 2015 2014 2013 U.S. $ (5,931 ) $ 228,708 $ 188,503 Non U.S. 1,300,109 137,027 1,025,649 Total $ 1,294,178 $ 365,735 $ 1,214,152 The income tax provisions for the years ended December 31, 2015, 2014 and 2013 were as follows: (U.S. dollars in thousands) 2015 2014 2013 Current expense (benefit): U.S. $ (22,698 ) $ 45,598 $ 49,566 Non U.S. 67,784 81,371 41,921 Total current expense (benefit) $ 45,086 $ 126,969 $ 91,487 Deferred expense (benefit): U.S. $ (63,491 ) $ 8,572 $ 700 Non U.S. (756 ) (38,644 ) (14,682 ) Total deferred expense (benefit) $ (64,247 ) $ (30,072 ) $ (13,982 ) Total tax expense (benefit) $ (19,161 ) $ 96,897 $ 77,505 The applicable statutory tax rates of the most significant jurisdictions contributing to the overall taxation of the Company are: Jurisdiction Applicable Statutory Taxation Rates Ireland (1) 12.50 % Ireland (1) 25.00 % Bermuda — % U.S. 35.00 % U.K. 20.25 % Switzerland (2) 7.83 % Switzerland (2) 21.20 % Germany 15.00 % France 38.00 % ____________ (1) The different applicable statutory taxation rates in Ireland relate to entities classified as trading or non-trading companies. (2) The different applicable statutory taxation rates in Switzerland relate to entities classified as trading or holding companies. The weighted average expected tax provision has been calculated using the pre-tax accounting income (loss) in each jurisdiction multiplied by that jurisdiction’s applicable statutory tax rate. A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate for the years ended December 31, 2015, 2014 and 2013 is provided below: (U.S. dollars in thousands) 2015 2014 2013 Expected tax (benefit) provision at weighted average rate $ (50,797 ) $ 132,775 $ 43,092 Permanent differences: Non-taxable (income) loss (23,036 ) (19,870 ) (50,745 ) Revision to prior year estimates 7,402 2,016 8,551 State, local and foreign taxes 27,499 47,078 12,225 Valuation allowance 9,517 (181 ) 5,754 Net allocated investment income (405 ) 3,399 5,949 Stock options (433 ) 411 1,501 Non-deductible expenses 42,839 22,556 23,662 Other investment related adjustments 2,075 (2,916 ) — Adjustments related to GreyCastle Life Retro Arrangements (35,045 ) (99,535 ) — Change in tax rates (11,877 ) 3,974 (2,484 ) Uncertain tax positions 13,100 7,190 30,000 Total tax expense (benefit) $ (19,161 ) $ 96,897 $ 77,505 Significant components of the Company’s deferred tax assets and liabilities at December 31, 2015 and 2014 were as follows: (U.S. dollars in thousands) 2015 2014 Deferred tax asset: Net unpaid loss reserve discount $ 111,584 $ 90,262 Net unearned premiums 80,434 72,752 Compensation liabilities 94,013 77,578 Net operating losses 181,295 49,834 Investment adjustments 14,399 13,022 Pension 10,370 8,114 Bad debt reserve 7,425 6,626 Amortizable goodwill 5,396 6,694 Net unrealized depreciation on investments 5,051 1,484 Stock options 16,192 11,985 Depreciation 13,299 7,599 Net realized capital losses 98,756 97,189 Deferred intercompany capital losses 26,164 57,427 Untaxed Lloyd's result 3,769 7,254 Deferred acquisition costs 31,133 11,386 Currency translation adjustments 6,280 — Other 24,977 2,282 Deferred tax asset, gross of valuation allowance $ 730,537 $ 521,488 Valuation allowance 276,301 207,062 Deferred tax asset, net of valuation allowance $ 454,236 $ 314,426 (U.S. dollars in thousands) 2015 2014 Deferred tax liability: Net unrealized appreciation on investments $ 51,010 $ 63,642 Unremitted earnings $ 3,739 $ 5,125 Deferred acquisition costs 8,308 2,737 Currency translation adjustments 1,210 3,969 Regulatory reserves 64,352 65,965 Investment adjustment 6,373 12,061 Untaxed Lloyd’s result — 11,422 Depreciation 11,500 — Syndicate capacity 92,756 — Intangible asset 40,126 — Other 13,202 11,260 Deferred tax liability $ 292,576 $ 176,181 Net Deferred Tax Asset $ 161,660 $ 138,245 The deferred tax asset and liability balances presented above represent the gross deferred tax asset and liability balances across each tax jurisdiction. The deferred tax asset balances of $282.3 million and $204.5 million at December 31, 2015 and 2014 , respectively, and deferred tax liability balances of $120.7 million and $66.2 million at December 31, 2015 and 2014 , respectively, disclosed on the consolidated balance sheets include netting of certain deferred tax assets and liabilities within a tax jurisdiction to the extent such netting is consistent with the regulations of the tax authorities in those jurisdictions. At December 31, 2015 and 2014 , the valuation allowance of $276.3 million and $207.1 million , respectively, related primarily to net operating loss and realized capital loss carryforwards in the following jurisdictions: Jurisdiction (U.S. dollars in thousands) 2015 2014 Switzerland $ 7,818 $ 1,459 Ireland 93,396 72,363 U.S. 106,624 123,695 U.K. 46,732 1,632 Other 21,731 7,913 Valuation Allowance Total $ 276,301 $ 207,062 The increase in the valuation allowance in 2015 of $69.2 million was primarily due to the inclusion of valuation allowances on the acquired business, the establishment of a valuation allowance on a U.K. subsidiary, and the increase of the existing valuation allowances as a result of the current year losses in the U.K. and Ireland primarily due to acquisition related expenses, partially offset by a reduction of a portion of the valuation allowance held against capital loss carry-forwards in the U.S, that expired in 2015. At December 31, 2015 , the Company had U.S. net operating loss carryforwards of $108.0 million ( $37.8 million tax effected) which were primarily generated during 2015. Of this amount, approximately $48.3 million are subject to restrictions on timing and utilization under §382 of the IRS Code. Management has reviewed historical taxable income and future taxable income projections for its U.S. group and has determined that in its judgment, all of the U.S. net operating losses will more likely than not be realized as reductions to future taxable income prior to expiration through 2034. At December 31, 2015, the Company had U.S. realized capital loss carryforwards of approximately $190.8 million ( $66.8 million tax effected). The five year limitation for the utilization of realized capital losses applies to this balance. Losses of $33.8 million will expire at the end of 2016 with another $157.0 million of realized capital losses expiring in future years through 2020. A valuation allowance of $66.8 million has been established in respect of all of these realized capital losses. At December 31, 2015 , the Company also had $74.8 million of U.S. capital losses arising from a prior year sale of investments to an international affiliate ( $26.2 million tax effected), against which a valuation allowance of $26.2 million has been established. These losses cannot be utilized to offset any future U.S. realized capital gains, and will not begin to expire, until the underlying assets have been sold to unrelated parties. At December 31, 2015 , net operating loss carryforwards in the U.K. were approximately $290.0 million ( $58.0 million tax effected) and have no expiration. At December 31, 2015 , the Company also had $7.2 million of U.K. capital losses ( $1.4 million tax effected), with a valuation allowance of $46.0 million on these combined losses after consideration of deferred tax liabilities. Management has reviewed historical taxable income for the U.K. subsidiaries with carryforward losses and has determined that in its judgment, insufficient historical positive evidence exists that the U.K. loss carryforwards will be realized as reductions to future taxable income within a reasonable period, and therefore has established a valuation allowance on these loss carryforwards. Management will continue to evaluate income generated in future periods by these U.K. subsidiaries in determining the reasonableness of its position. At December 31, 2015 , net operating loss carryforwards in Switzerland were approximately $118.9 million ( $9.2 million tax effected). Losses of $1.8 million and $47.0 million will expire in 2018 and 2019, respectively, with the remaining $70.1 million expiring through 2022. A valuation allowance of $7.7 million has been established in respect of the Swiss net operating losses after considering deferred tax liability offsets. At December 31, 2015 , net operating loss carryforwards in Ireland were approximately $460.0 million ( $57.5 million tax effected), with a further $122.1 million ( $30.5 million tax effected) of capital losses carried forward. Although these Irish losses may be carried forward indefinitely, a valuation allowance of $88.0 million has been established in respect of all of these Irish losses due to the uncertainty surrounding any future loss utilization. Management believes it is more likely than not that the tax benefit of the remaining net deferred tax assets will be realized. Shareholders’ equity at December 31, 2015 and 2014 reflected tax benefits of $9.2 million and $4.0 million , respectively, related to the excess of tax deductions over book compensation expense for stock awards exercised/vested by the Company's U.S. subsidiaries. At December 31, 2015 and 2014 , the Company had unrecognized tax benefits of $80.6 million and $37.2 million , respectively. If recognized, the full amount of these unrecognized tax benefits would decrease the annual effective tax rate. The Company does not currently anticipate any significant change in unrealized tax benefits during 2016. The following table presents a reconciliation of the Company’s unrecognized tax benefits: (U.S. dollars in thousands) 2015 2014 2013 Unrecognized tax benefits, beginning of the year $ 37,190 $ 30,000 $ — Increases for tax positions taken during the year 20,370 12,182 9,591 Increases for tax positions taken in prior years (1) 38,650 15,304 20,409 Decreases for tax positions taken in prior years (4,850 ) (20,296 ) — Decreases for lapse of the applicable statute of limitations (10,770 ) — — Unrecognized tax benefits, end of year $ 80,590 $ 37,190 $ 30,000 ____________ (1) Included in this amount is approximately $30.3 million of unrecognized tax benefits related to the Catlin Acquisition that existed as of the Acquisition Date. Of this amount, $4.8 million had been specifically identified as an unrecognized tax benefit, and the remaining $25.5 million was included in deferred tax liability. In conjunction with the Catlin Acquisition, management determined that this amount should be reclassified as an unrecognized tax benefit. The Company’s policy is to recognize any interest and penalties related to unrecognized tax benefits as a component of tax expense. At December 31, 2015 and 2014 , the Company had accrued interest and penalties of $0.4 million .

Statutory Financial Data

Statutory Financial Data	12 Months Ended
	Dec. 31, 2015
Statutory Capital And Surplus Disclosure Text Block [Abstract]
Statutory financial data	Statutory Financial Data The Company’s ability to pay dividends or return capital from shareholders’ equity is limited by applicable laws and regulations of the various jurisdictions in which the Company’s principal operating subsidiaries operate, certain additional required regulatory approvals and financial covenants contained in the Company’s credit facilities. The payment of dividends to XL-Ireland and XL-Cayman, the Company’s holding companies, and by the Company’s principal operating subsidiaries is regulated under the laws of various jurisdictions including Bermuda, the U.K., Ireland and Switzerland and certain insurance statutes of various U.S. states in which the principal operating subsidiaries are licensed to transact business and the other jurisdictions where the Company has regulated subsidiaries. In addition, XL-Ireland, our ultimate holding company, is domiciled in Ireland. Following the implementation of Solvency II on January 1, 2016, Solvency II applies at different levels of operations with different requirements. The group is regulated by Solvency II at the level of the group and our European subsidiaries are regulated by Solvency II at the subsidiary level. The Central Bank of Ireland ("CBI") is our group supervisor working in conjunction with the group's college of regulatory supervisors. Statutory capital and surplus for the principal operating subsidiaries of the Company for the years ended December 31, 2015 and 2014 are summarized below: (U.S. dollars in thousands) Bermuda (1) U.S. (2) U.K., Europe and Other 2015 2014 2015 2014 2015 2014 Required statutory capital and surplus $ 7,722,123 $ 6,194,832 $ 747,313 $ 668,794 $ 4,445,247 $ 1,604,721 Actual statutory capital and surplus (3) $ 11,112,176 $ 10,309,895 $ 2,234,767 $ 2,233,596 $ 6,054,122 $ 2,712,552 ____________ (1) Required statutory capital and surplus at December 31, 2015 represents 100% Bermuda Solvency Capital Requirement ("BSCR") level for the top Bermuda operating subsidiary, XL Insurance (Bermuda) Ltd, calculated on a consolidated basis (and therefore includes a BSCR requirement for all regions). (2) Required statutory capital and surplus represents 100% Risk-Based Capital level for principal U.S. operating subsidiaries. (3) Statutory assets in Bermuda include investments in other U.S. and international subsidiaries reported separately herein. Statutory net income (loss) for the principal operating subsidiaries of the Company for the years ended December 31, 2015, 2014 and 2013 is summarized below: (U.S. dollars in thousands) 2015 2014 2013 Bermuda $ 1,513,924 $ 361,022 $ 1,241,878 U.S. $ 17,574 $ 155,751 $ 124,310 U.K., Europe and Other $ (125,758 ) $ 215,787 $ 1,465 The difference between statutory financial statements and statements prepared in accordance with GAAP varies by jurisdiction, however, the primary difference is that statutory financial statements do not reflect deferred policy acquisition costs, deferred income tax net assets, intangible assets, or unrealized appreciation on investments, but they do reflect any unauthorized/authorized reinsurance charges. Certain restrictions on the payment of dividends from retained earnings by the Company’s principal operating subsidiaries are further detailed below. Management has evaluated the group and principal operating subsidiaries’ ability to maintain adequate levels of statutory capital, liquidity and rating agency capital and believes they will be able to do so. In performing this analysis, management has considered the most recent statutory capital position of each of the principal operating subsidiaries as well as the group overall, through its holding companies as a result of Solvency II group regulation effective in 2016. In addition, management has evaluated the ability of the holding companies to allocate capital and liquidity around the group as and when needed. Bermuda Operations In early July 2008, the Insurance Amendment Act of 2008 was passed, which introduced a number of changes to the Bermuda Insurance Act 1978, such as allowing the Bermuda Monetary Authority ("BMA") to prescribe standards for an enhanced capital requirement and a capital and solvency return with which insurers and reinsurers must comply. The BSCR employs a standard mathematical model that can relate more accurately the risks undertaken by (re)insurers to the capital that is dedicated to their business. Insurers and reinsurers may adopt the BSCR model or, where an insurer or reinsurer believes that its own internal model better reflects the inherent risk of its business, an in-house model approved by the BMA. Class 4 (re)insurers, such as the Company, were required to implement the new capital requirements under the BSCR model beginning with fiscal years ending on or after December 31, 2009. The Company’s capital requirements for its Bermuda principal operating subsidiaries, XLIB, XL Re and Catlin-Bermuda, under the BSCR are highlighted in the table above. In addition to the BSCR based requirements, the BMA also prescribes minimum liquidity standards which must be met. Under the Insurance Act 1978, amendments thereto and related regulations of Bermuda, Class 4 (re)insurers are prohibited from declaring or paying dividends of more than 25% of each of their prior year’s statutory capital and surplus unless they file with the BMA an affidavit stating that the dividend has not caused the Class 4 (re)insurer to fail to meet its relevant margins. At December 31, 2015 and 2014 , the maximum dividend that our Bermuda Class 4 (re)insurers could pay, without a signed affidavit, having met minimum levels of statutory capital and surplus and liquidity requirements, was approximately $2.8 billion and $1.4 billion , respectively. No Class 4 (re)insurer may reduce its total statutory capital by 15% or more unless it has received the prior approval of the BMA, and it must also submit an affidavit stating that the proposed reduction will not cause it to fail to meet its minimum solvency margin or minimum liquidity ratio. U.S. Operations The Company has two lead property and casualty subsidiaries in the U.S., XLRA and Catlin Specialty Insurance Company ("CSIC"), which are domiciled in New York and Delaware, respectively. Both XLRA and CSIC are the lead companies in their respective insurance pools. Including the pool leaders, these insurance pools include seven and three P&C companies, respectively. Unless permitted by the New York Superintendent of Insurance, XLRA cannot declare or distribute any dividend to shareholders during any twelve month period that exceeds the lesser of 10 percent of XLRA’s statutory policyholders’ surplus or 100 percent of its "adjusted net investment income," as defined. Unless permitted by the Insurance Commissioner of the State of Delaware, CSIC cannot declare or distribute any dividend to shareholders during any twelve month period that exceeds the greater of 10 percent of statutory policyholders' surplus or 100 percent of net income excluding realized gains. The New York State and Delaware State insurance laws also provide that any distribution that is a dividend may only be paid out of statutory earned surplus. At December 31, 2015 and 2014 , XLRA had statutory earned surplus of $31.7 million and $205.5 million , respectively, while CSIC had a statutory earned deficit. At December 31, 2015 , XLRA’s statutory policyholders’ surplus was $2.0 billion , and the maximum amount of dividends XLRA can declare and pay in 2016 , without prior regulatory approval, is $31.7 million . At December 31, 2015 , CSIC's statutory policyholders' surplus was $213.1 million , and no dividends can be declared and paid in 2016 without prior regulatory approval. At December 31, 2015 and 2014 , two and none , respectively, of the seven P&C members of the XLRA insurance pool had a statutory earned deficit. At December 31, 2015 , all three of the P&C members of the CSIC insurance pool had a statutory earned deficit. International Operations The Company’s international principal operating subsidiaries prepare statutory financial statements based on local laws and regulations. Some jurisdictions impose enhanced regulatory requirements on insurance companies while other jurisdictions impose fewer requirements. In some countries, such subsidiaries must obtain licenses issued by governmental authorities to conduct local insurance business. These licenses may be subject to minimum reserves and minimum capital and solvency tests. Jurisdictions may impose fines, censure, and/or impose criminal sanctions for violation of regulatory requirements. The majority of the actual statutory capital outside of the U.S. and Bermuda is held in the U.K. ( $3.0 billion at December 31, 2015 ), Switzerland ( $1.8 billion at December 31, 2015 ) and Ireland ( $1.1 billion at December 31, 2015 ). The Company also has sufficient capital available to meet Funds at Lloyd's requirements of approximately $1.6 billion . Other Restrictions XL-Ireland and XL-Cayman have no operations of their own and their assets consist primarily of investments in subsidiaries. Accordingly, XL-Ireland’s and XL-Cayman’s future cash flows largely depend on the availability of dividends or other permissible payments from subsidiaries as noted above. XL-Ireland is subject to certain legal constraints that affect its ability to pay dividends on or redeem or buyback its ordinary shares. While XL-Ireland’s Articles of Association authorize its board of directors to declare and pay dividends as justified from the profits, under Irish law, XL-Ireland may only pay dividends or buyback or redeem shares using distributable reserves. In addition, no dividend or distribution may be made unless the net assets of XL-Ireland are not less than the aggregate of its share capital plus undistributable reserves and the distribution does not reduce XL-Ireland’s net assets below such aggregate. At December 31, 2015 , XL-Ireland had $2.9 billion in distributable reserves. Prospectively the ability to declare and pay dividends may also be restricted by the provisions of Solvency II as described earlier, in particular as they relate to the regulation of groups. In addition, XL-Cayman is subject to certain constraints that affect its ability to pay dividends on its preferred shares. Under Cayman Islands law, XL-Cayman may not declare or pay a dividend if there are reasonable grounds for believing that XL-Cayman is, or would after the payment be, unable to pay its liabilities as they become due in the ordinary course of business. Also, the terms of XL-Cayman’s preferred shares prohibit declaring or paying dividends on the ordinary shares unless full dividends have been declared and paid on the outstanding preferred shares. Full dividends have been declared and paid on the outstanding preferred shares at December 31, 2015 . At December 31, 2015 , XL-Ireland and XL-Cayman held cash and investments, net of liabilities associated with cash sweeping arrangements, of $11.6 million and $0.9 billion , respectively, compared to $22.4 million and $0.9 billion , respectively, at December 31, 2014 . The ability to declare and pay dividends may also be restricted by financial covenants in the Company’s credit facilities. The Company was in compliance with all covenants at December 31, 2015 , and the Company currently remains in compliance.

Computation of Earnings Per Ord

Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of earnings per ordinary share and ordinary share equivalent	Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent The following table sets forth the computation of basic and diluted earnings per ordinary share for the years ended December 31, 2015, 2014 and 2013 : (U.S. dollars in thousands, except per share amounts) 2015 2014 2013 Basic earnings per ordinary share and ordinary share equivalents outstanding: Net income (loss) attributable to ordinary shareholders $ 1,207,152 $ 188,340 $ 1,059,916 Weighted average ordinary shares outstanding 286,194 267,103 287,801 Basic earnings per ordinary share and ordinary share equivalents outstanding $ 4.22 $ 0.71 $ 3.68 Diluted earnings per ordinary share and ordinary share equivalents outstanding: Weighted average ordinary shares outstanding – basic 286,194 267,103 287,801 Impact of share based compensation 4,805 4,424 4,268 Weighted average ordinary shares outstanding – diluted 290,999 271,527 292,069 Diluted earnings per ordinary share & ordinary share equivalents outstanding $ 4.15 $ 0.69 $ 3.63 Dividends per ordinary share $ 0.72 $ 0.64 $ 0.56 For the years ended December 31, 2015, 2014 and 2013 , ordinary shares available for issuance under share-based compensation plans of 2.5 million , 5.5 million and 6.0 million , respectively, were not included in the calculation of diluted earnings per share because the assumed exercise or issuance of such shares would be anti-dilutive.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related party transactions	Related Party Transactions (a) Investment Manager Affiliates At December 31, 2015 and 2014 , the Company owned minority stakes in six independent investment management companies ("Investment Manager Affiliates") that are actively managing client capital and seeking growth opportunities. The Company seeks to develop relationships with specialty investment management organizations, generally acquiring an equity interest in the business. The Company also invests in certain of the funds and limited partnerships and other legal entities managed by these affiliates and through these funds and partnerships pays management and performance fees to the Company's Investment Manager Affiliates. In addition, at December 31, 2015 and 2014 , the company owned minority stakes in two and one independent firm(s) that provide technology and other services to alternative asset managers and allocators, respectively, and the results of the Company's interests in these enterprises are included in Investment Manager Affiliates. The Company pays fees to these Investment Manager Affiliates in exchange for them providing their services to the Company. See Note 7, "Investments in Affiliates ," included herein, for further information. (b) Assumed Reinsurance Contracts In the normal course of business, the Company enters into reinsurance contracts with certain of its other strategic affiliates, or their subsidiaries. During the years ended December 31, 2015, 2014 and 2013 , these contracts resulted in reported net premiums, reported net losses, and reported net acquisition costs as summarized below. (U.S. dollars in thousands) 2015 2014 2013 Reported net premiums $ 42,042 $ 91,261 $ 73,085 Reported net losses $ 13,246 $ 38,927 $ 29,042 Reported net acquisition costs $ 14,682 $ 35,711 $ 25,275 Results through April 1, 2015 include amounts under an assumed reinsurance contract with a wholly-owned subsidiary of ARX, an insurance operating affiliate of the Company to that date. The Company disposed of its investment in ARX on April 1, 2015, and thus, after that date, all amounts under this contract are no longer reported as related party transactions. See Note 3(d), "Acquisitions and Disposals - Sale of Operating Affiliate ." (c) New Ocean Commencing in 2014, several of the Company’s wholly-owned subsidiaries retrocede assumed reinsurance business to special purpose reinsurers that receive capital from funds managed by the Company's subsidiary, New Ocean, as discussed in Note 16, "Variable Interest Entities ." Underwriting administration services are provided to the special purpose reinsurers by other subsidiaries of the Company under service fee agreements, while investment advisory services are provided by New Ocean. During the year ended December 31, 2015 , ceded premiums earned, ceded losses and loss expenses incurred, ceding commission income, and other fee income related to these retrocessional contracts were not material to the Company. (d) New Energy On July 24, 2015, as described in Note 3(b), "Acquisitions and Disposals - New Energy Risk ," the Company completed its acquisition of 63.63% of the additional shares of New Energy for approximately $8.8 million , increasing its majority ownership of the entity to 94.79% . These shares are held within the XL Innovate Fund. A substantial portion of the additional shares were purchased at arm's length directly from the family trusts of a Company employee, based on a market valuation of New Energy performed by an independent third party provider. The remaining 5.21% of equity shares of New Energy held by the family trusts of the employee were then contributed in-kind to XL Innovate Fund based on the share price implied by the independent valuation. Such contribution was made in partial satisfaction of the employee's aggregate 5.21% investment commitment to the Fund and resulted in XL Innovate Fund owning 100% of the net equity of New Energy, and the family trusts of the employee owning a 5.21% non-controlling equity interest in XL Innovate Fund. The employee serves as a member of the board of directors of both New Energy and XL Innovate Fund, and maintains responsibility over the business generated by New Energy. There were no other material transactions between the Company and this employee for the year ended December 31, 2015 .

Unaudited Quarterly Financial D

Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Unaudited quarterly financial data	Unaudited Quarterly Financial Data The following is a summary of the unaudited quarterly financial data for 2015 and 2014 : (U.S. dollars in thousands, except per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Net premiums earned – P&C operations $ 1,319,494 $ 2,063,795 $ 2,405,740 $ 2,375,155 Net premiums earned – Corporate and Other $ 14,506 $ 18,258 $ 17,812 $ 11,665 Underwriting profit (loss) – P&C operations $ 146,836 $ 208,779 $ 114,118 $ 183,458 Net income (loss) attributable to ordinary shareholders $ 36,281 $ 915,039 $ 27,282 $ 228,550 Net income (loss) per ordinary share and ordinary equivalent – basic $ 0.14 $ 3.16 $ 0.09 $ 0.77 Net income (loss) per ordinary share and ordinary equivalent – diluted $ 0.14 $ 3.11 $ 0.09 $ 0.76 2014 Net premiums earned – P&C operations $ 1,412,528 $ 1,438,076 $ 1,453,673 $ 1,413,161 Net premiums earned – Corporate and Other $ 76,311 $ 58,518 $ 19,739 $ 23,064 Underwriting profit (loss) – P&C operations $ 144,874 $ 167,947 $ 144,375 $ 218,850 Net income (loss) attributable to ordinary shareholders $ 255,717 $ (279,260 ) $ 72,384 $ 139,499 Net income (loss) per ordinary share and ordinary equivalent – basic $ 0.93 $ (1.03 ) $ 0.27 $ 0.54 Net income (loss) per ordinary share and ordinary equivalent – diluted $ 0.91 $ (1.03 ) $ 0.27 $ 0.53

Schedule I - Consolidated Summa

Schedule I - Consolidated Summary of Investments - other than Investments in Related Parties	12 Months Ended
	Dec. 31, 2015
Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I - Consolidated summary of investments - other than investments in related parties	SCHEDULE I CONSOLIDATED SUMMARY OF INVESTMENTS – OTHER THAN INVESTMENTS IN RELATED PARTIES AT DECEMBER 31, 2015 AND 2014 2015 2014 (U.S. dollars in thousands) Cost or Amortized Cost (1) Fair Value Amount Presented in the Balance Sheet Cost or Amortized Cost (1) Fair Value Amount Presented in the Balance Sheet Fixed Maturities – AFS - Excluding Life Funds Withheld Assets: U.S. Government and Government Agency-Related/Supported $ 5,047,621 $ 5,065,637 $ 5,065,637 $ 2,100,851 $ 2,171,953 $ 2,171,953 Corporate - Financials 3,535,830 3,561,909 3,561,909 2,687,797 2,761,916 2,761,916 Corporate - Non-Financials 6,867,525 6,900,447 6,900,447 5,774,333 6,016,457 6,016,457 RMBS – Agency 3,697,756 3,757,971 3,757,971 3,625,171 3,728,576 3,728,576 RMBS – Non-Agency 319,876 328,540 328,540 404,398 427,351 427,351 CMBS 401,713 405,316 405,316 1,033,819 1,052,544 1,052,544 CDO 41,679 32,410 32,410 717,544 692,034 692,034 Other asset-backed securities 1,164,426 1,168,572 1,168,572 1,028,528 1,065,293 1,065,293 U.S. States and political subdivisions of the States 2,514,048 2,632,070 2,632,070 1,892,566 2,021,272 2,021,272 Non-U.S. Sovereign Government, Supranational and Government-Related 5,249,148 5,251,614 5,251,614 4,162,425 4,240,073 4,240,073 Total Fixed maturities – AFS $ 28,839,622 $ 29,104,486 $ 29,104,486 $ 23,427,432 $ 24,177,469 $ 24,177,469 Equity securities 834,079 878,919 878,919 763,833 868,292 868,292 Short-term investments 618,851 617,390 617,390 257,221 256,727 256,727 Total Investments - AFS - Excluding Life Funds Withheld Assets 30,292,552 30,600,795 30,600,795 24,448,486 25,302,488 25,302,488 Fixed Maturities - AFS - Life Funds Withheld Assets U.S. Government and Government agency-Related/Supported 10,721 12,742 12,742 14,866 18,724 18,724 Corporate - Financials 531,016 598,236 598,236 701,587 801,019 801,019 Corporate - Non-Financials 1,132,926 1,308,628 1,308,628 1,706,262 2,016,961 2,016,961 RMBS – Agency 591 752 752 3,301 3,782 3,782 RMBS – Non-Agency 24,401 26,953 26,953 71,075 85,335 85,335 CMBS 107,968 122,481 122,481 168,886 193,167 193,167 Other asset-backed securities 132,674 149,795 149,795 238,168 273,541 273,541 Non-U.S. Sovereign Government, Supranational and Government-Related 737,735 933,516 933,516 1,397,194 1,789,036 1,789,036 Total Fixed maturities - AFS - Life Funds Withheld Assets 2,678,032 3,153,103 3,153,103 4,301,339 5,181,565 5,181,565 Total Investments - AFS 32,970,584 33,753,898 33,753,898 28,749,825 30,484,053 30,484,053 Fixed maturities - Trading U.S. Government and Government-Related/Supported 4,957 4,990 4,990 — — — Corporate - Financials 344,070 335,956 335,956 — — — Corporate - Non-Financials 509,441 493,621 493,621 1,180 1,171 1,171 RMBS - Agency 370 368 368 — — — CMBS 4,874 4,803 4,803 — — — Other asset-backed securities 26,405 25,700 25,700 — — — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 373,492 370,261 370,261 — — — Total Fixed maturities - Trading 1,263,609 1,235,699 1,235,699 1,180 1,171 1,171 Short-term investments 60,176 60,330 60,330 — — — Total investments - Trading 1,323,785 1,296,029 1,296,029 1,180 1,171 1,171 Other investments 1,197,674 1,445,793 1,433,057 1,002,871 1,265,682 1,248,439 Total investments other than investments in related parties $ 35,492,043 $ 36,495,720 $ 36,482,984 $ 29,753,876 $ 31,750,906 $ 31,733,663 ____________ (1) Investments in fixed maturities, short-term investments and held to maturity are shown at amortized cost.

Schedule II - Condensed Financi

Schedule II - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule II - Condensed financial information of registrant	SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED BALANCE SHEETS – PARENT COMPANY ONLY AT DECEMBER 31, 2015 AND 2014 (U.S. dollars in thousands) 2015 2014 ASSETS Cash and cash equivalents $ 11,557 $ 22,443 Amounts due from subsidiaries 33,417 — Investments in subsidiaries on an equity basis 11,648,673 10,195,445 Other assets 2,748 3,017 Total assets $ 11,696,395 $ 10,220,905 LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities: Amounts due to subsidiaries $ — $ 166,782 Accounts payable and accrued liabilities 19,316 20,372 Total liabilities $ 19,316 $ 187,154 Commitments and Contingencies Shareholders’ Equity: Class A ordinary shares, 999,990,000 authorized, par value $0.01; issued and outstanding: (2015: 294,745,045; 2014: 255,182,955) $ 2,947 $ 2,552 Additional paid in capital 8,910,167 7,359,102 Accumulated other comprehensive income 686,616 1,484,458 Retained earnings (deficit) 2,077,349 1,187,639 Total shareholders’ equity $ 11,677,079 $ 10,033,751 Total liabilities and shareholders’ equity $ 11,696,395 $ 10,220,905 See accompanying Notes to Condensed Financial Information of Registrant XL GROUP PLC SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT STATEMENT OF INCOME AND COMPREHENSIVE INCOME – PARENT COMPANY ONLY FOR THE YEARS ENDED DECEMBER 31, 2015, 2014 AND 2013 (U.S. dollars in thousands) 2015 2014 2013 Net investment income $ 169 $ 275 $ 24 Total revenues $ 169 $ 275 $ 24 Operating expenses $ 46,340 $ 9,646 $ 11,699 Foreign exchange (gains) losses (345 ) 127 243 Interest expense 11 5 2 Total expenses $ 46,006 $ 9,778 $ 11,944 Income (loss) before income tax $ (45,837 ) $ (9,503 ) $ (11,920 ) Equity in net earnings (losses) of subsidiaries (dividends were: 2015: $764,277; 2014: $858,521; 2013: $617,719) 1,253,609 197,843 1,071,836 Provision for income tax 620 — — Net income (loss) attributable to ordinary shareholders $ 1,207,152 $ 188,340 $ 1,059,916 Net income (loss) $ 1,207,152 $ 188,340 $ 1,059,916 Change in net unrealized gains (losses) on investments - excluding Life Funds Withheld Assets, net of tax (530,030 ) 434,051 (750,755 ) Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax — 424,861 — Change in adjustments related to future policy benefit reserves, net of tax 170,688 (400,456 ) (44,660 ) Change in net unrealized gains (losses) on investments - Life Funds Withheld Assets, net of tax (421,604 ) 274,083 — Change in net unrealized gains (losses) on affiliate and investments, net of tax (6,074 ) 35,143 26,637 Change in OTTI losses recognized in other comprehensive income, net of tax 18,545 13,143 32,181 Change in underfunded pension liability (3,852 ) (7,550 ) 7,653 Change in value of cash flow hedge (200 ) 255 439 Foreign currency translation adjustments (25,315 ) (25,729 ) (54,858 ) Comprehensive income (loss) $ 409,310 $ 936,141 $ 276,553 See accompanying Notes to Condensed Financial Information of Registrant XL GROUP PLC SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT STATEMENT OF CASH FLOWS – PARENT COMPANY ONLY FOR THE YEARS ENDED DECEMBER 31, 2015, 2014 AND 2013 (U.S. dollars in thousands) 2015 2014 2013 Net income (loss) $ 1,207,152 $ 188,340 $ 1,059,916 Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Equity in (earnings) loss of subsidiaries (1,253,609 ) (197,843 ) (1,071,836 ) Share based compensation (1) 74,431 81,287 46,489 Amounts due to (from) subsidiaries (200,199 ) (23,819 ) 104,590 Dividends received from subsidiaries 764,277 858,521 617,719 Other (30,584 ) (10,632 ) (16,570 ) Total adjustments $ (645,684 ) $ 707,514 $ (319,608 ) Net cash provided by (used in) operating activities $ 561,468 $ 895,854 $ 740,308 Cash flows provided by (used in) investing activities: Purchase of Catlin Group Limited $ (2,287,579 ) $ — $ — Proceeds from sale of subsidiary 2,317,699 — — Returns of capital from subsidiaries 65,037 79,086 84,589 Net cash provided by (used in) investing activities $ 95,157 $ 79,086 $ 84,589 Cash flows provided by (used in) financing activities: Proceeds from issuance of ordinary shares and exercise of stock options $ 9,976 $ 6,367 $ 12,623 Dividends paid (208,516 ) (169,620 ) (160,155 ) Buybacks of ordinary shares (468,971 ) (801,953 ) (675,617 ) Net cash provided by (used in) financing activities $ (667,511 ) $ (965,206 ) $ (823,149 ) Net change in cash and cash equivalents (10,886 ) 9,734 1,748 Cash and cash equivalents – beginning of period 22,443 12,709 10,961 Cash and cash equivalents – end of period $ 11,557 $ 22,443 $ 12,709 ____________ (1) Includes cash collected from subsidiaries in the amounts of $60.1 million , $59.2 million and $33.9 million , respectively, for the years ended December 31, 2015, 2014 and 2013 . See accompanying Notes to Condensed Financial Information of Registrant XL GROUP PLC SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT NOTES TO THE FINANCIAL STATEMENTS - PARENT COMPANY ONLY FOR THE YEARS ENDED DECEMBER 31, 2015, 2014 AND 2013 1. Presentation The condensed financial information of XL Group plc reflects its directly wholly-owned subsidiaries using the equity method of accounting. To facilitate period-to-period comparisons, certain reclassifications have been made to prior year condensed financial statement amounts to conform to the current year presentation. There has been no effect on net income from this change in presentation. 2. Dividends and Returns of Capital For the indicated years ended December 31, XL Group plc received dividends and/or returns of capital from XLIT Ltd. a wholly-owned subsidiary. (U.S. dollars in million) 2015 2014 2013 Dividends and returns of capital $ 829 $ 940 $ 702 3. Commitments and Guarantees See Item 8, Note 17, "Commitments and Contingencies ," to the Consolidated Financial Statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2015 .

Schedule IV - Reinsurance

Schedule IV - Reinsurance	12 Months Ended
	Dec. 31, 2015
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
Schedule IV - Reinsurance	SCHEDULE IV REINSURANCE FOR THE YEARS ENDED DECEMBER 31, 2015, 2014 AND 2013 (U.S. dollars in thousands) Gross Amount Ceded to Other Companies Assumed from Other Companies Net Amount Percentage of Amount Assumed to Net 2015 Life reinsurance in force (1) $ — $ 62,290,992 $ 63,158,304 $ 867,312 N/M Premiums Earned: Property and casualty operations $ 7,717,173 $ 3,018,410 $ 3,465,421 $ 8,164,184 42.4 % Life operations — 247,675 309,916 62,241 497.9 % Total premiums earned $ 7,717,173 $ 3,266,085 $ 3,775,337 $ 8,226,425 45.9 % 2014 Life reinsurance in force (1) $ — $ 46,947,677 $ 68,854,340 $ 21,906,663 314.3 % Premiums Earned: Property and casualty operations $ 5,173,403 $ 1,799,294 $ 2,343,329 $ 5,717,438 41.0 % Life operations — 155,804 333,436 177,632 187.7 % Total premiums earned $ 5,173,403 $ 1,955,098 $ 2,676,765 $ 5,895,070 45.4 % 2013 Life reinsurance in force (1) $ — $ 378,391 $ 77,917,632 $ 77,539,241 100.5 % Premiums Earned: Property and casualty operations $ 4,966,207 $ 1,315,369 $ 2,363,261 $ 6,014,099 39.3 % Life operations — 28,920 324,342 295,422 109.8 % Total premiums earned $ 4,966,207 $ 1,344,289 $ 2,687,603 $ 6,309,521 42.6 % ____________ (1) Represents the sum face value outstanding of the in force life reinsurance policies. * N/M - Not Meaningful

Schedule VI - Supplementary Inf

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations	12 Months Ended
	Dec. 31, 2015
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Schedule VI - Supplementary information concerning property/casualty (re)insurance operations	SCHEDULE VI SUPPLEMENTAL INFORMATION CONCERNING PROPERTY/CASUALTY (RE)INSURANCE OPERATIONS FOR THE YEARS ENDED DECEMBER 31, 2015, 2014 AND 2013 (U.S. dollars in thousands) Deferred Acquisition Costs and Value of Business Acquired Reserves for Losses and Loss Expenses Reserves for Unearned Premiums Net Earned Premiums Net Investment Income Losses and Loss Expenses incurred related to Net Paid Losses and Loss Expenses Amortization of Deferred Acquisition Costs Net Premiums Written Current Year Prior Year 2015 $ 893,111 $ 25,439,744 $ 7,043,383 $ 8,164,184 $ 644,312 $ 5,072,830 $ (306,630 ) $ 5,374,652 $ 1,306,654 $ 7,888,824 2014 $ 357,067 $ 19,353,243 $ 3,973,159 $ 5,717,438 $ 642,492 $ 3,513,465 $ (255,072 ) $ 3,821,335 $ 724,003 $ 5,767,209 2013 $ 537,473 $ 20,481,065 $ 3,846,568 $ 6,014,099 $ 671,071 $ 4,021,353 $ (289,889 ) $ 3,828,139 $ 882,658 $ 5,903,982

Significant Accounting Polici38

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of preparation	These consolidated financial statements include the accounts of the Company and all of its subsidiaries. These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). To facilitate period-to-period comparisons, certain reclassifications have been made to prior year consolidated financial statement amounts to conform to the current year presentation. There was no effect on net income from this change in presentation.
Use of estimates	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company’s most significant areas of estimation include: ▪ unpaid losses and loss expenses and unpaid losses and loss expenses recoverable; ▪ future policy benefit reserves; ▪ valuation and other-than-temporary impairments of investments; ▪ income taxes; ▪ reinsurance premium estimates; and ▪ carrying value of goodwill and intangible assets. While management believes that the amounts included in the consolidated financial statements reflect the Company’s best estimates and assumptions, actual results could differ from these estimates.
Basis of fair value measurement	Financial Instruments Subject to Fair Value Measurements Accounting guidance over fair value measurements requires that a fair value measurement reflect the assumptions market participants would use in pricing an asset or liability based on the best information available. Assumptions include the risks inherent in a particular valuation technique (such as a pricing model) and/or the risks inherent in the inputs to the model. The fair value of a financial instrument is the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (the "exit price"). Instruments that the Company owns ("long positions") are marked to bid prices and instruments that the Company has sold but not yet purchased ("short positions") are marked to offer prices. Fair value measurements are not adjusted for transaction costs. Basis of Fair Value Measurement Fair value measurements accounting guidance also establishes a fair value hierarchy that prioritizes the inputs to the respective valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). An asset or liability’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. The three levels of the fair value hierarchy are described further below: ▪ Level 1 - Quoted prices in active markets for identical assets or liabilities (unadjusted); no blockage factors. ▪ Level 2 - Other observable inputs (quoted prices in markets that are not active or inputs that are observable either directly or indirectly)—include quoted prices for similar assets/liabilities (adjusted) other than quoted prices in Level 1; quoted prices in markets that are not active; or other inputs that are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. ▪ Level 3 - Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Unobservable inputs reflect the reporting entity’s own assumptions about the assumptions that market participants would use in pricing the asset or liability. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Details on assets and liabilities that have been included under the requirements of authoritative guidance on fair value measurements to illustrate the bases for determining the fair values of these items held by the Company are included in each respective section of this note. Fair values of investments and derivatives are based on published market values if available, estimates of fair values of similar issues, or estimates of fair values provided by independent pricing services and brokers. Fair values of financial instruments for which quoted market prices are not available or for which the Company believes current trading conditions represent distressed markets are based on estimates using present value or other valuation techniques. The fair values estimated using such techniques are significantly affected by the assumptions used, including the discount rates and the estimated amounts and timing of future cash flows. In such instances, the derived fair value estimates cannot be substantiated by comparison to independent markets and are not necessarily indicative of the amounts that would be realized in a current market exchange.
Investments	Investments - Available For Sale Investments that are considered available for sale (comprised of fixed maturities, equity securities and short-term investments) are carried at fair value. The fair values for available for sale investments are generally sourced from third parties. The fair values of fixed income securities are based upon quoted market values where available, "evaluated bid" prices provided by third party pricing services ("pricing services") where quoted market values are not available, or by reference to broker or underwriter bid indications where pricing services do not provide coverage for a particular security. To the extent the Company believes current trading conditions represent distressed transactions, the Company may elect to utilize internally generated models. It is common industry practice to utilize pricing services as a source for determining the fair values of investments where the pricing services are able to obtain sufficient market corroborating information to allow them to produce a valuation at a reporting date. In addition, in the majority of cases, although a value may be obtained from a particular pricing service for a security or class of similar securities, these values are corroborated against values provided by other pricing services. The pricing services use market approaches to valuations using primarily Level 2 inputs in the vast majority of valuations, or some form of discounted cash flow analysis, to obtain investment values for a small percentage of fixed income securities for which they provide a price. Standard inputs to the valuations provided by the pricing services listed in approximate order of priority for use when available include: reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data. The pricing services may prioritize inputs differently on any given day for any security, and not all inputs listed are available for use in the evaluation process on any given day for each security evaluation; however, the pricing services also monitor market indicators, customer feedback through a price challenge process and industry and economic events. Information of this nature is a trigger to acquire further corroborating market data. When these inputs are not available, they identify "buckets" of similar securities (allocated by asset class types, sectors, sub-sectors, contractual cash flows/structure, and credit rating characteristics) and apply some form of matrix or other modeled pricing to determine an appropriate security value which represents their best estimate as to what a buyer in the marketplace would pay for a security in a current sale. Prices provided by independent pricing services and independent broker quotes can vary widely even for the same security. The use of different methodologies and assumptions may have a material effect on the estimated fair value amounts. While the Company receives values for the majority of the investment securities it holds from pricing services, it is ultimately management’s responsibility to determine whether the values received and recorded in the financial statements are representative of appropriate fair value measurements. Broker/dealer quotations are used to value fixed maturities where prices are unavailable from pricing services due to factors specific to the security such as limited liquidity, lack of current transactions, or trades only taking place in privately negotiated transactions. These are considered Level 3 valuations, as significant inputs utilized by brokers may be difficult to corroborate with observable market data, or sufficient information regarding the specific inputs utilized by the broker was not available to support a Level 2 classification. Equity securities include investments in open end mutual funds and shares of publicly traded hedge funds. The fair value of equity securities is based upon quoted market values (Level 1), or monthly net asset value statements provided by the investment managers upon which subscriptions and redemptions can be executed (Level 2). Short-term investments include investments due to mature within one year from the date of purchase and are valued using the same external factors and in the same manner as fixed income securities. Changes in the value of investments available for sale are reflected as unrealized gains or losses on investments, and are included in "accumulated other comprehensive income (loss)", on a net of tax basis. All investment transactions are recorded on a trade date basis. Realized gains and losses on sales of equities and fixed income investments are determined on a first-in, first-out basis. Investment income is recognized when earned and includes interest and dividend income together with the amortization of premium and discount on fixed maturities and short-term investments, and is recorded net of related investment expenses. Amortization of discounts on fixed maturities includes amortization to expected recovery values for investments that have previously been recorded as other than temporarily impaired. For mortgage-backed securities, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Prepayment fees or call premiums that are only payable to the Company when a security is called prior to its maturity are earned when received and reflected in net investment income. Investments - Trading Investments for which the company has elected the fair value option are classified as trading. Trading securities are carried at fair value with changes included in "Net realized gains (losses) on investments sold." Interest and dividend income from trading securities are included as a component of "Net investment income - Life Funds Withheld Assets" as all trading securities are held in support of the GreyCastle Life Retro Arrangements as defined in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ." Investments Related to Life Retrocession Arrangements written on a Funds Withheld Basis Designated investments that support the GreyCastle Life Retro Arrangements written on a funds withheld basis ("Life Funds Withheld Assets") entered into in connection with the sale of our life reinsurance subsidiary are classified as either available for sale or trading. Investment results for these assets - including interest income, unrealized gains and losses, and gains and losses from sales - are passed directly to the reinsurer pursuant to a contractual arrangement that is accounted for as a derivative. Changes in the fair value of the embedded derivative associated with the GreyCastle Life Retro Arrangements are recorded in "Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets" on the consolidated statements of income. The fair value of the embedded derivative is included within "Funds withheld on life retrocession arrangements, net of future policy benefit reserves recoverable" on the consolidated balance sheets. Investments In Affiliates Investments in which the Company has significant influence over the operating and financial policies of the investee are classified as investments in affiliates on the Company’s balance sheets and are accounted for under the equity method of accounting. Under this method, the Company records its proportionate share of income or loss from such investments in its results for the period as well as its portion of movements in certain of the investee shareholders’ equity balances. When financial statements of the affiliate are not available on a timely basis to record the Company’s share of income or loss for the same reporting periods as the Company, the most recently available financial statements are used. This lag in reporting is applied consistently. Distributions received from affiliates representing returns on invested capital are recorded as operating cash flows, while distributions representing returns of invested capital or proceeds upon sale of all or a portion of an affiliate are recorded as investing cash flows. The Company generally records its hedge fund and private investment fund affiliates on a one -month and three -month lag, respectively, and its operating affiliates on a three -month lag. Significant influence is generally deemed to exist where the Company has an investment of 20% or more in the common stock of a corporation or an investment of 3% or more in closed-end funds, limited partnerships, limited liability companies ("LLCs") or similar investment vehicles. Significant influence is considered for other strategic investments on a case-by-case basis. Investments in affiliates are not subject to fair value measurement guidance as they are not considered to be fair value measured investments under GAAP. However, impairments associated with investments in affiliates that are deemed to be other-than-temporary are calculated in accordance with fair value measurement guidance and appropriate disclosures included within the financial statements during the period the losses are recorded. Other Investments Contained within this asset class are equity interests in investment funds, limited partnerships and unrated tranches of collateralized debt obligations for which the Company does not have sufficient rights or ownership interests to follow the equity method of accounting. The Company accounts for equity securities that do not have readily determinable market values at estimated fair value as it has no significant influence over these entities. Also included within other investments are structured transactions, which are carried at amortized cost. Fair values for other investments, principally other direct equity investments, investment funds and limited partnerships, are primarily based on the net asset value provided by the investment manager, the general partner or the respective entity, recent financial information, available market data and, in certain cases, management judgment, if required. These entities generally carry their trading positions and investments, the majority of which have underlying securities valued using Level 1 or Level 2 inputs, at fair value as determined by their respective investment managers; accordingly, these investments are generally classified as Level 2. Private equity investments are classified as Level 3. The net unrealized gain or loss on investments, net of tax, is included in "Accumulated other comprehensive income (loss)." Any unrealized loss in value considered by management to be other-than-temporary is charged to income in the period in which it is determined. Overseas deposits include investments in private funds related to Lloyd’s syndicates in which the underlying instruments are primarily fixed maturities. The funds themselves do not trade on an exchange and therefore are not included within available for sale securities. Also included in overseas deposits are restricted balances held by Lloyd’s syndicates for solvency purposes which are primarily invested in cash and cash equivalents. Given the restricted nature of these balances, they are included in other investments on the balance sheets. Each of these investment types is considered a Level 2 valuation. The Company has historically participated in structured transactions. These have included providing cash loans supporting project finance transactions, and providing liquidity facility financing to structured project deals. The Company also invested in a payment obligation with an insurance company. The Company's policy is to value such transactions at amortized cost.
Premiums	Insurance premiums written are recorded in accordance with the terms of the underlying policies. Reinsurance premiums written are recorded at the inception of the policy and are estimated based upon information received from ceding companies and any subsequent differences arising on such estimates are recorded in the period they are determined. For multi-year reinsurance treaties which are payable in annual installments, generally, only the initial annual installment is included as premiums written at policy inception due to the ability of the reinsured to commute or cancel coverage during the term of the policy. The remaining annual installments are included as premiums written at each successive anniversary date within the multi-year term. Premiums are earned on a pro-rata basis over the period the coverage is provided. Unearned premiums represent the portion of premiums written applicable to the unexpired terms of policies in force. Net premiums earned are presented after deductions for reinsurance ceded, as applicable. Mandatory reinstatement premiums are recognized and earned at the time a loss event occurs. Life and annuity premiums from long duration contracts that transfer significant mortality or morbidity risks are recognized as revenue and earned when due from policyholders. Life and annuity premiums from long duration contracts that do not subject the Company to risks arising from policyholder mortality or morbidity are accounted for as investment contracts and presented within deposit liabilities. The Company has periodically written retroactive loss portfolio transfer contracts. These contracts are evaluated to determine whether they meet the established criteria for reinsurance accounting, and, if so, at inception, written premiums are fully earned and corresponding losses and loss expense recognized. The contracts can cause significant variances in gross premiums written, net premiums written, net premiums earned, and net incurred losses in the years in which they are written. Reinsurance contracts sold not meeting the established criteria for reinsurance accounting are recorded using the deposit method.
Acquisition costs	Acquisition costs, which vary with and are directly related to the acquisition of policies, consist primarily of commissions paid to brokers and cedants, and are deferred and amortized over the period during which the premiums are earned. Acquisition costs are shown net of contractual commissions earned on reinsurance ceded. Future earned premiums, the anticipated losses and other costs (and in the case of a premium deficiency, investment income) related to those premiums, are also considered in determining the level of acquisition costs to be deferred.
Reinsurance	In the normal course of business, the Company seeks to reduce the potential amount of loss arising from claims events by reinsuring certain levels of risk assumed in various areas of exposure with other insurers or reinsurers. Reinsurance premiums ceded are expensed (and any commissions recorded thereon are earned) on a monthly pro-rata basis over the period the reinsurance coverage is provided. Ceded unearned reinsurance premiums represent the portion of premiums ceded applicable to the unexpired term of policies in force. Mandatory reinstatement premiums ceded are recorded at the time a loss event occurs. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured policy. Provisions are made for estimated unrecoverable reinsurance. The Company enters into reinsurance agreements with other companies in the normal course of business. All premium and loss-related balances related to reinsurance agreements are reported on a gross basis within our consolidated balance sheets, with the exception of the GreyCastle Life Retro Arrangements written on a funds withheld basis. The future policy benefit reserves recoverable related to these retrocession arrangements are netted against the funds withheld liability owing to the counterparty on the consolidated balance sheets due to the contractual right of offset. During the year ended December 31, 2014, the Company recorded $20 million , net of tax, to premiums earned and associated tax accruals, related to reinstatement premiums due under assumed reinsurance contracts arising from unpaid losses and loss expenses reported in a prior period. We evaluated the quantitative and qualitative aspects of this correction and concluded that the impact of recognizing it during the third quarter of 2014 was not material to the consolidated financial statements, nor is it material to previously issued consolidated financial statements in prior periods.
Fee income and other	Fee income and other includes fees received for insurance and product structuring services provided and is earned over the service period of the contract. Any adjustments to fees earned or the service period are reflected in income in the period when determined.
Other-than-temporary impairments ("OTTI") of available for sale and held to maturity securities	The Company’s process for identifying declines in the fair value of investments that are other-than-temporary involves consideration of several factors. These primary factors include (i) an analysis of the liquidity, business prospects and financial condition of the issuer including consideration of credit ratings, (ii) the significance of the decline, (iii) an analysis of the collateral structure and other credit support, as applicable, of the securities in question, and (iv) for debt securities, whether the Company intends to sell such securities. In addition, the authoritative guidance requires that OTTI for certain asset backed and mortgage backed securities be recognized if the fair value of the security is less than its discounted cash flow value and there has been a decrease in the present value of the expected cash flows since the last reporting period. Where the Company’s analysis of the above factors results in the Company’s conclusion that declines in fair values are other-than-temporary, the cost of the security is written down to discounted cash flow and a portion of the previously unrealized loss is therefore realized in the period such determination is made. If the Company intends to sell an impaired security, or it is more likely than not that it will be required to sell the security before recovery of its amortized cost basis, the impairment is other-than-temporary and is recognized currently in earnings in an amount equal to the entire difference between fair value and amortized cost. In instances in which the Company determines that a credit loss exists but the Company does not intend to sell the security, and it is not more likely than not that the Company will be required to sell the security before the anticipated recovery of its remaining amortized cost basis, the OTTI is separated into (1) the amount of the total impairment related to the credit loss and (2) the amount of the total impairment related to all other factors (i.e. the noncredit portion). The amount of the total OTTI related to the credit loss is recognized in earnings and the amount of the total OTTI related to all other factors is recognized in accumulated other comprehensive loss. The total OTTI is presented in the income statement with an offset for the amount of the total OTTI that is recognized in accumulated other comprehensive income (loss). Absent the intent or requirement to sell a security, if a credit loss does not exist, any impairment is considered to be temporary. The noncredit portion of any OTTI losses on securities classified as available for sale is recorded as a component of other comprehensive income (loss) with an offsetting adjustment to the carrying value of the security. The fair value adjustment could increase or decrease the carrying value of the security. In periods subsequent to the recognition of an OTTI loss, the other-than-temporarily impaired debt security is accounted for as if it had been purchased on the measurement date of the OTTI at an amount equal to the previous amortized cost basis less the credit-related OTTI recognized in earnings. For debt securities for which credit-related OTTI is recognized in earnings, the difference between the new cost basis and the cash flows expected to be collected is accreted into interest income over the remaining life of the security in a prospective manner based on the estimated amount and timing of future estimated cash flows. With respect to securities where the decline in value is determined to be temporary and the security’s amortized cost is not written down, a subsequent decision may be made to sell that security and realize a loss. Subsequent decisions on security sales are made within the context of overall risk monitoring, changing information, market conditions generally and assessing value relative to other comparable securities. We have outsourced a significant portion of the day-to-day management of the Company’s investment portfolio to third party investment manager service providers. While these investment manager service providers may, at a given point in time, believe that the preferred course of action is to hold securities with unrealized losses that are considered temporary until such losses are recovered, the dynamic nature of the portfolio management may result in a subsequent decision to sell the security and realize the loss, based upon a change in market and other factors described above. The Company believes that subsequent decisions to sell such securities are consistent with the classification of the Company’s portfolio as available for sale. There are risks and uncertainties associated with determining whether declines in the fair value of investments are other-than-temporary. These include subsequent significant changes in general economic conditions as well as specific business conditions affecting particular issuers, subjective assessment of issue-specific factors (seniority of claims, collateral value, etc.), future financial market effects, stability of foreign governments and economies, future rating agency actions and significant disclosure of accounting, fraud or corporate governance issues that may adversely affect certain investments. In addition, significant assumptions and management judgment are involved in determining if the decline is other-than-temporary. If management determines that a decline in fair value is temporary, then a security’s value is not written down at that time. However, there are potential effects upon the Company’s future earnings and financial position should management later conclude that some of the current declines in the fair value of the investments are other-than-temporary declines.
Derivative instruments	The Company recognizes all derivatives as either assets or liabilities in the balance sheets and measures those instruments at fair value. Except for the embedded derivative associated with the GreyCastle Life Retro Arrangements discussed above within (c) "Investments Related to Life Retrocession Arrangements written on a Funds Withheld Basis," the changes in fair value of derivatives are shown in the consolidated statements of income as "net realized and unrealized gains and losses on derivative instruments," unless the derivatives are designated as hedging instruments. The accounting for derivatives that are designated as hedging instruments is discussed below. Changes in fair value of derivatives may create volatility in the Company’s results of operations from period to period. Amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) are offset against net fair value amounts recognized in the consolidated balance sheets for derivative instruments executed with the same counterparty under the same netting arrangement to the extent that the Company intends to settle the amounts on a net basis. Derivative contracts can be exchange-traded or over-the-counter ("OTC"). Exchange-traded derivatives (futures and options) typically fall within Level 1 of the fair value hierarchy depending on whether they are deemed to be actively traded or not. OTC derivatives are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market clearing transactions, broker or dealer quotations or alternative pricing sources where an understanding of the inputs utilized in arriving at the valuations is obtained. Where models are used, the selection of a particular model to value an OTC derivative depends upon the contractual terms and specific risks inherent in the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices, yield curves, credit curves, measures of volatility, prepayment rates and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as generic forwards, interest rate swaps and options, model inputs can generally be verified and model selection does not involve significant management judgment. Such instruments comprise the majority of derivatives held by the Company and are typically classified within Level 2 of the fair value hierarchy. Certain OTC derivatives trade in less liquid markets with limited pricing information, or required model inputs that are not directly market corroborated, which causes the determination of fair value for these derivatives to be inherently more subjective. Accordingly, such derivatives are classified within Level 3 of the fair value hierarchy. The valuations of less standard or liquid OTC derivatives are typically based on Level 1 and/or Level 2 inputs that can be observed in the market, as well as unobservable Level 3 inputs. Level 1 and Level 2 inputs are regularly updated to reflect observable market changes. Level 3 inputs are only changed when corroborated by evidence such as similar market transactions, pricing services and/or broker or dealer quotations. The Company conducts its non-hedging derivatives activities in three main areas: investment related derivatives, credit derivatives and other non-investment related derivatives. The Company uses derivative instruments, primarily interest rate swaps, to manage the interest rate exposure associated with certain assets and liabilities. These derivatives are recorded at fair value. On the date the derivative contract is entered into, the Company may designate the derivative as: a hedge of the fair value of a recognized asset or liability ("fair value" hedge); a hedge of the variability in cash flows of a forecasted transaction or of amounts to be received or paid related to a recognized asset or liability ("cash flow" hedge); or a hedge of a net investment in a foreign operation; or the Company may not designate any hedging relationship for a derivative contract. Fair Value Hedges Changes in the fair value of a derivative that is designated and qualifies as a fair value hedge, along with the changes in the fair value of the hedged asset or liability that is attributable to the hedged risk, are recorded in current period earnings (through "net realized and unrealized gains and losses on derivative instruments") with any differences between the net change in fair value of the derivative and the hedged item representing the hedge ineffectiveness. Periodic derivative net coupon settlements are recorded in net investment income with the exception of hedges of Company issued debt, which are recorded in interest expense. The Company may designate fair value hedging relationships where interest rate swaps are used to hedge the changes in the fair value of certain fixed rate liabilities and fixed maturity securities due to changes in the designated benchmark interest rate. Cash Flow Hedges Changes in the fair value of a derivative that is designated and qualifies as a cash flow hedge are recorded in accumulated other comprehensive income ("AOCI") and are reclassified into earnings when the variability of the cash flow of the hedged item impacts earnings. Gains and losses on derivative contracts that are reclassified from AOCI to current period earnings are included in the line item in the consolidated statements of operations in which the cash flows of the hedged item are recorded. Any hedge ineffectiveness is recorded immediately in current period earnings as "net realized and unrealized gains and losses on derivative instruments." Periodic derivative net coupon settlements are recorded in net investment income. The Company may designate cash flow hedging relationships where interest rate swaps are used to mitigate interest rate risk associated with anticipated issuances of debt or other forecasted transactions. Hedges of the Net Investment in a Foreign Operation Changes in the fair value of a derivative used as a hedge of a net investment in a foreign operation, to the extent effective as a hedge, are recorded in the foreign currency translation adjustments account within AOCI. Cumulative changes in fair value recorded in AOCI are reclassified into earnings upon the sale or complete or substantially complete liquidation of the foreign entity. Any hedge ineffectiveness is recorded immediately in current period earnings as "net realized and unrealized gains and losses on derivative instruments." Hedge Documentation and Effectiveness Testing To qualify for hedge accounting treatment, a derivative must be highly effective in mitigating the designated changes in value or cash flow of the hedged item. At hedge inception, the Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking each hedge transaction. The documentation process includes linking derivatives that are designated as fair value, cash flow, or net investment hedges to specific assets or liabilities on the balance sheet or to specific forecasted transactions. The Company also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in fair values or cash flows of hedged items. In addition, certain hedging relationships are considered highly effective if the changes in the fair value or discounted cash flows of the hedging instrument are within a ratio of 80-125% of the inverse changes in the fair value or discounted cash flows of the hedged item. Hedge ineffectiveness is measured using qualitative and quantitative methods. Qualitative methods may include comparison of critical terms of the derivative to the hedged item. Depending on the hedging strategy, quantitative methods may include the "Change in Variable Cash Flows Method," the "Change in Fair Value Method," the "Hypothetical Derivative Method" or the "Dollar Offset Method." Discontinuance of Hedge Accounting The Company discontinues hedge accounting prospectively when it determines that the derivative is no longer highly effective in offsetting changes in the fair value or cash flows of a hedged item; the derivative is dedesignated as a hedging instrument; or the derivative expires or is sold, terminated or exercised. When hedge accounting is discontinued because it is determined that the derivative no longer qualifies as an effective fair-value hedge, the derivative continues to be carried at fair value on the balance sheets with changes in its fair value recognized in current period earnings through "net realized and unrealized gains and losses on derivative instruments." When hedge accounting is discontinued because the Company becomes aware that it is not probable that the forecasted transaction will occur, the derivative continues to be carried on the balance sheets at its fair value, and gains and losses that were accumulated in AOCI are recognized immediately in earnings.
Cash equivalents	Cash equivalents include fixed interest deposits placed with a maturity of under 90 days when purchased. Bank deposits are not considered to be fair value measurements and as such are not subject to the authoritative guidance on fair value measurement disclosures. Money market funds are classified as Level 1 as these instruments are considered actively traded; however, certificates of deposit are classified as Level 2.
Restricted cash	Restricted cash represents cash and cash equivalents that the Company is a) holding for the benefit of a third party and is legally or contractually restricted as to withdrawal or usage for general corporate purposes; and b) not replaceable by another type of asset other than cash or cash equivalents, under the terms of the Company's contractual arrangements with such third parties.
Foreign currency translation	Assets and liabilities of foreign operations whose functional currency is not the U.S. dollar are translated at prevailing year end exchange rates. Revenue and expenses of such foreign operations are translated at monthly average exchange rates during the year. The net effect of the translation adjustments for foreign operations, net of applicable deferred income taxes, as well as any gains or losses on intercompany balances for which settlement is not planned or anticipated in the foreseeable future, are included in "accumulated other comprehensive income (loss)." Monetary assets and liabilities denominated in currencies other than the functional currency of the applicable entity are revalued at the exchange rate in effect at the balance sheet date and revenues and expenses are translated at the exchange rate on the date the transaction occurs with the resulting foreign exchange gains and losses on settlement or revaluation recognized in income.
Goodwill and other intangible assets	The Company has recorded goodwill in connection with various acquisitions in the current and prior years. Goodwill represents the excess of the purchase price over the fair value of net assets acquired. In accordance with GAAP, the Company tests goodwill for potential impairment annually as of June 30, and between annual tests if an event occurs or circumstances change that may indicate that potential exists for the fair value of a reporting unit to be reduced to a level below its carrying amount. The Company tests for impairment at the reporting unit level in accordance with the authoritative guidance on intangibles and goodwill. The Company has organized its goodwill into two reporting units, reflecting its two segments. The Company’s indefinite-lived intangible assets consist primarily of acquired insurance and reinsurance licenses, plus Lloyd's syndicate capacity. These assets are deemed to have indefinite useful lives and are therefore not subject to amortization. In accordance with GAAP, the Company tests non-amortized intangible assets for potential impairment annually, or more frequently if events or changes in circumstances indicate that the asset might be impaired. If the carrying value of a non-amortized intangible asset is in excess of its fair value, the asset must be written down to its fair value through the recognition of an impairment charge to earnings. All of the Company’s depreciable or amortizable intangible and other long-lived assets such as trade names, distribution networks, premises, equipment, agency relationships, and acquired or internally-developed software, are carried at net book value, and are depreciated or amortized on a straight-line basis over their estimated useful lives. The amortization periods approximate the period over which the Company expects to generate future net cash inflows from the use of these assets. All of these assets are subject to impairment testing in accordance with authoritative guidance for the impairment or disposal of long-lived assets when events or conditions indicate that the carrying value of an asset may not be fully recoverable from future cash flows.
Variable interest entities ('VIEs')	Investments or other interests that absorb portions of an entity’s expected losses or receive portions of the entity’s expected residual returns are called variable interests. Entities in which the equity investors, as a group, do not have the characteristic of a controlling financial interest, or that do not have sufficient equity at risk to allow them to finance their own activities without additional financial support are referred to as VIEs. A VIE must be consolidated by its primary beneficiary, which is the variable interest holder that is determined to have the controlling financial interest in the entity. Based upon the nature of the VIE, this is either the entity that has both: a) the power to direct the VIE’s activities that most significantly impact its economic performance, and b) the obligation to absorb losses or receive benefits of the VIE that could potentially be significant to it; or it is the reporting entity that will absorb a majority of the VIE's expected losses, receive a majority of the VIE's expected residual returns, or both.
Non-controlling interests	Non-controlling shareholders' interests are presented separately in the Company's Consolidated Balance Sheets and Consolidated Statements of Shareholders' Equity as required under GAAP. The net loss (income) attributable to non-controlling interests is presented separately in the Company's Consolidated Statements of Comprehensive Income.
Losses and loss expenses	Unpaid losses and loss expenses include reserves for reported unpaid losses and loss expenses and for losses incurred but not reported. The reserve for reported unpaid losses and loss expenses for the Company’s property and casualty operations is established by management based on claims reported from insureds or amounts reported from ceding companies, and represent the estimated ultimate cost of events or conditions that have been reported to or specifically identified by the Company. The reserve for losses incurred but not reported is estimated by management based on loss development patterns determined by reference to the Company’s underwriting practices, the policy form, type of program and historical experience. The Company’s actuaries employ a variety of generally accepted methodologies to determine estimated ultimate loss reserves, including the "Bornhuetter-Ferguson incurred loss method" and frequency and severity approaches. Certain workers’ compensation and certain U.K. bodily injury liabilities are considered fixed and determinable and are discounted. Management believes that the reserves for unpaid losses and loss expenses are sufficient to cover losses that fall within coverages assumed by the Company. However, there can be no assurance that losses will not exceed the Company’s total reserves. The methodology of estimating loss reserves is periodically reviewed to ensure that the assumptions made continue to be appropriate and any adjustments resulting from such reviews are reflected in income in the year in which the adjustments are made.
Deposit liabilities	Contracts entered into by the Company that are not deemed to transfer significant underwriting risk and/or timing risk are accounted for as deposits, whereby liabilities are initially recorded at an amount equal to the assets received. The Company uses a portfolio rate of return of equivalent duration to the liabilities in determining risk transfer. An initial accretion rate is established based on actuarial estimates whereby the deposit liability is increased to the estimated amount payable over the term of the contract. The deposit accretion rate is the rate of return required to fund expected future payment obligations (this is equivalent to the "best estimate" of future cash flows), which are determined actuarially based upon the nature of the underlying indemnifiable losses. Accretion of the liability is recorded as interest expense. The Company periodically reassesses the estimated ultimate liability. Any changes to this liability are reflected as adjustments to interest expense to reflect the cumulative effect of the period the contract has been in force, and by an adjustment to the future accretion rate of the liability over the remaining estimated contract term.
Future policy benefit reserves	The Company estimates the present value of future policy benefits related to long duration contracts using assumptions for investment yields, mortality, and expenses, including a provision for adverse deviation. The assumptions used to determine future policy benefit reserves are best estimate assumptions that are determined at the inception of the contracts and are locked-in throughout the life of the contract unless a premium deficiency develops. As the experience on the contracts emerges, the assumptions are reviewed. If such review would produce reserves in excess of those currently held, then the locked-in assumptions will be revised and a claim and policy benefit is recognized at that time. The Company includes the cost of reinsurance in its premium deficiency considerations. Certain life insurance and annuity contracts provide the holder with a guarantee that the benefit received upon death will be no less than a minimum prescribed amount. The contracts are accounted for in accordance with GAAP, which requires that the best estimate of future experience be combined with actual experience to determine the benefit ratio used to calculate the policy benefit reserve.
Income taxes	The Company utilizes the asset and liability method of accounting for income taxes. Under this method, deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The realizability of deferred tax assets is evaluated based upon management's assessment of taxable income in prior eligible carryback years, future reversals of existing taxable temporary differences, future taxable income exclusive of reversing temporary differences and carryforwards, and tax planning strategies that would, if necessary, be implemented. A valuation allowance may have to be established for any portion of a deferred tax asset that management believes will not be realized. The Company recognizes the tax benefit from an uncertain tax position taken only if it is more likely than not that the tax position will be sustained upon examination by the relevant tax authority, based on our interpretation of and judgment of the relevant tax law. The Company reviews its uncertain tax positions on a quarterly basis. Tax positions that meet the more likely than not threshold are measured using a probability weighted approach, whereby the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement is recognized. The Company recognizes interest and penalties on underpaid tax as a component of income tax expense. The Company’s investment income is allocated to applicable branch operations and is taxable in certain jurisdictions. The method of allocating this income may be different for tax reporting as compared to GAAP. The Company records the tax effects of this allocation entirely through operations.
Stock plans	At December 31, 2015 , the Company had several stock-based performance incentive programs, which are described more fully in Note 18, "Share Capital ." Stock-based compensation issued under these plans generally has a life of not longer than ten years and vests as set forth at the time of grant. Awards generally vest annually over three or four years from the date of grant. The Company recognizes compensation costs for stock-based awards on a straight-line basis over the requisite service period (usually the vesting period) for each award. Share-based payments to employees, including grants of employee stock options, are recognized in the financial statements over the vesting period based on their grant date fair values. Authoritative guidance requires that compensation costs be recognized for unvested stock-based compensation awards over the period through the date that the employee is no longer required to provide future services to earn the award, rather than over the explicit service period. Accordingly, the Company follows a policy of recognizing compensation cost to coincide with the date that the employee is eligible to retire, rather than the actual retirement date, for all stock-based compensation granted.
Per share data	Basic earnings per ordinary share is based on weighted average ordinary shares outstanding and excludes any dilutive effects of options. Diluted earnings per ordinary share assumes the exercise of all dilutive stock options has occurred.
Recent accounting pronouncements	In August 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update concerning the evaluation of an entity's ability to continue as a going concern. Under this new guidance, in connection with preparing financial statements for each annual and interim reporting period, an entity's management should evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued. Management's evaluation should be based on relevant conditions and events that are known and reasonably knowable at the date that the financial statements are issued. Substantial doubt exists when it is probable that the entity will be unable to meet its obligations as they become due. When management identifies conditions or events that raise substantial doubt about an entity's ability to continue as a going concern, management should consider whether its plans that are intended to mitigate those conditions or events will alleviate the substantial doubt. The mitigating effect of management's plans should be considered only to the extent that it is probable that the plans will be implemented, and if implemented, it is probable that the plans will be effective. If conditions or events raise substantial doubt, the entity should disclose the conditions or events, management's evaluation of their significance in relation to the ability to meet its obligations, and management's plans to mitigate the conditions or events along with whether substantial doubt has been alleviated. The guidance is effective for annual periods ending after December 15, 2016, and interim and annual periods thereafter. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on its financial condition, results of operations or cash flows. In November 2014, the FASB issued an accounting standards update which provides an acquired entity with the option to reflect assets and liabilities using its acquirer's accounting and reporting basis ("pushdown accounting") within its own separate financial statements. Under this new guidance, an acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in control event occurs (on a case by case basis if multiple). If the entity elects to apply pushdown accounting, it should disclose information that enables users of the financial statements to evaluate the effect of pushdown accounting. If pushdown accounting is not applied in the initial reporting period, an acquired entity will have the option to elect to apply it in a subsequent reporting period, however, such an election should be considered a change in accounting principle. Once pushdown accounting is elected, that election is irrevocable. The guidance was effective upon issuance. Its adoption did not have an impact on the financial condition, results of operations or cash flows of the Company. In February 2015, the FASB issued an accounting standards update concerning consolidation of certain legal entities. Under this new guidance, all legal entities are required to evaluate whether they should consolidate certain legal entities. The guidance: (1) modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities; (2) eliminates the presumption that a general partner should consolidate a limited partnership; (3) affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships; and (4) provides a scope exception from consolidation guidance for certain reporting entities. Upon adoption of the new guidance, differing requirements for performing a consolidation analysis under existing GAAP will be eliminated, and all reporting entities will now fall within the scope of the Accounting Standards Codification Subtopic 810-10, Consolidation-Overall , unless a specific exception applies. Under this Subtopic, there are only two primary models for determining whether consolidation is appropriate - a voting interest entity model, and a variable interest entity model. The guidance is effective for public business entities for annual periods beginning after December 15, 2015, and interim and annual periods thereafter, with early adoption permitted. The Company is currently evaluating the impact of this guidance. In April 2015, the FASB issued an accounting standards update concerning the presentation of deferred debt issuance costs in an entity's balance sheet. Under this new guidance, which is part of the FASB's initiative to reduce complexity in accounting standards while maintaining or improving the usefulness of the information provided to users of financial statements, debt issuance costs related to a recognized debt liability must be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. In addition, the guidance also requires that the amortization of such costs be reported as interest expense. The guidance is effective for public business entities for annual periods beginning after December 15, 2015, and interim and annual periods thereafter, with early adoption permitted for financial statements that have not been previously issued. This guidance will not have a material impact on the Company's financial condition, results of operations or cash flows. In May 2015, the FASB issued an accounting standards update concerning investments for which management estimates fair value using net asset value per share (or its equivalent) as a practical expedient. Under the guidance, such investments will no longer be reported within the fair value hierarchy. Removing those investments from the fair value hierarchy not only eliminates the diversity in practice resulting from the way in which investments measured at net asset value per share (or its equivalent) with future redemption dates are classified, but also ensures that all investments categorized in the fair value hierarchy are classified using a consistent approach. Investments that calculate net asset value per share (or its equivalent), but for which the practical expedient is not applied, will continue to be included in the fair value hierarchy. A reporting entity should continue to disclose information on investments for which fair value is measured at net asset value (or its equivalent) as a practical expedient to help users understand the nature and risks of the investments and whether the investments, if sold, are probable of being sold at amounts different from net asset value. The guidance is effective for public business entities for annual periods beginning after December 15, 2015 and interim and annual periods thereafter, with early adoption permitted. The Company is currently evaluating the impact of this guidance, but as this guidance is disclosure-related only, it is not expected to have a material impact on the Company's financial condition, results of operations or cash flows. In May 2015, the FASB issued an accounting standards update concerning the annual disclosure regarding the liability for unpaid claims and claims adjustment expenses for insurance entities. The guidance requires: (1) incurred and paid claims development information by accident year, on a net basis after reinsurance, for the number of years for which claims incurred typically remain outstanding, including the most recent reporting period, which need not exceed 10 years; (2) a reconciliation of incurred and paid claims development information to the aggregate carrying amount of the liability for unpaid claims and claim adjustment expenses, with separate disclosure of reinsurance recoverable on unpaid claims for each period presented in the statement of financial position; (3) for each accident year for which incurred claims development information is presented, the total of incurred but not reported ("IBNR") liabilities plus expected development on reported claims included in the liability for unpaid claims and claims adjustment expenses, accompanied by a description of reserving methodologies; (4) for each accident year for which incurred claims development information is presented, quantitative information about claim frequency (unless it is impracticable to do so) accompanied by a qualitative description of methodologies used for determining claim frequency information; and (5) for all claims, the average annual percentage payout of incurred claims by age for the same number of accident years as the disclosure for IBNR. The guidance recommends that insurance entities aggregate or disaggregate those disclosures so that useful information is not obscured by either the inclusion of a large amount of insignificant detail or the aggregation of items that have significantly different characteristics. The amendments also require insurance entities to disclose information about significant changes in methodologies and assumptions used to calculate the liability for unpaid claims and claim adjustment expenses, including reasons for the change and the effects on the financial statements. Additionally, the amendments require insurance entities to disclose for annual and interim reporting periods a rollforward of the liability for unpaid claims and claims adjustment expenses. Additional disclosures about liabilities for unpaid claims and claim adjustment expenses reported at present value include: (1) for each period presented in the statement of financial position, the aggregate amount of discount for the time value of money deducted to derive the liability for unpaid claims and claim adjustment expenses; (2) for each period presented in the statement of income, the amount of interest accretion recognized; and (3) the line items in the statement of income in which interest accretion is classified. The guidance is effective for public business entities for annual periods beginning after December 15, 2015 and interim periods within annual periods after December 15, 2016. Early adoption is permitted. The Company is currently evaluating the impact of this guidance, but as this guidance is disclosure-related only, it is not expected to have a material impact on the Company's financial condition, results of operations or cash flows. In September 2015, the FASB issued an accounting standards update concerning the accounting for measurement period adjustments following the completion of a business combination. The measurement period ends as soon as the acquirer receives the information it was seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable; however, it shall not exceed one year from the acquisition date. Currently under GAAP, during the measurement period the acquirer shall recognize such adjustments to the provisional amounts as if the accounting for the business combination had been completed at the acquisition date, with a corresponding adjustment to goodwill, in the reporting period in which the adjustments are determined. The acquirer shall revise comparative information for prior periods presented in financial statements as needed as a result of the change to the provisional amounts calculated. Under the new guidance, although such adjustments shall still be calculated as if the accounting had been completed at the business combination date, the acquirer should recognize in its current-period earnings the cumulative effect of changes in depreciation, amortization, or other income effects, by line item, related to the periods subsequent to the acquisition date as a result of the adjustments. In addition, entities must present separately on the face of the income statement, or alternatively in the notes to the financial statements, the portion of such current period adjustments that would have been recorded in previous reporting periods, if the adjustments had been recognized at the acquisition date. The guidance is effective for provisional adjustments made by public business entities in annual periods beginning after December 15, 2015 - irrespective of the date of the business combination to which they relate - including interim periods within those fiscal years. Early adoption is permitted for financial statements that have not yet been made available for issuance. The Company has elected to early adopt this guidance in light of measurement period adjustments recognized as part of the Catlin Acquisition. The impacts of this guidance have been disclosed in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ." In January 2016, the FASB issued an accounting standards update concerning the accounting for financial instruments. The guidance retains the basic existing framework for accounting for financial instruments under GAAP, while achieving limited convergence with IFRS in this area. The guidance: (1) requires equity investments (except consolidated entities and those accounted for under the equity method of accounting) to be measured at fair value with changes in fair value recognized in net income; (2) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; (3) eliminates the requirement to disclose the fair value of financial instruments measured at amortized cost for non-public business entities; (4) eliminates the requirement to disclose the method(s) and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost on the balance sheet; (5) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (6) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial statements; (7) requires separate presentation of financial assets and financial liabilities by measurement category and form of asset in the financial statements; and (8) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity's other deferred tax assets. The guidance will be effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted at the beginning of the fiscal year of adoption only, and should be applied by means of a cumulative effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption, except the amendments related to impairment of equity securities without readily determinable fair values. The Company is currently evaluating the impact of this guidance, but it is expected to have an effect on results of operations as mark to market movements will prospectively impact net income. It is not expected to have a material impact on the Company's financial condition or cash flows.

Acquisitions and Disposals (Tab

Acquisitions and Disposals (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Calculation of the consideration transferred in acquisition	The calculation of the consideration transferred to acquire Catlin Shares is as follows: (In thousands, except per share data) Catlin Shares outstanding as of April 30, 2015 that received share consideration (including the dilutive effect of warrants) 384,118 Exchange ratio per the Implementation Agreement 0.130 XL Share issuance to Catlin shareholders 49,935 Closing price per XL share on April 30, 2015 (1) $ 37.08 XL Share issuance consideration $ 1,851,601 Catlin Shares outstanding as of April 30, 2015 that received cash consideration (including the dilutive effect of warrants) 384,118 Cash price component, per Catlin Share in GBP £ 3.88 Cash consideration, in GBP £ 1,490,377 Foreign exchange rate: GBP/USD on April 30, 2015 $ 1.5349 Cash consideration $ 2,287,579 Total acquisition consideration $ 4,139,180 ____________ (1) The closing market price of XL Shares on the Acquisition Date represents the fair value of XL shares issued as part of the Acquisition Consideration.
Schedule of assets acquired and liabilities assumed	The following table summarizes the fair values of the assets acquired and liabilities assumed at the Acquisition Date: (U.S. dollars in thousands) ASSETS Fixed maturities, at fair value $ 6,266,489 Short-term investments, at fair value 634,599 Equity investments, at fair value 236,230 Investment in affiliates 216,843 Other investments 386,828 Total investments $ 7,740,989 Cash and cash equivalents (1) 1,267,565 Accrued investment income 35,063 Premiums receivable 2,545,188 Unpaid losses and loss expenses recoverable 1,493,267 Reinsurance balances receivable 299,579 Ceded unearned premiums 1,143,852 Deferred acquisition costs and value of business acquired 679,259 Intangible assets 988,000 Receivable from investments sold 9,633 Other assets (2) 306,686 Total assets $ 16,509,081 LIABILITIES Unpaid losses and loss expenses $ 6,933,144 Unearned premiums 3,742,234 Reinsurance balances payable 1,441,749 Notes payable and debt 82,066 Payable for investments purchased 34,149 Deferred tax liability (2) 82,783 Other liabilities (2) 285,481 Total liabilities $ 12,601,606 Net assets acquired before non-controlling interest $ 3,907,475 Non-controlling interest in equity of consolidated subsidiaries 562,285 Net assets acquired $ 3,345,190 Acquisition consideration $ 4,139,180 Goodwill (2) $ 793,990 ____________ (1) Includes Restricted cash. (2) Includes an increase of $15.9 million to goodwill from the amount initially recorded at June 30, 2015, as a result of several tax-related adjustments, including a decrease in other assets of $7.5 million , a decrease in deferred tax liability of $11.3 million , and an increase in other liabilities of $19.8 million . See discussion of "Income Taxes" below for further information.
Schedule of restructuring costs	(U.S. dollars in thousands) Severance related costs Retention and other compensation costs Facilities-related costs Consulting and other Total Costs incurred in 2015 $ 47,185 $ 35,310 $ 14,744 $ 59,129 $ 156,368 2015 payments 31,058 18,341 13,926 35,754 99,079 Liabilities at December 31, 2015 $ 16,127 $ 16,969 $ 818 $ 23,375 $ 57,289
Results since acquisition	(U.S. dollars in thousands) May 1, 2015 to December 31, 2015 Total revenues - see comments above $ 2,791,789 Net income (loss) - see comments above $ 103,637
Pro Forma information	The following table presents unaudited pro forma consolidated information for the years ended December 31, 2015 and 2014 and assumes the Catlin Acquisition occurred on January 1, 2014. The pro forma financial information is presented for informational purposes only and does not necessarily reflect the results that would have occurred had the acquisition taken place on January 1, 2014, nor is it necessarily indicative of future results. Significant adjustments used to determine pro forma results include amortization of intangible assets and amortization of fair value adjustments discussed above, and the corresponding income tax effects. Non-recurring transaction related costs noted above have been included in the unaudited pro forma results for the year ended December 31, 2014 . Unaudited Pro Forma (In thousands, except per share data) 2015 2014 Total revenues $ 10,628,915 $ 10,938,216 Net income attributable to ordinary shareholders 1,221,497 475,914 Earnings (loss) per ordinary share and ordinary share equivalent – basic 4.03 1.50 Earnings (loss) per ordinary share and ordinary share equivalent – diluted 3.97 1.48
Impact of Life Retro Arrangements	The impact of the GreyCastle Life Retro Arrangements on the Company's results for the year ended December 31, 2015 and the period beginning from the completion of the transaction on May 30, 2014 through December 31, 2014 was as follows: Impact of GreyCastle Life Retro Arrangements May 30 to December 31, (U.S. dollars in thousands) 2015 2014 Underwriting profit (loss) (1) $ 605 $ 11,649 Net investment income - Life Funds Withheld Assets 187,489 129,575 Net realized gains (losses) on investments sold - Life Funds Withheld Assets 223,272 5,067 Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets (27,734 ) (9 ) OTTI on investments - Life Funds Withheld Assets (13,357 ) (20,587 ) Exchange (gains) losses 4,788 10,099 Other income and expenses 2,280 (1,610 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets (151,691 ) (488,222 ) Net income (loss) $ 225,652 $ (354,038 ) Change in net unrealized gains (losses) on investments - Life Funds Withheld Assets, net of tax (421,604 ) 274,083 Change in adjustments related to future policy benefit reserves, net of tax 170,688 74,009 Change in cumulative translation adjustment - Life Funds Withheld Assets, net of tax 25,869 17,595 Total changes to other comprehensive income as a result of GreyCastle Life Retro Arrangements (2) $ (225,047 ) $ 365,687 Comprehensive income (loss) $ 605 $ 11,649 ____________ (1) The underwriting profit of $0.6 million relates to a premium adjustment relating to the GreyCastle Life Retro Arrangements transaction, which was completed on May 30, 2014. Excluding this transaction, the impact to comprehensive income relating to the GreyCastle Life Retro Arrangements was nil for the years ended December 31, 2015 and 2014 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Summary of assets and liabilities that were accounted for at fair value	The following tables set forth the Company’s assets and liabilities that were accounted for at fair value at December 31, 2015 and 2014 by level within the fair value hierarchy. For further information, see Note 2(b), "Significant Accounting Policies - Fair Value Measurements ": December 31, 2015 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2015 Assets Fixed maturities - Available for Sale ("AFS") - Excluding Life Funds Withheld Assets U.S. Government and Government - Related/Supported $ — $ 5,020,574 $ 45,063 $ — $ 5,065,637 Corporate - Financials — 3,508,224 53,685 — 3,561,909 Corporate - Non Financials — 6,900,259 188 — 6,900,447 Residential mortgage-backed securities – Agency ("RMBS - Agency") — 3,754,894 3,077 — 3,757,971 Residential mortgage-backed securities – Non-Agency ("RMBS - Non-Agency") — 328,540 — — 328,540 Commercial mortgage-backed securities ("CMBS") — 405,316 — — 405,316 Collateralized debt obligations ("CDO") — 2 32,408 — 32,410 Other asset-backed securities — 1,150,715 17,857 — 1,168,572 U.S. States and political subdivisions of the States — 2,632,070 — — 2,632,070 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 5,251,614 — — 5,251,614 Total fixed maturities - AFS - Excluding Life Funds Withheld Assets, at fair value $ — $ 28,952,208 $ 152,278 $ — $ 29,104,486 Equity securities, at fair value 528,581 350,338 — — 878,919 Short-term investments, at fair value (1) — 617,390 — — 617,390 Total investments AFS - Excluding Life Funds Withheld Assets $ 528,581 $ 29,919,936 $ 152,278 $ — $ 30,600,795 Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government - Related/Supported — 12,742 — — 12,742 Corporate - Financials — 598,236 — — 598,236 Corporate - Non Financials — 1,308,628 — — 1,308,628 RMBS - Agency — 752 — — 752 RMBS - Non-Agency — 26,953 — — 26,953 CMBS — 122,481 — — 122,481 Other asset-backed securities — 149,795 — — 149,795 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 933,516 — — 933,516 Total fixed maturities - AFS - Life Funds Withheld Assets, at fair value — 3,153,103 — — 3,153,103 Total investments - AFS, at fair value 528,581 33,073,039 152,278 — 33,753,898 December 31, 2015 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2015 Fixed maturities - Trading U.S. Government and Government - Related/Supported — 4,990 — — 4,990 Corporate - Financials — 335,956 — — 335,956 Corporate - Non Financials — 493,621 — — 493,621 RMBS - Agency — 368 — — 368 CMBS — 4,803 — — 4,803 Other asset-backed securities — 25,700 — — 25,700 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 370,261 — — 370,261 Total fixed maturities - Trading, at fair value — 1,235,699 — — 1,235,699 Short-term investments, at fair value — 60,330 — — 60,330 Total investments Trading — 1,296,029 — — 1,296,029 Cash equivalents (2) 437,742 830,924 — — 1,268,666 Cash equivalents - Life Funds Withheld Assets 517 100,757 — — 101,274 Other investments (3) — 1,008,176 283,550 — 1,291,726 Other assets (4) — 69,914 19,400 (3,087 ) 86,227 Total assets accounted for at fair value $ 966,840 $ 36,378,839 $ 455,228 $ (3,087 ) $ 37,797,820 Liabilities Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) (5) $ — $ 463,915 $ — $ — $ 463,915 Financial instruments sold, but not yet purchased (6) 347 — — — 347 Other liabilities (4) — 16,304 29,191 (3,087 ) 42,408 Total liabilities accounted for at fair value $ 347 $ 480,219 $ 29,191 $ (3,087 ) $ 506,670 December 31, 2014 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2014 Assets Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ — $ 2,171,953 $ — $ — $ 2,171,953 Corporate - Financials — 2,761,916 — — $ 2,761,916 Corporate - Non Financials — 6,010,563 5,894 — $ 6,016,457 Residential mortgage-backed securities – RMBS - Agency — 3,726,666 1,910 — $ 3,728,576 Residential mortgage-backed securities – RMBS - Non-Agency — 427,351 — — $ 427,351 CMBS — 1,052,544 — — $ 1,052,544 CDOs — 4,076 687,958 — $ 692,034 Other asset-backed securities — 1,060,005 5,288 — $ 1,065,293 U.S. States and political subdivisions of the States — 2,021,272 — — $ 2,021,272 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 4,240,073 — — $ 4,240,073 Total fixed maturities - AFS - Excluding Funds Withheld Assets, at fair value $ — $ 23,476,419 $ 701,050 $ — $ 24,177,469 Equity securities, at fair value 502,284 366,008 — — 868,292 Short-term investments, at fair value (1) — 256,727 — — 256,727 Total investments AFS - Excluding Funds Withheld Assets $ 502,284 $ 24,099,154 $ 701,050 $ — $ 25,302,488 December 31, 2014 (U.S. dollars in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Collateral and Counterparty Netting Balance at December 31, 2014 Fixed maturities - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ — $ 18,724 $ — $ — $ 18,724 Corporate - Financials — 801,019 — — $ 801,019 Corporate - Non Financials — 2,016,961 — — $ 2,016,961 RMBS – Agency — 3,782 — — $ 3,782 RMBS – Non-Agency — 85,335 — — $ 85,335 CMBS — 193,167 — — $ 193,167 Other asset-backed securities — 273,541 — — $ 273,541 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported — 1,789,036 — — $ 1,789,036 Total fixed maturities - AFS - Life Funds Withheld Assets, at fair value $ — $ 5,181,565 $ — $ — $ 5,181,565 Total investments - AFS, at fair value $ 502,284 $ 29,280,719 $ 701,050 $ — $ 30,484,053 Fixed maturities - Trading Corporate - Non Financials — 1,171 — — $ 1,171 Total fixed maturities - Trading, at fair value $ — $ 1,171 $ — $ — $ 1,171 Cash equivalents (2) 1,103,877 397,955 — — $ 1,501,832 Cash equivalents - Life Funds Withheld Assets (2) 460 132,738 — — $ 133,198 Other investments (3) — 708,974 185,083 — $ 894,057 Other assets (4) — 122,996 13,663 (696 ) $ 135,963 Total assets accounted for at fair value $ 1,606,621 $ 30,644,553 $ 899,796 $ (696 ) $ 33,150,274 Liabilities Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) (5) $ — $ 450,831 $ — $ — $ 450,831 Financial instruments sold, but not yet purchased (6) 4,737 25,669 — — $ 30,406 Other liabilities (4) — 7,757 23,427 (696 ) $ 30,488 Total liabilities accounted for at fair value $ 4,737 $ 484,257 $ 23,427 $ (696 ) $ 511,725 ____________ (1) Short-term investments consist primarily of Corporate securities and U.S. and Non-U.S. Government and Government-Related/ Supported securities. (2) Cash equivalents balances subject to fair value measurement include certificates of deposit and money market funds. Operating cash balances are not subject to recurring fair value measurement guidance. (3) The Other investments balance excludes certain structured transactions including certain investments in project finance transactions, a payment obligation and liquidity financing provided to a structured credit vehicle as a part of a third party medium term note facility. These investments, which totaled $141.3 million at December 31, 2015 and $354.4 million at December 31, 2014 , are carried at amortized cost. For further information, see Note 8, "Other Investments ." (4) Other assets and other liabilities include derivative instruments. The derivative balances included in each category are reported on a gross basis by level with a netting adjustment presented separately in the Collateral and Counterparty Netting column. The fair values of the individual derivative contracts are reported gross in their respective levels based on the fair value hierarchy. For further details regarding derivative fair values and associated collateral received or paid see Note 15, "Derivative Instruments ." (5) Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) include balances related to the life retrocession embedded derivative, under which all investment results associated with the Life Funds Withheld Assets related the GreyCastle Life Retro Arrangements described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary ", accrue to the benefit of GCLR. (6) Financial instruments sold, but not yet purchased, represent "short sales" and are included within "Payable for investments purchased" on the balance sheets.
Additional information about assets and liabilities measured at fair value on a recurring basis - Level 3	Level 3 Assets and Liabilities - Year Ended December 31, 2015 (U.S. dollars in thousands) U.S. Government and Government - Related/Supported Corporate - Financials Corporate - Non-Financials RMBS - Agency Balance, beginning of period $ — $ — $ 5,894 $ 1,910 Realized gains (losses) — 9 (186 ) — Movement in unrealized gains (losses) — (10 ) (13 ) (3 ) Purchases and issuances (1) 35,044 53,686 (123 ) 1,297 Sales — — — — Settlements — — (316 ) (323 ) Transfers into Level 3 10,019 — — 3,059 Transfers out of Level 3 — — (5,068 ) (2,863 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ 45,063 $ 53,685 $ 188 $ 3,077 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ (2 ) $ (153 ) $ (2 ) RMBS - Non CMBS CDO Other asset- Balance, beginning of period $ — $ — $ 687,958 $ 5,288 Realized gains (losses) — — (8,658 ) 628 Movement in unrealized gains (losses) — — 16,688 (599 ) Purchases and issuances (1) — — 25,882 46,940 Sales — — (366,633 ) (7,269 ) Settlements — — (322,829 ) (6,359 ) Transfers into Level 3 — — — 13,317 Transfers out of Level 3 — — — (34,089 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 32,408 $ 17,857 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 5,279 $ 451 Non-US Sovereign Short-term Other investments Derivative Contracts Balance, beginning of period $ — $ — $ 185,083 $ (9,764 ) Realized gains (losses) — — 15,270 — Movement in unrealized gains (losses) — — (12,548 ) (27 ) Purchases and issuances (1) — — 117,143 — Sales — — (1,417 ) — Settlements — — (19,981 ) — Transfers into Level 3 — — — — Transfers out of Level 3 — — — — Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 283,550 $ (9,791 ) Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 2,724 $ 80 ____________ (1) Includes assets acquired as result of the transaction described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition " Level 3 Assets and Liabilities - Year Ended December 31, 2014 (U.S. dollars in thousands) U.S. Government and Government - Related/Supported Corporate - Financials Corporate - Non-Financials RMBS - Agency Balance, beginning of period $ — $ — $ 31,573 $ 10,473 Realized gains (losses) — — 199 5 Movement in unrealized gains (losses) — — (128 ) (18 ) Purchases and issuances — — 3,759 120 Sales — — — — Settlements — — (6,543 ) (3,205 ) Transfers into Level 3 — — 766 — Transfers out of Level 3 — — (23,732 ) (5,465 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 5,894 $ 1,910 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 60 $ (12 ) RMBS - Non Agency CMBS CDO Other asset- backed securities Balance, beginning of period $ 9 $ 12,533 $ 710,253 $ 11,877 Realized gains (losses) 1 3 3,781 (7 ) Movement in unrealized gains (losses) 1 (3 ) 11,604 65 Purchases and issuances — 1,376 185,710 5,182 Sales — — (48,313 ) — Settlements (11 ) (12,533 ) (175,077 ) (5,705 ) Transfers into Level 3 — — — — Transfers out of Level 3 — (1,376 ) — (6,124 ) Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 687,958 $ 5,288 Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 14,432 $ 57 Non-US Sovereign Government, Provincial, Supranational and Government Related/Supported Short-term investments Other investments Derivative Contracts - Net Balance, beginning of period $ — $ 2,015 $ 113,472 $ (29,110 ) Realized gains (losses) — — 12,676 — Movement in unrealized gains (losses) — (15 ) 538 19,346 Purchases and issuances — — 59,401 — Sales — — — — Settlements — (2,000 ) (25,498 ) — Transfers into Level 3 — — 24,494 — Transfers out of Level 3 — — — — Fixed maturities to short-term investments classification change — — — — Balance, end of period $ — $ — $ 185,083 $ (9,764 ) Movement in total gains (losses) above relating to instruments still held at the reporting date $ — $ — $ 13,212 $ 19,346
Financial instruments for which the carrying values differs from the estimated fair value	The following table includes financial instruments for which the carrying value differs from the estimated fair values at December 31, 2015 and 2014 . All of these fair value estimates are considered Level 2 fair value measurements. (U.S. dollars in thousands) 2015 2014 Carrying Value Fair Value Carrying Value Fair Value Financial Assets - Other investments, structured transactions $ 141,329 $ 154,065 $ 354,382 $ 371,625 Deposit liabilities $ 1,168,376 $ 1,436,210 $ 1,245,367 $ 1,543,761 Notes payable and debt 2,644,970 2,805,152 1,662,580 1,897,854 Financial Liabilities $ 3,813,346 $ 4,241,362 $ 2,907,947 $ 3,441,615

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Schedule of segment reporting, by segment	The following tables summarize the segment results for the indicated years ended: Year Ended December 31, 2015 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate and Other (1) Total Gross premiums written $ 8,395,846 $ 2,273,163 $ 10,669,009 $ 309,916 $ 10,978,925 Net premiums written 5,859,934 2,028,890 7,888,824 62,239 7,951,063 Net premiums earned 5,648,482 2,515,702 8,164,184 62,241 8,226,425 Net losses and loss expenses (2) 3,614,048 1,152,152 4,766,200 115,997 4,882,197 Acquisition costs (2) 704,364 602,290 1,306,654 10,794 1,317,448 Operating expenses (3) 1,154,760 283,379 1,438,139 1,232 1,439,371 Underwriting profit (loss) $ 175,310 $ 477,881 $ 653,191 $ (65,782 ) $ 587,409 Net investment income - excluding Life Funds Withheld Assets (4) 583,871 40,569 624,440 Net investment income - Life Funds Withheld Assets 187,489 187,489 Net results from structured products (5) 12,185 5,806 17,991 — 17,991 Net fee income and other (6) (16,936 ) 2,958 (13,978 ) 622 (13,356 ) Extinguishment of debt — 5,592 5,592 Net realized gains (losses) on investments - excluding Life Funds Withheld Assets 14,586 5,411 19,997 Net realized gains (losses) on investments and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets — 182,181 182,181 Net realized and unrealized gains (losses) on derivative instruments — 53,123 53,123 Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets — (151,691 ) (151,691 ) Net income (loss) from investment fund affiliates and operating affiliates — 118,060 118,060 Gain on sale of operating affiliate 340,407 340,407 Exchange (gains) losses — 22,504 22,504 Corporate operating expenses — 480,755 480,755 Contribution from P&C and Corporate and Other 1,255,661 201,538 1,457,199 Interest expense (7) 163,021 163,021 Non-controlling interests 106,187 106,187 Income tax expense (19,161 ) (19,161 ) Net income (loss) attributable to ordinary shareholders $ 1,207,152 Ratios – P&C operations: (8) Loss and loss expense ratio 64.0 % 45.8 % 58.4 % Underwriting expense ratio 32.9 % 35.2 % 33.6 % Combined ratio 96.9 % 81.0 % 92.0 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) The Company has reflected the amortization of certain fair value adjustments recorded in conjunction with the Catlin Acquisition within the respective segments. (3) Operating expenses of the segments exclude Corporate operating expenses, shown separately. (4) Net investment income - excluding Life Funds Withheld Assets does not include net investment income related to the net results from structured products. (5) The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million , respectively. (6) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (7) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (8) Ratios are based on net premiums earned from P&C operations. Year Ended December 31, 2014 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate & Other (1) Total Gross premiums written $ 5,976,011 $ 1,785,479 $ 7,761,490 $ 333,436 $ 8,094,926 Net premiums written 4,134,151 1,633,058 5,767,209 177,632 5,944,841 Net premiums earned 4,026,713 1,690,725 5,717,438 177,632 5,895,070 Net losses and loss expenses 2,543,108 715,285 3,258,393 242,963 3,501,356 Acquisition costs 393,319 330,684 724,003 14,115 738,118 Operating expenses (2) 865,592 193,404 1,058,996 10,693 1,069,689 Underwriting profit (loss) $ 224,694 $ 451,352 $ 676,046 $ (90,139 ) $ 585,907 Net investment income - excluding Life Funds Withheld Assets (3) 574,458 146,558 721,016 Net investment income - Life Funds Withheld Assets 129,575 129,575 Net results from structured products (4) 43,710 10,499 54,209 — 54,209 Net fee income and other (5) (10,051 ) 2,800 (7,251 ) 360 (6,891 ) Loss on sale of life reinsurance subsidiary — 666,423 666,423 Net realized gains (losses) on investments 119,366 3,625 122,991 Net realized gains (losses) on investments - Life Funds Withheld Assets — (15,529 ) (15,529 ) 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 ) Net income (loss) from investment fund affiliates and operating affiliates — 203,034 203,034 Exchange (gains) losses — (37,568 ) (37,568 ) Corporate operating expenses — 220,165 220,165 Contribution from P&C and Corporate and Other 1,416,828 (929,872 ) 486,956 Interest expense (6) 121,221 121,221 Non-controlling interests 80,498 80,498 Income tax expense 96,897 96,897 Net income (loss) attributable to ordinary shareholders $ 188,340 Ratios – P&C operations: (7) Loss and loss expense ratio 63.2 % 42.3 % 57.0 % Underwriting expense ratio 31.2 % 31.0 % 31.2 % Combined ratio 94.4 % 73.3 % 88.2 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) Operating expenses of the segments exclude Corporate operating expenses, shown separately. (3) Net investment income does not include net investment income related to the net results from structured products. (4) The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million , respectively. (5) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (6) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (7) Ratios are based on net premiums earned from P&C operations. Year Ended December 31, 2013 (U.S. dollars in thousands, except ratios) Insurance Reinsurance Total P&C Corporate and Other (1) Total Gross premiums written $ 5,523,181 $ 1,893,611 $ 7,416,792 $ 324,343 $ 7,741,135 Net premiums written 4,154,093 1,749,889 5,903,982 295,422 6,199,404 Net premiums earned 4,267,677 1,746,422 6,014,099 295,422 6,309,521 Net losses and loss expenses 2,829,999 901,465 3,731,464 465,702 4,197,166 Acquisition costs 529,270 353,388 882,658 26,665 909,323 Operating expenses (2) 782,677 166,238 948,915 8,926 957,841 Underwriting profit (loss) $ 125,731 $ 325,331 $ 451,062 $ (205,871 ) $ 245,191 Net investment income (3) 599,144 286,645 885,789 Net results from structured products (4) 15,562 8,229 23,791 — 23,791 Net fee income and other (5) (9,317 ) 2,320 (6,997 ) 1,305 (5,692 ) Net realized gains (losses) on investments 85,792 1,985 87,777 Net realized and unrealized gains (losses) on derivative instruments — 7,798 7,798 Net income (loss) from investment fund affiliates and operating affiliates — 258,195 258,195 Exchange (gains) losses — (28,243 ) (28,243 ) Corporate operating expenses — 209,454 209,454 Contribution from P&C and Corporate and Other 1,152,792 168,846 1,321,638 Interest expense (6) 107,486 107,486 Non-controlling interests 76,731 76,731 Income tax expense 77,505 77,505 Net income (loss) attributable to ordinary shareholders $ 1,059,916 Ratios – P&C operations: (7) Loss and loss expense ratio 66.3 % 51.6 % 62.0 % Underwriting expense ratio 30.8 % 29.8 % 30.5 % Combined ratio 97.1 % 81.4 % 92.5 % ____________ (1) Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations. (2) Operating expenses exclude Corporate operating expenses, shown separately. (3) Net investment income does not include net investment income related to the net results from structured products. (4) The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million , respectively. (5) Net fee income and other includes operating expenses from the Company's loss prevention consulting services business. (6) Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments. (7) Ratios are based on net premiums earned from P&C operations.
Schedule of net premiums earned by line of business	The following tables summarize the Company’s net premiums earned by line of business: Year Ended December 31, 2015 (U.S. dollars in thousands) Insurance Reinsurance Corporate and Other Total P&C Operations: Professional $ 1,163,302 $ 168,367 $ — $ 1,331,669 Casualty 1,685,748 468,286 — 2,154,034 Property catastrophe — 663,958 — 663,958 Property 1,021,037 869,286 — 1,890,323 Specialty 1,473,929 127,797 — 1,601,726 Other (1) 304,466 218,008 — 522,474 Total P&C Operations $ 5,648,482 $ 2,515,702 $ — $ 8,164,184 Corporate and Other: Run-off life operations - Annuity — — 1 1 Run-off life operations - Other life — — 62,240 62,240 Total Corporate and Other $ — $ — $ 62,241 $ 62,241 Total $ 5,648,482 $ 2,515,702 $ 62,241 $ 8,226,425 Year Ended December 31, 2014 P&C Operations: Professional $ 1,075,420 $ 181,223 $ — $ 1,256,643 Casualty 1,422,684 300,223 — 1,722,907 Property catastrophe — 433,602 — 433,602 Property 544,856 555,583 — 1,100,439 Specialty 737,281 95,745 — 833,026 Other (1) 246,472 124,349 — 370,821 Total P&C Operations $ 4,026,713 $ 1,690,725 $ — $ 5,717,438 Corporate and Other: Run-off life operations - Annuity $ — $ — $ 53,363 $ 53,363 Run-off life operations - Other life — — 124,269 124,269 Total Corporate and Other $ — $ — $ 177,632 $ 177,632 Total $ 4,026,713 $ 1,690,725 $ 177,632 $ 5,895,070 Year Ended December 31, 2013 P&C Operations: Professional $ 1,370,196 $ 206,169 $ — $ 1,576,365 Casualty 1,389,851 312,156 — 1,702,007 Property catastrophe — 492,568 — 492,568 Property 544,278 561,105 — 1,105,383 Specialty 732,042 94,797 — 826,839 Other (1) 231,310 79,627 — 310,937 Total P&C Operations $ 4,267,677 $ 1,746,422 $ — $ 6,014,099 Corporate and Other: Run-off life operations - Annuity $ — $ — $ 122,715 $ 122,715 Run-off life operations - Other life — — 172,707 172,707 Total Corporate and Other $ — $ — $ 295,422 $ 295,422 Total $ 4,267,677 $ 1,746,422 $ 295,422 $ 6,309,521 ____________ (1) Other within the Insurance segment includes: excess and surplus, programs, surety, structured indemnity and certain discontinued lines. Other within the Reinsurance segment includes: whole account contracts, accident and health and other lines.
Schedule of net premiums written by geographic location	The following table shows an analysis of the Company’s net premiums written by geographical location of subsidiary where the premium is written for the years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 P&C Operations: Bermuda $ 781,618 $ 636,109 $ 658,041 United States 3,045,031 2,528,196 2,650,916 Europe 3,628,258 2,124,117 2,111,065 Other 433,917 478,787 483,960 Total P&C Operations $ 7,888,824 $ 5,767,209 $ 5,903,982 Corporate and Other: Bermuda $ 62,276 $ 91,979 $ 117,948 Europe (37 ) 85,653 177,474 Total Corporate and Other $ 62,239 $ 177,632 $ 295,422

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Amortized cost and fair value summary - AFS	The cost (amortized cost for fixed maturities and short-term investments), fair value, gross unrealized gains and gross unrealized (losses), including non-credit related OTTI recorded in accumulated other comprehensive income ("AOCI") of the Company’s AFS investments at December 31, 2015 and 2014 were as follows: Included in AOCI December 31, 2015 (U.S. dollars in thousands) Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Non-credit Related OTTI (1) Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 5,047,621 $ 52,355 $ (34,339 ) $ 5,065,637 $ — Corporate - Financials 3,535,830 49,535 (23,456 ) 3,561,909 — Corporate - Non Financials 6,867,525 130,568 (97,646 ) 6,900,447 — RMBS – Agency 3,697,756 77,776 (17,561 ) 3,757,971 — RMBS – Non-Agency 319,876 25,644 (16,980 ) 328,540 (54,200 ) CMBS 401,713 7,933 (4,330 ) 405,316 (1,182 ) CDO 41,679 4 (9,273 ) 32,410 (1,208 ) Other asset-backed securities 1,164,426 17,665 (13,519 ) 1,168,572 (1,144 ) U.S. States and political subdivisions of the States 2,514,048 125,395 (7,373 ) 2,632,070 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 5,249,148 100,383 (97,917 ) 5,251,614 — Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 28,839,622 $ 587,258 $ (322,394 ) $ 29,104,486 $ (57,734 ) Total short-term investments - Excluding Life Funds Withheld Assets 618,851 967 (2,428 ) 617,390 — Total equity securities 834,079 89,993 (45,153 ) 878,919 — Total investments - AFS - Excluding Life Funds Withheld Assets $ 30,292,552 $ 678,218 $ (369,975 ) $ 30,600,795 $ (57,734 ) Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 10,721 $ 2,021 $ — $ 12,742 $ — Corporate - Financials 531,016 67,220 — 598,236 — Corporate - Non Financials 1,132,926 175,702 — 1,308,628 — RMBS – Agency 591 161 — 752 — RMBS – Non-Agency 24,401 2,552 — 26,953 — CMBS 107,968 14,513 — 122,481 — Other asset-backed securities 132,674 17,121 — 149,795 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 737,735 195,781 — 933,516 — Total fixed maturities - AFS - Life Funds Withheld Assets $ 2,678,032 $ 475,071 $ — $ 3,153,103 $ — Total investments - AFS $ 32,970,584 $ 1,153,289 $ (369,975 ) $ 33,753,898 $ (57,734 ) ____________ (1) Represents the non-credit component of OTTI losses, adjusted for subsequent sales of securities. It does not include the change in fair value subsequent to the impairment measurement date. December 31, 2014 (U.S. dollars in thousands) Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Non-credit Related OTTI (1) Fixed maturities - AFS - Excluding Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 2,100,851 $ 77,889 $ (6,787 ) $ 2,171,953 $ — Corporate - Financials 2,687,797 87,058 (12,939 ) 2,761,916 — Corporate - Non Financials 5,774,333 278,747 (36,623 ) 6,016,457 (3,309 ) RMBS – Agency 3,625,171 114,188 (10,783 ) 3,728,576 — RMBS – Non-Agency 404,398 41,108 (18,155 ) 427,351 (67,918 ) CMBS 1,033,819 23,987 (5,262 ) 1,052,544 (2,033 ) CDOs 717,544 1,659 (27,169 ) 692,034 (1,663 ) Other asset-backed securities 1,028,528 42,810 (6,045 ) 1,065,293 (1,797 ) U.S. States and political subdivisions of the States 1,892,566 129,910 (1,204 ) 2,021,272 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 4,162,425 139,484 (61,836 ) 4,240,073 — Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 23,427,432 $ 936,840 $ (186,803 ) $ 24,177,469 $ (76,720 ) Total short-term investments - Excluding Life Funds Withheld Assets $ 257,221 $ 49 $ (543 ) $ 256,727 $ — Total equity securities - Excluding Life Funds Withheld Assets $ 763,833 $ 130,689 $ (26,230 ) $ 868,292 $ — Total investments - AFS - Excluding Life Funds Withheld Assets $ 24,448,486 $ 1,067,578 $ (213,576 ) $ 25,302,488 $ (76,720 ) Fixed maturities - AFS - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 14,866 $ 3,858 $ — $ 18,724 $ — Corporate - Financials 701,587 99,432 — 801,019 — Corporate - Non Financials 1,706,262 310,699 — 2,016,961 — RMBS – Agency 3,301 481 — 3,782 — RMBS – Non-Agency 71,075 14,260 — 85,335 — CMBS 168,886 24,281 — 193,167 — Other asset-backed securities 238,168 35,373 — 273,541 — Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 1,397,194 391,842 — 1,789,036 — Total fixed maturities - AFS - Life Funds Withheld Assets $ 4,301,339 $ 880,226 $ — $ 5,181,565 $ — Total investments - AFS $ 28,749,825 $ 1,947,804 $ (213,576 ) $ 30,484,053 $ (76,720 ) ____________ (1) Represents the non-credit component of OTTI losses, adjusted for subsequent sales of securities. It does not include the change in fair value subsequent to the impairment measurement date.
Amortized cost and fair value summary - Trading	The cost (amortized cost for fixed maturities and short-term investments) and fair value of the Company’s Trading investments at December 31, 2015 and 2014 were as follows: December 31, 2015 (U.S. dollars in thousands) Amortized Fair Value Fixed maturities - Trading - Life Funds Withheld Assets U.S. Government and Government-Related/Supported $ 4,957 $ 4,990 Corporate - Financials 344,070 335,956 Corporate - Non Financials 509,441 493,621 RMBS – Agency 370 368 CMBS 4,874 4,803 Other asset-backed securities 26,405 25,700 Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 373,492 370,261 Total fixed maturities - Trading - Life Funds Withheld Assets $ 1,263,609 $ 1,235,699 Total short-term investments - Trading - Life Funds Withheld Assets $ 60,176 $ 60,330 Total investments - Trading - Life Funds Withheld Assets $ 1,323,785 $ 1,296,029 December 31, 2014 (U.S. dollars in thousands) Amortized Fair Value Fixed maturities - Trading - Life Funds Withheld Assets Corporate - Non Financials $ 1,180 $ 1,171 Total investments - Trading - Life Funds Withheld Assets $ 1,180 $ 1,171
Contractual maturities summary	The contractual maturities of AFS and Trading fixed income securities at December 31, 2015 and 2014 are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (U.S. dollars in thousands) December 31, 2015 December 31, 2014 Amortized Cost Fair Value Amortized Cost Fair Value Fixed maturities - AFS - Excluding Life Funds Withheld Assets Due less than one year $ 2,106,851 $ 2,104,106 $ 1,972,224 $ 1,980,429 Due after 1 through 5 years 14,051,494 14,143,461 8,919,037 9,113,651 Due after 5 through 10 years 5,680,830 5,740,954 4,232,396 4,412,569 Due after 10 years 1,374,997 1,423,156 1,494,315 1,705,022 $ 23,214,172 $ 23,411,677 $ 16,617,972 $ 17,211,671 RMBS – Agency $ 3,697,756 $ 3,757,971 $ 3,625,171 $ 3,728,576 RMBS – Non-Agency 319,876 328,540 404,398 427,351 CMBS 401,713 405,316 1,033,819 1,052,544 CDO 41,679 32,410 717,544 692,034 Other asset-backed securities 1,164,426 1,168,572 1,028,528 1,065,293 Total mortgage and asset-backed securities $ 5,625,450 $ 5,692,809 $ 6,809,460 $ 6,965,798 Total fixed maturities - AFS - Excluding Life Funds Withheld Assets $ 28,839,622 $ 29,104,486 $ 23,427,432 $ 24,177,469 Fixed maturities - AFS - Life Funds Withheld Assets Due less than one year $ 81,700 $ 92,921 $ 117,048 $ 125,326 Due after 1 through 5 years 386,810 416,743 638,526 685,787 Due after 5 through 10 years 491,621 558,805 1,004,698 1,165,348 Due after 10 years 1,452,267 1,784,653 2,059,637 2,649,279 $ 2,412,398 $ 2,853,122 $ 3,819,909 $ 4,625,740 RMBS – Agency $ 591 $ 752 $ 3,301 $ 3,782 RMBS – Non-Agency 24,401 26,953 71,075 85,335 CMBS 107,968 122,481 168,886 193,167 Other asset-backed securities 132,674 149,795 238,168 273,541 Total mortgage and asset-backed securities $ 265,634 $ 299,981 $ 481,430 $ 555,825 Total fixed maturities - AFS - Life Funds Withheld Assets $ 2,678,032 $ 3,153,103 $ 4,301,339 $ 5,181,565 Total fixed maturities - AFS $ 31,517,654 $ 32,257,589 $ 27,728,771 $ 29,359,034 (U.S. dollars in thousands) December 31, 2015 December 31, 2014 Amortized Cost Fair Value Amortized Cost Fair Value Fixed maturities - Trading - Life Funds Withheld Assets Due less than one year $ 4,573 $ 5,096 $ — $ — Due after 1 through 5 years 278,163 272,220 — — Due after 5 through 10 years 280,487 277,920 1,180 1,171 Due after 10 years 668,737 649,592 — — $ 1,231,960 $ 1,204,828 $ 1,180 $ 1,171 RMBS – Agency 370 368 — — CMBS 4,874 4,803 — — Other asset-backed securities 26,405 25,700 — — Total mortgage and asset-backed securities 31,649 30,871 — — Total fixed maturities - Trading - Life Funds Withheld Assets $ 1,263,609 $ 1,235,699 $ 1,180 $ 1,171
Gross unrealized losses	The following is an analysis of how long the AFS securities at December 31, 2015 and 2014 had been in a continual unrealized loss position: December 31, 2015 (U.S. dollars in thousands) Less than 12 months Equal to or greater than 12 months Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities and short-term investments - AFS U.S. Government and Government-Related/Supported $ 3,762,869 $ (29,339 ) $ 89,113 $ (5,044 ) Corporate - Financials 1,641,021 (13,280 ) 102,022 (10,192 ) Corporate - Non Financials 3,275,270 (73,069 ) 227,527 (24,706 ) RMBS – Agency 1,065,055 (10,046 ) 221,211 (7,515 ) RMBS – Non-Agency 19,614 (1,104 ) 180,146 (15,876 ) CMBS 118,605 (1,561 ) 78,651 (2,769 ) CDO 12,311 (516 ) 20,096 (8,757 ) Other asset-backed securities 572,671 (5,252 ) 57,563 (8,268 ) U.S. States and political subdivisions of the States 565,055 (6,609 ) 12,259 (765 ) Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 1,921,286 (53,440 ) 474,929 (46,714 ) Total fixed maturities and short-term investments - AFS $ 12,953,757 $ (194,216 ) $ 1,463,517 $ (130,606 ) Total equity securities $ 356,742 $ (45,153 ) $ — $ — Less than 12 months Equal to or greater than 12 months December 31, 2014 (U.S. dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Fixed maturities and short-term investments - AFS U.S. Government and Government-Related/Supported $ 251,091 $ (1,196 ) $ 342,890 $ (5,603 ) Corporate – Financials 387,619 (5,858 ) 105,155 (7,097 ) Corporate – Non Financials 949,851 (28,023 ) 319,066 (8,657 ) RMBS – Agency 134,535 (220 ) 512,652 (10,563 ) RMBS – Non-Agency 45,378 (1,358 ) 202,700 (16,797 ) CMBS 78,356 (385 ) 169,065 (4,877 ) CDOs 249,803 (2,666 ) 414,516 (24,503 ) Other asset-backed securities 143,044 (2,813 ) 57,544 (3,232 ) U.S. States and political subdivisions of the States 32,187 (210 ) 63,695 (994 ) Non-U.S. Sovereign Government, Provincial, Supranational and Government-Related/Supported 624,346 (19,043 ) 558,422 (43,251 ) Total fixed maturities and short-term investments - AFS $ 2,896,210 $ (61,772 ) $ 2,745,705 $ (125,574 ) Total equity securities $ 191,193 $ (26,230 ) $ — $ —
Net investment income	Net investment income for the years ended December 31 is derived from the following sources: (U.S. dollars in thousands) 2015 2014 2013 Fixed maturities, short term investments and cash equivalents - Excluding Life Funds Withheld Assets $ 726,161 $ 809,964 $ 982,275 Fixed maturities, short term investments and cash equivalents - Life Funds Withheld Assets 187,489 129,575 — Equity securities and other investments 28,200 42,252 35,388 Interest on funds withheld 10,835 14,583 12,783 Total gross investment income $ 952,685 $ 996,374 $ 1,030,446 Investment expenses (80,315 ) (77,749 ) (72,730 ) Total net investment income $ 872,370 $ 918,625 $ 957,716
Net realized gains (losses)	The following represents an analysis of net realized gains (losses), the change in unrealized gains (losses) on investments and net realized and unrealized gains (losses) on investment related derivative instruments for the years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Fixed maturities, short term investments, cash and cash equivalents - Excluding Life Funds Withheld Assets: Gross realized gains $ 187,523 $ 119,817 $ 129,479 Gross realized losses on investments sold (134,441 ) (66,892 ) (84,703 ) OTTI on investments, net of amounts transferred to other comprehensive income (54,346 ) (12,341 ) (16,282 ) Net realized gains (losses) $ (1,264 ) $ 40,584 $ 28,494 Equity securities: Gross realized gains $ 79,556 $ 96,260 $ 29,402 Gross realized losses on investments sold (49,223 ) (12,270 ) (3,185 ) OTTI on investments, net of amounts transferred to other comprehensive income (15,954 ) (10,944 ) (17 ) Net realized gains (losses) $ 14,379 $ 73,046 $ 26,200 Other investments: Gross realized gains $ 39,198 $ 31,830 $ 46,934 Gross realized losses on investments sold (19,656 ) (10,011 ) (13,851 ) OTTI on investments, net of amounts transferred to other comprehensive income (12,660 ) (12,458 ) — Net realized gains (losses) $ 6,882 $ 9,361 $ 33,083 Net realized gains (losses) on investments - Excluding Life Funds Withheld Assets $ 19,997 $ 122,991 $ 87,777 Fixed maturities, short term investments, cash and cash equivalents - Life Funds Withheld Assets: Gross realized gains $ 259,798 $ 7,926 $ — Gross realized losses on investments sold (36,526 ) (2,859 ) — Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets (27,734 ) (9 ) — OTTI on investments, net of amounts transferred to other comprehensive income (13,357 ) (20,587 ) — Net realized gains (losses) on investments - Life Funds Withheld Assets $ 182,181 $ (15,529 ) $ — Net realized gains (losses) on investments $ 202,178 $ 107,462 $ 87,777 Net realized and unrealized gains (losses) on investment related derivative instruments $ (8,616 ) $ 20,121 $ 6,367 Net realized gains (losses) on investments and net realized and unrealized gains (losses) on investment related derivative instruments $ 193,562 $ 127,583 $ 94,144 Change in unrealized gains (losses): Fixed maturities – AFS - Excluding Life Funds Withheld Assets $ (486,140 ) $ 360,463 $ (913,174 ) Fixed maturities - AFS - Life Funds Withheld Assets (405,155 ) 880,226 — Fixed maturities – HTM — (272,540 ) (175,817 ) Equity securities (59,619 ) (32,577 ) 105,163 Affiliates and other investments (6,072 ) 35,143 26,636 Net change in unrealized gains (losses) on investments $ (956,986 ) $ 970,715 $ (957,192 ) Total net realized gains (losses) on investments, net realized and unrealized gains (losses) on investment related derivative instruments, and net change in unrealized gains (losses) on investments $ (763,424 ) $ 1,098,298 $ (863,048 )
Credit loss impairments	The following table sets forth the amount of credit loss impairments on fixed income securities, for which a portion of the OTTI loss was recognized in OCI, held by the Company as of the dates or for the periods indicated and the corresponding changes in such amounts. Credit Loss Impairments (U.S. dollars in thousands) 2015 2014 Opening balance at beginning of indicated period $ 131,942 $ 174,805 Credit loss impairment recognized in the current period on securities not previously impaired 9,698 3,907 Credit loss impairments previously recognized on securities which matured, paid down, prepaid or were sold during the period (54,648 ) (42,671 ) Credit loss impairments previously recognized on securities impaired to fair value during the period (2,629 ) — Additional credit loss impairments recognized in the current period on securities previously impaired 2,230 4,185 Accretion of credit loss impairments previously recognized due to an increase in cash flows expected to be collected (13,124 ) (8,284 ) Closing balance at end of indicated period $ 73,469 $ 131,942

Investments in Affiliates (Tabl

Investments in Affiliates (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	Investments in affiliates comprised the following at December 31, 2015 and 2014 . See Note 2(c), "Significant Accounting Policies - Total Investments - Investments in Affiliates," for a description of our accounting policy for these assets: (U.S. dollars in thousands) 2015 2014 Investment fund affiliates $ 1,386,837 $ 1,219,138 Operating affiliates 322,062 418,482 Total investment affiliates $ 1,708,899 $ 1,637,620
Investment fund affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	The Company’s equity investment in investment fund affiliates and equity in net income (loss) from such affiliates as well as certain summarized financial information of the investee on a combined basis (shown as "Combined Funds") are included below: Year Ended December 31, 2015 (U.S. dollars in thousands, except percentages) XL Group Investment Combined Carrying Equity in Weighted Total Net Assets Hedge Funds: Arbitrage $ 190,016 $ 612 8.6 % $ 2,202,112 Directional 551,262 31,012 7.2 % 7,643,134 Event Driven (2) 285,823 5,592 3.0 % 9,460,387 Multi-Style 57,097 5,452 3.6 % 1,600,959 Total hedge funds $ 1,084,198 $ 42,668 5.2 % $ 20,906,592 Private Investment Funds: 302,639 30,652 9.5 % 3,195,204 Total Investment Fund Affiliates $ 1,386,837 $ 73,320 5.8 % $ 24,101,796 Year Ended December 31, 2014 Hedge Funds: Arbitrage $ 134,400 $ 12,060 11.0 % $ 1,224,526 Directional 536,470 32,196 9.2 % 5,865,247 Event Driven (2) 300,168 21,030 3.1 % 9,703,973 Multi-Style 52,122 1,751 4.1 % 1,278,410 Total hedge funds $ 1,023,160 $ 67,037 5.7 % $ 18,072,156 Private Investment Funds: 195,978 28,779 17.7 % 1,105,776 Total Investment Fund Affiliates $ 1,219,138 $ 95,816 6.4 % $ 19,177,932 ____________ (1) Total estimated net assets are generally as at November 30 for hedge fund affiliates and September 30 for private investment fund affiliates. (2) The Company accounts for its investment in certain funds where the ownership percentage is less than three percent using the equity method, where the Company has significant influence over the related investment management company.
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	The Company’s equity investment in operating affiliates and equity in net income (loss) from such affiliates as well as certain summarized financial information of the investee as a whole are included below: Year ended December 31, 2015 (U.S. dollars in thousands) XL Group Investment Combined Investee Summarized Carrying Equity in Total Total Total Net Income Strategic and other operating affiliates $ 251,348 $ 33,608 $ 4,280,976 $ 3,293,873 $ 847,131 $ 91,701 Investment manager affiliates (1) 70,714 11,132 708,605 95,826 206,672 90,491 Total operating affiliates $ 322,062 $ 44,740 $ 4,989,581 $ 3,389,699 $ 1,053,803 $ 182,192 Year ended December 31, 2014 Strategic and other operating affiliates 317,216 50,132 4,679,395 3,691,173 1,075,935 152,122 Investment manager affiliates (1) 101,266 57,086 850,666 101,088 579,524 476,841 Total operating affiliates $ 418,482 $ 107,218 $ 5,530,061 $ 3,792,261 $ 1,655,459 $ 628,963 ____________ (1) During the years ended December 31, 2015 and 2014 , the Company received distributions from its Investment Manager Affiliates of approximately $25.3 million and $60.3 million , respectively. (2) Total assets and total liabilities reflect balances related to investees still held at December 31, 2015 and 2014 , respectively. Total revenue (loss) and net income (loss) reflect activity for the years ended December 31, 2015 and 2014 related to both investees still held at year-end and investees disposed of during the year.

Other Investments (Tables)

Other Investments (Tables)	12 Months Ended
	Dec. 31, 2015
Investments, All Other Investments [Abstract]
Components of other investments	Other investments comprised the following at December 31, 2015 and 2014 . See Note 2(c), "Significant Accounting Policies - Total Investments - Other Investments," for a description of our accounting policy for these assets: Year ended December 31, (U.S. dollars in thousands) 2015 2014 Hedge Funds: Arbitrage $ 205,117 $ 179,821 Directional 276,277 336,082 Event Driven 5,427 56,238 Multi-Style 57,249 68,706 Total hedge funds $ 544,070 $ 640,847 Private investment funds 244,576 129,243 Overseas deposits 479,187 92,223 Structured transactions 138,608 350,563 Other 26,616 35,563 Total other investments $ 1,433,057 $ 1,248,439
Analysis of net realized and unrealized gains	The following represents an analysis of the net realized gains for the indicated years ended December 31, and the net unrealized gains as of December 31, on the Company’s hedge funds and private investment funds: Year ended December 31, (U.S. dollars in thousands) Net Unrealized Gains Net Realized Gains (Losses) 2015 2014 2015 2014 2013 Hedge funds $ 188,698 $ 188,674 $ 12,769 $ 6,685 $ 30,858 Private investment funds 38,340 42,604 9,342 13,275 4,331 Total $ 227,038 $ 231,278 $ 22,111 $ 19,960 $ 35,189

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill & intangible assets	The following table presents an analysis of intangible assets broken down between goodwill, intangible assets with an indefinite life and intangible assets with a definite life for the years ended December 31, 2015, 2014 and 2013 : (U.S. dollars in thousands) Goodwill Intangible assets with an indefinite life Intangible assets with a definite life Total Balance at December 31, 2012 $ 392,882 $ 15,366 $ 279 $ 408,527 Amortization — — (279 ) (279 ) Foreign currency translation 3,363 — — 3,363 Balance at December 31, 2013 $ 396,245 $ 15,366 $ — $ 411,611 Additions 25,159 — 18,500 43,659 Amortization — — (1,850 ) (1,850 ) Foreign currency translation (5,468 ) — — (5,468 ) Balance at December 31, 2014 $ 415,936 $ 15,366 $ 16,650 $ 447,952 Additions 807,381 673,000 315,000 1,795,381 Amortization — — (15,517 ) (15,517 ) Foreign currency translation (9,687 ) (5,507 ) (2,356 ) (17,550 ) Balance at December 31, 2015 $ 1,213,630 $ 682,859 $ 313,777 $ 2,210,266
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Future amortization expenses are expected to be as follows: Year Ended December 31, 2016 $ 22,350 2017 19,017 2018 17,350 2019 17,350 2020 17,350 2021-2036 220,360 Total expected amortization expenses $ 313,777
Schedule Of Acquired Intangible Assets By Major Class [Table Text Block]	The following table summarizes the intangible assets and their related useful lives recorded in connection with the Catlin Acquisition, as described in Note 3(c), "Acquisitions and Disposals - Catlin Acquisition ," as of the Acquisition Date: (U.S. dollars in thousands) Amount Estimated Useful Life Lloyd's - Syndicate capacity $ 660,000 Indefinite Insurance licenses 13,000 Indefinite Total identified indefinite life intangible assets $ 673,000 Lloyd's - Managing agent contracts 15,000 15 years Distribution network 290,000 20 years Trademarks / Trade names 10,000 2 years Total identified definite life intangible assets $ 315,000 Total identified intangible assets $ 988,000

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2015
Reinsurance Disclosures [Abstract]
Effect of reinsurance	The effect of reinsurance and retrocessional activity on premiums written and earned from property and casualty operations is shown below: (U.S. dollars in thousands) Premiums Written Year Ended December 31, Premiums Earned Year Ended December 31, 2015 2014 2013 2015 2014 2013 Direct $ 7,847,236 $ 5,450,868 $ 5,050,953 $ 7,717,173 $ 5,173,403 $ 4,966,207 Assumed 2,821,771 2,310,621 2,365,839 3,465,421 2,343,329 2,363,261 Ceded (2,780,183 ) (1,994,280 ) (1,512,810 ) (3,018,410 ) (1,799,294 ) (1,315,369 ) Net $ 7,888,824 $ 5,767,209 $ 5,903,982 $ 8,164,184 $ 5,717,438 $ 6,014,099
Analysis of losses, loss expenses and future policy benefit reserves recoverables	The following table presents an analysis of total unpaid losses and loss expenses recoverable for the years ended December 31: (U.S. dollars in thousands) 2015 2014 P&C Operations $ 5,248,905 $ 3,411,528 Corporate and Other 13,801 17,840 Total unpaid losses and loss expenses recoverable $ 5,262,706 $ 3,429,368
Ceded credit risk by reinsurer	The following is an analysis of the total recoverable and reinsurance balances receivable, net of collateral held, at December 31, 2015 , by reinsurers owing 3% or more of such total: Name of Reinsurer Reinsurer Financial Strength Rating % of Total Munich Reinsurance Co. AA-/Stable 26.1 % Lloyd's Syndicates A+/Stable 11.7 % Swiss Reinsurance Co. AA-/Stable 6.8 % Swiss Re Europe S.A. AA-/Stable 4.9 % Transatlantic Reinsurance Company A+/Stable 4.3 % Arch Reinsurance Company A+/Stable 3.0 %
Ratings profile of reinsurers	The following table sets forth the ratings profile of the reinsurers that support the unpaid loss and loss expense recoverable and reinsurance balances receivable, net of collateral, at December 31, 2015 : Reinsurer Financial Strength Rating % of Total AAA 3.0 % AA 45.8 % A 47.2 % BBB 0.5 % BB and below 0.7 % Captives 2.7 % Not Rated 0.1 % Total 100.0 %

Losses and Loss Expenses (Table

Losses and Loss Expenses (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting Information [Line Items]
Components of reserves	Unpaid losses and loss expenses for the indicated years ended December 31 are comprised of: (U.S. dollars in thousands) 2015 2014 Reserve for reported losses and loss expenses $ 10,293,448 $ 7,461,444 Reserve for losses incurred but not reported 15,146,296 11,891,799 Unpaid losses and loss expenses $ 25,439,744 $ 19,353,243
Components of incurred losses and loss expenses	Net losses and loss expenses incurred for the years indicated are comprised of: (U.S. dollars in thousands) 2015 2014 2013 Loss and loss expenses payments $ 6,505,075 $ 4,499,642 $ 4,496,802 Change in unpaid losses and loss expenses (168,263 ) (514,406 ) (71,901 ) Change in unpaid losses and loss expenses recoverable (440,189 ) (48,536 ) (24,774 ) Paid loss recoveries (1,130,423 ) (678,307 ) (668,663 ) Net losses and loss expenses incurred $ 4,766,200 $ 3,258,393 $ 3,731,464
Reserve roll forward	The following table represents an analysis of the Company’s paid and unpaid losses and loss expenses incurred and a reconciliation of the beginning and ending unpaid losses and loss expenses for the years indicated: (U.S. dollars in thousands) 2015 2014 2013 Unpaid losses and loss expenses at the beginning of the year $ 19,353,243 $ 20,481,065 $ 20,484,121 Unpaid losses and loss expenses recoverable 3,411,528 3,414,735 3,361,703 Net unpaid losses and loss expenses at the beginning of the year $ 15,941,715 $ 17,066,330 $ 17,122,418 Acquired reserves 5,439,876 — — Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in: Current year 5,072,830 3,513,465 4,021,353 Prior year (306,630 ) (255,072 ) (289,889 ) Total net incurred losses and loss expenses $ 4,766,200 $ 3,258,393 $ 3,731,464 Exchange rate effects (582,300 ) (561,673 ) 40,587 Less net losses and loss expenses paid in respect of losses occurring in: Current year 1,047,277 381,008 425,254 Prior year 4,327,375 3,440,327 3,402,885 Total net paid losses $ 5,374,652 $ 3,821,335 $ 3,828,139 Net unpaid losses and loss expenses at the end of the year 20,190,839 15,941,715 17,066,330 Unpaid losses and loss expenses recoverable 5,248,905 3,411,528 3,414,735 Unpaid losses and loss expenses at the end of the year $ 25,439,744 $ 19,353,243 $ 20,481,065
Schedule of causes of increase (decrease) in liability for unpaid claims and claims adjustment expense [Table Text Block]	The following table presents the net (favorable) adverse prior year loss development of the Company’s loss and loss expense reserves for its property and casualty operations by operating segment for each of the years indicated: (U.S. dollars in thousands) 2015 2014 2013 Insurance segment $ (65,030 ) $ (99,758 ) $ (102,039 ) Reinsurance segment (241,600 ) (155,314 ) (187,850 ) Total $ (306,630 ) $ (255,072 ) $ (289,889 )
Asbestos and environmental related claims rollforward	A reconciliation of the opening and closing unpaid losses and loss expenses related to discontinued asbestos and run-off environmental exposure claims for the years indicated is as follows: Year ended December 31, (U.S. dollars in thousands) 2015 2014 2013 Net unpaid losses and loss expenses at beginning of year $ 81,416 $ 80,435 $ 78,315 Net incurred losses and loss expenses 15,663 8,903 6,257 Less net paid losses and loss expenses 9,087 7,922 4,137 Net increase (decrease) in unpaid losses and loss expenses $ 6,576 $ 981 $ 2,120 Acquired reserves 5,712 — — Net unpaid losses and loss expenses at end of year 93,704 81,416 80,435 Unpaid losses and loss expenses recoverable at end of year 93,688 100,537 115,090 Gross unpaid losses and loss expenses at end of year $ 187,392 $ 181,953 $ 195,525
Schedule of open claims files for potential asbestos and environmental claims	The development of the number of open claim files for potential discontinued asbestos and run-off environmental claims, including precautionary claims, is as follows: Asbestos Claims Environmental Claims Total number of claims outstanding at December 31, 2012 1,073 354 New claims reported in 2013 178 34 Claims resolved in 2013 (154 ) (50 ) Total number of claims outstanding at December 31, 2013 1,097 338 New claims reported in 2014 456 190 Claims resolved in 2014 (154 ) (69 ) Total number of claims outstanding at December 31, 2014 1,399 459 New claims reported in 2015 272 67 Claims resolved in 2015 (246 ) (96 ) Acquired reserves 1,166 — Total number of claims outstanding at December 31, 2015 2,591 430
Insurance Segment [Member]
Segment Reporting Information [Line Items]
Components of prior year development	The following table summarizes the net (favorable) adverse prior year development by line of business relating to the Insurance segment for the indicated years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Professional $ 5,763 $ 17,097 $ 75,045 Casualty (11,949 ) 38,414 (21,829 ) Property 25,189 (57,470 ) (46,387 ) Specialty (120,879 ) (82,756 ) (140,740 ) Other 36,846 (15,043 ) 31,872 Total $ (65,030 ) $ (99,758 ) $ (102,039 )
Reinsurance Segment [Member]
Segment Reporting Information [Line Items]
Components of prior year development	The following table summarizes the net (favorable) adverse prior year development by line of business relating to the Reinsurance segment for the indicated years ended December 31: (U.S. dollars in thousands) 2015 2014 2013 Property and other short-tail lines $ (173,754 ) $ (85,324 ) $ (136,912 ) Casualty and other (67,846 ) (69,990 ) (50,938 ) Total $ (241,600 ) $ (155,314 ) $ (187,850 )

Future Policy Benefit Reserve (

Future Policy Benefit Reserve (Tables)	12 Months Ended
	Dec. 31, 2015
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Funds Withheld on Life Retrocession Arrangements [Table Text Block]	Based upon the contractual right of offset, the funds withheld liability owing to GCLR is recorded net of future policy benefit reserves recoverable, and is included within "Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable)" on the consolidated balance sheets, and is comprised of the following at December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Assets held on a funds withheld basis relating to the GreyCastle Life Retro Arrangements $ 4,633,760 $ 5,420,694 Reinsurance recoverable from GCLR (3,719,131 ) (4,265,678 ) Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable) $ 914,629 $ 1,155,016
Components of future policy benefit reserve	Net future policy benefit reserves are comprised of the following: Year ended December 31 (U.S. dollars in thousands) 2015 2014 Traditional Life $ 792,001 $ 789,133 Annuities 3,371,499 3,918,066 Gross future policy benefit reserves $ 4,163,500 $ 4,707,199 Reinsurance recoverable - GreyCastle Life Retro Arrangements (3,719,131 ) (4,265,678 ) Reinsurance recoverable - U.S. Term Life Retro Arrangements (284,481 ) — Reinsurance recoverable - Other life retrocessions (13,801 ) (17,840 ) Net future policy benefit reserves $ 146,087 $ 423,681

Notes Payable and Debt and Fi49

Notes Payable and Debt and Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Financing structure	The following table presents the Company's outstanding notes payable and debt as of December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Commitment/ In Use/ Commitment/ In Use/ Debt: 2.30% Senior Notes due 2018 $ 300,000 $ 298,015 $ 300,000 $ 297,344 5.75% Senior Notes due 2021 400,000 397,523 400,000 397,092 6.375% Senior Notes due 2024 350,000 349,029 350,000 348,920 4.45% Subordinated Notes due 2025 500,000 492,521 — — 6.25% Senior Notes due 2027 325,000 323,218 325,000 323,062 5.25% Senior Notes due 2043 300,000 296,294 300,000 296,162 5.5% Subordinated Notes due 2045 500,000 488,370 — — Total debt carrying value $ 2,675,000 $ 2,644,970 $ 1,675,000 $ 1,662,580 _______________ (1) Excluded from the table are certain credit facilities under which the Company is permitted to utilize up to $1.4 billion and $1.6 billion as of December 31, 2015 and December 31, 2014 , respectively, for revolving loans to support general operating and financing needs. However, as of December 31, 2015 and December 31, 2014 , $527.1 million and $606.1 million , respectively, were utilized under these facilities to issue letters of credit, leaving $822.9 million and $ 968.9 million , respectively, available to support other operating and financing needs. (2) "In Use/Outstanding" data represent December 31, 2015 and December 31, 2014 accreted values.
Credit facilities	The Company’s available credit facilities at December 31 were as follows: (U.S. dollars in thousands) 2015 (1) 2014 (1) Total available credit facilities – commitments (2) $ 4,463,041 $ 3,575,000 Letters of credit – in use $ 2,515,653 $ 1,790,561 Collateralized by certain assets of the Company’s investment portfolio 50.9 % 66.2 % ____________ (1) As of December 31, 2015 and December 31, 2014 , there were fifteen and eight available credit facilities, respectively. (2) As of December 31, 2015 and December 31, 2014 the stated portion of allowable credit facilities permitted to be utilized for revolving loans was $1.4 billion and $1.6 billion , respectively. However, as of December 31, 2015 and December 31, 2014 , $527.1 million and $606.1 million , respectively, of such facilities' limits were utilized to issue letters of credit, leaving $822.9 million and $ 968.9 million , respectively, available either to issue additional letters of credit or to support other operating or financing needs under these particular facilities.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of location and gross amounts of derivative fair values in the consolidated balance sheets	The following table summarizes information on the location and gross amounts of derivative fair values contained in the consolidated balance sheets at December 31, 2015 and 2014 : (U.S. dollars in thousands) 2015 2014 Asset Derivative Notional Amount Asset Derivative Fair Value (1) Liability Derivative Notional Amount Liability Derivative Fair Value (1) Asset Derivative Notional Amount Asset Derivative Fair Value (1) Liability Derivative Notional Amount Liability Derivative Fair Value (1) Derivatives designated as hedging instruments: Foreign exchange contracts $ 1,667,585 $ 64,289 $ 674,976 $ 11,941 $ 2,300,609 $ 121,862 $ 302,211 $ 2,936 Total derivatives designated as hedging instruments $ 1,667,585 $ 64,289 $ 674,976 $ 11,941 $ 2,300,609 $ 121,862 $ 302,211 $ 2,936 Derivatives not designated as hedging instruments: Investment Related Derivatives: Interest rate exposure $ — $ — $ — $ — $ 394,597 $ 206 $ 20,782 $ 51 Foreign exchange exposure 102,234 2,888 144,707 1,702 7,385 403 207,182 4,442 Credit exposure 8,433 652 71,614 12,067 2,408 165 14,270 9,836 Financial market exposure 37 77 26,500 417 46,145 360 33,670 34 Financial Operations Derivatives: Credit exposure — — — — — — — — Other Non-Investment Derivatives: Foreign exchange contracts 194,566 2,009 — — — — 81,194 282 Credit exposure 29,874 31 — — 31,060 60 — — Guaranteed minimum income benefit contract 46,032 19,368 46,032 19,368 46,249 13,603 46,249 13,603 Modified coinsurance funds withheld contract (2) 60,667 — 4,620,879 — 64,947 — 5,401,278 — Total derivatives not designated as hedging instruments $ 441,843 $ 25,025 $ 4,909,732 $ 33,554 $ 592,791 $ 14,797 $ 5,804,625 $ 28,248 ____________ (1) Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, in the balance sheets on a net basis where the Company has both a legal right of offset and the intention to settle the contracts on a net basis. (2) The fair value movements in derivative assets and liabilities relating to modified coinsurance funds withheld contracts are included within the associated asset or liability at each period end on the face of the balance sheets. Notional amounts associated with reinsurance agreements under which the Company assumes reinsurance risk are recorded as asset derivative notional amounts. Notional amounts associated with the GreyCastle Life Retro Arrangements under which the Company cedes reinsurance risk are recorded as liability derivative notional amounts. Included in the liability derivative notional amount at December 31, 2015 is the cumulative net realized and unrealized loss on life retrocession embedded derivative of $463.9 million .
Summary of gross and net amounts of derivative fair values and associated collateral	The following table summarizes information on the gross and net amounts of derivative fair values and associated collateral received related to derivative assets, or collateral provided relating to derivative liabilities reported in other assets and other liabilities within the consolidated balance sheets at December 31, 2015 and 2014 : Gross Amounts Not Offset in the Balance Sheets December 31, 2015 (U.S. dollars in thousands) Gross Amounts Recognized in the Balance Sheets Gross Amounts Offset in the Balance Sheets Net Amounts in the Balance Sheets Financial Instruments Cash Collateral Net Amounts Derivative Assets $ 89,314 $ 3,087 $ 86,227 $ — $ 30,958 $ 55,269 Derivative Liabilities $ 45,495 $ 3,087 $ 42,408 $ — $ — $ 42,408 December 31, 2014 (U.S. dollars in thousands) Derivative Assets $ 136,659 $ 696 $ 135,963 $ — $ 78,580 $ 57,383 Derivative Liabilities $ 31,184 $ 696 $ 30,488 $ — $ — $ 30,488
Total impact on earnings related to derivative instruments	The following table provides the total impact on earnings relating to derivative instruments formally designated as fair value hedges along with the impacts of the related hedged items for the years indicated: Derivatives Designated as Fair Value Hedges (U.S. dollars in thousands) Hedged Items – Amount of Gain/(Loss) Recognized in Income Attributable to Risk Gain/(Loss) Recognized in Income on Derivative Deposit Liabilities Fixed Maturity Investments Ineffective Portion of Hedging Relationship – Gain/(Loss) Year Ended December 31, 2015 Interest rate exposure $ — Foreign exchange exposure — Total $ — $ — $ — $ — Year Ended December 31, 2014 Interest rate exposure $ — Foreign exchange exposure (15,663 ) Total $ (15,663 ) $ — $ 15,407 $ (256 ) Year Ended December 31, 2013 Interest rate exposure $ — Foreign exchange exposure (22,568 ) Total $ (22,568 ) $ — $ 23,065 $ 497
Summary of fair value hedges that have been settled and their impact on results during the year	A summary of the fair value hedges that have been settled and their impact on results during the indicated years ended December 31 as well as the remaining balance of fair value hedges and average years remaining to maturity are shown below: Settlement of Fair Value Hedges – Summary (U.S. dollars in thousands, except years) Fair Value Hedges – Notes Payable and Debt December 31, Fair Value Hedges – Deposit Liabilities December 31, 2015 2014 2015 2014 Cumulative reduction to interest expense $ — $ 21,624 $ 103,742 $ 95,333 Remaining balance $ — $ — $ 129,454 $ 137,862 Weighted average years remaining to maturity 0.0 0.0 21.6 23.2
Weighted average US dollar equivalent of foreign denominated net assets that were hedge and resultant gain (loss)	The following table provides the weighted average U.S. dollar equivalent of foreign denominated net assets that were hedged and the resulting derivative gain (loss) that was recorded in the foreign currency translation adjustment, net of tax, account within AOCI for the years ended December 31, 2015 and 2014 . Derivative Instruments Designated as Hedges of the Net Investment in a Foreign Operation – Summary (U.S. dollars in thousands) 2015 2014 Weighted average of U.S. dollar equivalent of foreign denominated net assets $ 1,769,106 $ 2,384,508 Derivative gains (losses) (1) $ 106,876 $ 120,643 ____________ (1) Derivative gains (losses) from derivative instruments designated as hedges of the net investment in a foreign operation are recorded in the cumulative translation adjustment account within AOCI for each period.
Total impact on earnings relating to derivative instruments not formally designated as hedging	The following table provides the total impact on earnings relating to derivative instruments not formally designated as hedging instruments under GAAP and from the ineffective portion of fair value hedges. The impacts are all recorded through Net realized and unrealized gains (losses) on derivatives in the income statement for the years ended December 31, 2015, 2014 and 2013 : Net Realized and Unrealized Gains (Losses) on Derivative Instruments (U.S. dollars in thousands) 2015 2014 2013 Investment Related Derivatives: Interest rate exposure $ (2,347 ) $ 15,959 $ 5,065 Foreign exchange exposure (1,542 ) 3,351 (948 ) Credit exposure (2,537 ) 400 (4,052 ) Financial market exposure (2,190 ) 411 6,302 Financial Operations Derivatives: Credit exposure — 5,023 (2,437 ) Other Non-Investment Derivatives: Foreign exchange exposure 60,319 — — Credit exposure 1,375 — — Guaranteed minimum income benefit contract — 2,257 10,457 Modified coinsurance funds withheld contract 45 2,741 (7,086 ) Total derivatives not designated as hedging instruments $ 53,123 $ 30,142 $ 7,301 Amount of gain (loss) recognized in income from ineffective portion of fair value hedges — (256 ) 497 Net realized and unrealized gains (losses) on derivative instruments $ 53,123 $ 29,886 $ 7,798 Net realized and unrealized gains (losses on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (151,691 ) $ (488,222 ) $ —
Components of life retrocession embedded derivatives	The change in the value of the life retrocession embedded derivative includes the interest income, realized and unrealized gains and losses on Life Funds Withheld Assets and certain related expenses subsequent to May 30, 2014 as follows: Components of Life Retrocession Embedded Derivative and Derivative Instruments - Life Funds Withheld Assets: (U.S. dollars in thousands) 2015 2014 Interest income - Life Funds Withheld Assets $ (193,568 ) $ (134,634 ) Realized and unrealized gains (losses) on Life Funds Withheld Assets 180,134 (318,065 ) Other 351 1,868 Net realized and unrealized gains (losses) on life retrocession embedded derivative $ (13,083 ) $ (450,831 ) Net adjustments related to future policy benefit reserves, net of tax $ (125,747 ) $ (21,786 ) Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets $ (12,861 ) $ (15,605 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (151,691 ) $ (488,222 )
Summary of contingent credit features	The aggregate fair value of all derivative agreements containing such rating downgrade provisions that were in a liability position and any collateral posted under these agreements at December 31 for the years indicated were as follows: Contingent Credit Features - Summary: (U.S. dollars in thousands) 2015 2014 Aggregate fair value of derivative agreements with downgrade provisions in a net liability position $ 5,827 $ 5,770 Collateral posted to counterparty $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Broker credit risk	During the three years ended December 31, 2015, 2014 and 2013 , P&C gross written premiums generated from or placed by the below companies individually accounted for more than 10% of the Company’s consolidated gross written premiums from P&C operations, as follows: (Percentage of consolidated gross written premiums from P&C operations) 2015 2014 2013 AON Corporation and subsidiaries 18 % 18 % 21 % Marsh & McLennan Companies 19 % 20 % 23 % Willis Group and subsidiaries 13 % 11 % 13 %
Future minimum lease payments - operating	Future minimum rental commitments under existing operating leases are expected to be as follows: Year Ended December 31, (U.S. dollars in thousands) 2016 $ 69,256 2017 62,517 2018 56,122 2019 51,447 2020 46,356 2021-2031 131,826 Total minimum future rentals $ 417,524
Future minimum lease payments - capital lease	The future minimum lease payments in the aggregate are expected to be $171.6 million and annually for the next five years are as follows: Year Ended December 31, (U.S. dollars in thousands) 2016 $ 11,870 2017 12,167 2018 12,471 2019 12,783 2020 13,103 2021-2028 109,248 Total minimum future lease payments $ 171,642

Share Capital (Tables)

Share Capital (Tables)	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Summary of ordinary shares issued and outstanding	The following table is a summary of ordinary shares issued and outstanding: (in thousands) 2015 2014 Balance – beginning of year 255,183 278,253 Exercise of options 480 424 Net issuance of restricted shares 1,581 1,246 Share buybacks (1) (12,434 ) (24,740 ) Issue of shares 49,935 — Balance – end of year 294,745 255,183 ____________ (1) Includes share buybacks associated with authorized share buyback programs as well as purchases related to satisfying tax withholding obligations of employees in connection with the vesting of restricted shares granted under the Company’s equity compensation programs.
Weighted average option pricing assumptions	The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: 2015 2014 2013 Dividend yield 2.00 % 2.00 % 2.00 % Risk free interest rate 1.70 % 1.81 % 1.14 % Volatility 21.6 % 34.0 % 37.0 % Expected lives 6.0 years 6.0 years 6.0 years
Summary of options and options activity	The following is a summary of the activity in the stock option plans for the indicated years ended December 31: (In thousands except for weighted average grant date fair value) 2015 2014 2013 Options granted to purchase ordinary shares under the Programs - in thousands 1,974 1,025 1,047 Weighted average grant date fair value $ 6.51 $ 8.60 $ 8.34 Total intrinsic value of stock options exercised $ 8,546 $ 7,499 $ 16,076 Options exercised during the year - in thousands 480 424 927 Compensation expense related to stock option plans $ 8,961 $ 9,961 $ 8,294 Estimated tax benefit (charge) related to stock option plans $ — $ (2 ) $ 50 The following is a summary of the stock options outstanding at December 31, 2015 , and related activity for the year then ended: Number of Shares ( in thousands ) Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) Outstanding – beginning of year 10,525 $ 32.42 4.8 years $ 86,690 Granted 1,974 36.43 Exercised (480 ) 20.79 Canceled/Expired (1,270 ) 75.34 Outstanding – end of year 10,749 $ 28.59 5.4 years $ 121,085 Options exercisable 7,741 $ 26.43 4.1 years $ 105,990 Available for grant (1) 6,907 ____________ (1) Available for grant includes shares that may be granted as either stock options, restricted stock, restricted stock units or performance units.
Summary of restricted stock and non-vested restricted stock activity	Non-vested restricted stock awards at December 31, 2015 and for the year then ended were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 433 $ 36.41 Granted 44 $ 37.11 Vested (202 ) $ 29.08 Unvested at December 31, 2015 275 $ 41.90 A summary of the restricted stock awards issued under the 1991 Performance Incentive Program and the Directors Stock and Option Plan for the indicated years ended December 31 is as follows: (In thousands except for weighted average grant date fair value) 2015 2014 2013 Restricted ordinary shares granted 44 46 181 Weighted average grant date fair value $ 37.11 $ 31.86 $ 29.44 Aggregate grant date fair value $ 1,613 $ 1,463 $ 5,325 Compensation expense related to restricted stock awards $ 3,889 $ 5,239 $ 4,419 Estimated tax benefit related to restricted stock awards $ 709 $ 1,233 $ 1,047
Summary of restricted stock units and restricted stock unit activity	A summary of the restricted stock units issued to officers of the Company and its subsidiaries for the indicated years ended December 31 is as follows: (In thousands) 2015 2014 2013 Restricted stock units granted 1,534 1,867 1,803 Aggregate grant date fair value $ 55,540 $ 57,134 $ 51,829 Compensation expense related to restricted stock units $ 48,937 $ 41,879 $ 32,874 Estimated tax benefit related to restricted stock units $ 13,271 $ 11,607 $ 8,813 Non-vested restricted stock units at December 31, 2015 and for the year then ended were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 3,248 $ 28.93 Granted 1,534 $ 36.20 Vested (1,536 ) $ 27.67 Forfeited (176 ) $ 32.45 Unvested at December 31, 2015 3,070 $ 32.99
Summary of performance units and performance units activity	A summary of the performance units issued to certain employees of the Company for the indicated years ended December 31 is as follows: (In thousands) 2015 2014 2013 Performance units granted 781 572 656 Potential maximum share payout 1,563 1,144 1,312 Aggregate grant date fair value $ 28,082 $ 16,345 $ 17,753 Compensation expense related to performance units $ 12,942 $ 24,089 $ 1,041 Estimated tax benefit (charge) related to performance units $ 1,459 $ 4,250 $ (176 ) Non-vested restricted performance units as of December 31, 2015 were as follows: (In thousands except for weighted average grant date fair value) Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 2,540 $ 25.24 Granted 781 $ 35.94 Vested (750 ) $ 19.35 Forfeited (63 ) $ 30.03 Performance driven addition (reduction) (627 ) $ 27.74 Unvested at December 31, 2015 1,881 $ 31.02

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Funded status by geographical region	The funded status by geographical region of all the Company’s retirement plans at December 31, 2015 and 2014 is as follows: Funded Status 2015 2014 U.S. $ (16,306 ) $ (13,124 ) U.K. (4,650 ) (7,742 ) Other European (21,807 ) (22,977 ) Funded status – end of year $ (42,763 ) $ (43,843 )
Change in projected benefit obligation	Change in projected benefit obligation (U.S. dollars in thousands) 2015 2014 Projected benefit obligation – beginning of year $ 93,124 $ 81,976 Projected benefit obligation assumed due to Catlin Acquisition 28,414 — Service cost (1) 1,494 1,279 Interest cost 4,382 3,747 Actuarial (gain) / loss 2,821 13,402 Benefits and expenses paid (3,747 ) (2,761 ) Foreign currency (gains) / losses (4,047 ) (3,817 ) Settlements (276 ) (702 ) Projected benefit obligation – end of year $ 122,165 $ 93,124 (1) Service costs include cost of living adjustments on curtailed plans.
Change in plan assets	Change in plan assets (U.S. dollars in thousands) 2015 2014 Fair value of plan assets – beginning of year $ 49,281 $ 47,158 Fair value of plan assets acquired due to Catlin Acquisition 33,131 — Actual return on plan assets (119 ) 3,543 Employer contributions 1,775 1,187 Benefits and expenses paid (3,305 ) (1,932 ) Foreign currency gains / (losses) (1,361 ) (675 ) Fair value of plan assets – end of year $ 79,402 $ 49,281 Funded status – end of year $ (42,763 ) $ (43,843 ) Accrued pension liability $ 42,763 $ 43,843
Components of net benefit cost	The components of the net benefit cost for the years ended December 31, 2015, 2014 and 2013 are as follows: Components of net benefit cost (U.S. dollars in thousands) 2015 2014 2013 Service cost $ 1,494 $ 1,279 $ 1,491 Interest cost 4,381 3,747 3,589 Expected return on plan assets (3,903 ) (2,859 ) (3,096 ) Amortization of net actuarial loss 1,617 812 1,440 Net benefit cost $ 3,589 $ 2,979 $ 3,424
Weighted average assumptions used	The table below includes disclosure of these rates on a weighted-average basis, for the years ended December 31 as indicated: 2015 2014 U.S. Plans U.K. Plans Other European Plans U.S. Plans U.K. Plans Other European Plans Net Benefit Cost – Weighted-average assumptions Discount rate 3.91 % 3.70 % 2.42 % 4.95 % 4.60 % 3.50 % Expected long-term rate of return on plan assets 6.00 % 3.48 % N/A 6.50 % 4.60 % N/A Rate of compensation increase N/A 3.96 % 2.50 % N/A 5.50 % 2.50 % Benefit Obligation – Weighted-average assumptions Discount rate 4.25 % 3.70 % 2.42 % 3.91 % 4.60 % 2.40 % Rate of compensation increase N/A 3.96 % 2.50 % N/A 5.50 % 2.50 %
Allocation of plan assets - UK pension	The assets in the plans and the expected rates of return were as follows: (U.S. dollars in thousands, except percentages) Expected Return on Assets for 2015 Fair Value at December 31, 2015 Expected Return on Assets for2014 Fair Value at December 31,2014 Equities 6.2 % $ 7,893 7.4 % $ 7,787 Gilts 2.4 % 17,856 3.6 % 1,579 Corporate Bonds 3.4 % 16,915 4.6 % 1,594 Other (cash) 1.8 % 52 4.0 % 224 Total market fair value of assets $ 42,716 $ 11,184
Estimated future benefit payments	The estimated future benefit payments with respect to the U.S. defined benefit pension plans are as follows: (U.S. dollars in thousands) Retirement Plan Benefits Equalization Plan Total 2016 $ 988 $ 434 $ 1,422 2017 $ 1,023 $ 430 $ 1,453 2018 $ 1,054 $ 427 $ 1,481 2019 $ 1,240 $ 524 $ 1,764 2020 $ 1,396 $ 538 $ 1,934 2021-2025 $ 9,904 $ 3,032 $ 12,936

Accumulated Other Comprehensi54

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2015
Comprehensive Income Loss Note [Abstract]
Components of acculumated other comprehensive income (loss)	The changes in AOCI, net of tax, by component for the indicated years ended December 31 are as follows: (U.S. dollars in thousands) Unrealized Gains (Losses) on Investments (1) OTTI Losses Recognized in AOCI Foreign Currency Translation Adjustments Underfunded Pension Liability Cash Flow Hedge Total Balance, net of tax, December 31, 2012 $ 1,591,210 $ (121,371 ) $ 69,399 $ (20,892 ) $ 1,674 $ 1,520,020 OCI before reclassifications (742,768 ) — (62,934 ) 9,722 — (795,980 ) Amounts reclassified from AOCI (119,970 ) 32,193 206 1,440 439 (85,692 ) Tax benefit (expense) 93,960 (12 ) 7,870 (3,509 ) — 98,309 Net current period OCI - net of tax $ (768,778 ) $ 32,181 $ (54,858 ) $ 7,653 $ 439 $ (783,363 ) Balance, net of tax, December 31, 2013 $ 822,432 $ (89,190 ) $ 14,541 $ (13,239 ) $ 2,113 $ 736,657 OCI before reclassifications (1) 954,326 — (26,497 ) (10,877 ) — 916,952 Amounts reclassified from AOCI (143,330 ) 14,082 87 812 255 (128,094 ) Tax benefit (expense) (43,314 ) (939 ) 681 2,515 — (41,057 ) Net current period OCI - net of tax $ 767,682 $ 13,143 $ (25,729 ) $ (7,550 ) $ 255 $ 747,801 Balance, net of tax, December 31, 2014 $ 1,590,114 $ (76,047 ) $ (11,188 ) $ (20,789 ) $ 2,368 $ 1,484,458 OCI before reclassifications (1) (474,304 ) — (33,690 ) (6,100 ) — (514,094 ) Amounts reclassified from AOCI (346,911 ) 18,987 — 1,145 (200 ) (326,979 ) Tax benefit (expense) 34,195 (442 ) 8,375 1,103 — 43,231 Net current period OCI - net of tax $ (787,020 ) $ 18,545 $ (25,315 ) $ (3,852 ) $ (200 ) $ (797,842 ) Balance, net of tax, December 31, 2015 $ 803,094 $ (57,502 ) $ (36,503 ) $ (24,641 ) $ 2,168 $ 686,616 ____________ (1) Included in these amounts is the impact of Shadow Adjustments. As of December 31, 2014, $445.1 million was recorded. During the year ended December 31, 2015 , additional net impacts of $(170.7) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $274.4 million at December 31, 2015 .
Reclassifications out of AOCI	The reclassifications out of AOCI along with the associated income statement line items affected by component, and the total related tax (expense) benefit for indicated years ended December 31, are as follows: Gross Amount Reclassified From AOCI Details About AOCI Components (U.S. dollars in thousands) 2015 2014 Affected Line Item in the Statement of Income Unrealized gains and losses on investments: $ (316,508 ) $ (175,639 ) Net realized gains (losses) on investments sold 95,344 $ 54,095 OTTI on investments (125,747 ) $ (21,786 ) Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets $ (346,911 ) $ (143,330 ) Total before tax 7,597 $ (1,593 ) Provision (benefit) for income tax $ (339,314 ) $ (144,923 ) Net of tax OTTI losses recognized in OCI: $ 18,014 $ 11,848 Net realized gains (losses) on investments sold 973 $ 2,234 OTTI on investments transferred to (from) OCI $ 18,987 $ 14,082 Total before tax (32 ) $ (175 ) Provision (benefit) for income tax $ 18,955 $ 13,907 Net of tax Foreign Currency Translation: Foreign exchange relating to affiliate investments $ — $ 87 Exchange gains (losses) - before tax — $ — Provision (benefit) for income tax $ — $ 87 Net of tax Underfunded Pension Liability: Pension expense $ 1,145 $ 812 Operating Expenses (401 ) $ (206 ) Provision (benefit) for income tax $ 744 $ 606 Net of tax Gains and losses on cash flow hedges: Interest rate contracts $ (200 ) $ 255 Interest Expense — $ — Provision (benefit) for income tax $ (200 ) $ 255 Net of tax Total reclassifications for the period, gross of tax $ (326,979 ) (128,094 ) Tax (benefit) expense 7,164 (1,974 ) Total reclassifications for the period, net of tax $ (319,815 ) (130,068 )

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2015
Dividends Disclosure [Abstract]
Schedule of dividends paid	preference shareholders for the indicated years ended December 31, as follows: (U.S. dollars in millions) 2015 2014 2013 Series D preference ordinary shares (1) (2) $ 11.8 $ 11.7 $ 12.3 Series E preference ordinary shares (3) $ 65.1 $ 65.1 $ 65.1 Non-cumulative perpetual preferred shares (4) $ 21.8 $ — $ — ____________ (1) On October 30, 2015 , the Company announced that the Board of Directors of XL-Cayman resolved to pay a dividend of $8.7787 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend was paid on January 15, 2016 to all shareholders of record at January 1, 2016 . (2) On February 19, 2016 , the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $9.349 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016 . (3) On February 19, 2016 , the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $32.50 per share on XL-Cayman’s Series E Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016 . (4) On January 12, 2016 , the Board of Directors of Catlin-Bermuda resolved to pay a dividend in the aggregate amount of $21.8 million on CICL Prefs. The dividend was paid on January 19, 2016 to all shareholders of record at December 31, 2015 .

Taxation (Tables)

Taxation (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Summary of income tax examinations	The following table details the years that are the subject of open examinations, by major tax jurisdiction. While the Company cannot estimate with certainty the outcome of these examinations, the Company does not believe that adjustments from open tax years will result in a significant change to the Company's results from operations. Jurisdiction Tax Years U.S. 2013 Ireland 2006 - 2009 Germany 2010 - 2013 France 2013 - 2014 The following table details open tax years that are open to assessment by local tax authorities, in the following major tax jurisdictions. Jurisdiction Tax Years U.S. 2012 - 2015 Ireland 2006 - 2015 U.K. 2013 - 2015 Germany 2010 - 2015 Switzerland 2011 - 2015 France 2013 - 2015
Distribution of income (loss) before income tax, by jurisdiction	The Company’s income (loss) before income tax and non-controlling interests was distributed between U.S. and non-U.S. for the years ended December 31, 2015, 2014 and 2013 as follows: Income (loss) before income tax: (U.S. dollars in thousands) 2015 2014 2013 U.S. $ (5,931 ) $ 228,708 $ 188,503 Non U.S. 1,300,109 137,027 1,025,649 Total $ 1,294,178 $ 365,735 $ 1,214,152
Components of income tax expense	The income tax provisions for the years ended December 31, 2015, 2014 and 2013 were as follows: (U.S. dollars in thousands) 2015 2014 2013 Current expense (benefit): U.S. $ (22,698 ) $ 45,598 $ 49,566 Non U.S. 67,784 81,371 41,921 Total current expense (benefit) $ 45,086 $ 126,969 $ 91,487 Deferred expense (benefit): U.S. $ (63,491 ) $ 8,572 $ 700 Non U.S. (756 ) (38,644 ) (14,682 ) Total deferred expense (benefit) $ (64,247 ) $ (30,072 ) $ (13,982 ) Total tax expense (benefit) $ (19,161 ) $ 96,897 $ 77,505
Applicable statutory tax rates by jurisdiction	The applicable statutory tax rates of the most significant jurisdictions contributing to the overall taxation of the Company are: Jurisdiction Applicable Statutory Taxation Rates Ireland (1) 12.50 % Ireland (1) 25.00 % Bermuda — % U.S. 35.00 % U.K. 20.25 % Switzerland (2) 7.83 % Switzerland (2) 21.20 % Germany 15.00 % France 38.00 % ____________ (1) The different applicable statutory taxation rates in Ireland relate to entities classified as trading or non-trading companies. (2) The different applicable statutory taxation rates in Switzerland relate to entities classified as trading or holding companies
Reconciliation of effective tax rate	A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate for the years ended December 31, 2015, 2014 and 2013 is provided below: (U.S. dollars in thousands) 2015 2014 2013 Expected tax (benefit) provision at weighted average rate $ (50,797 ) $ 132,775 $ 43,092 Permanent differences: Non-taxable (income) loss (23,036 ) (19,870 ) (50,745 ) Revision to prior year estimates 7,402 2,016 8,551 State, local and foreign taxes 27,499 47,078 12,225 Valuation allowance 9,517 (181 ) 5,754 Net allocated investment income (405 ) 3,399 5,949 Stock options (433 ) 411 1,501 Non-deductible expenses 42,839 22,556 23,662 Other investment related adjustments 2,075 (2,916 ) — Adjustments related to GreyCastle Life Retro Arrangements (35,045 ) (99,535 ) — Change in tax rates (11,877 ) 3,974 (2,484 ) Uncertain tax positions 13,100 7,190 30,000 Total tax expense (benefit) $ (19,161 ) $ 96,897 $ 77,505
Components of net deferred tax assets	Significant components of the Company’s deferred tax assets and liabilities at December 31, 2015 and 2014 were as follows: (U.S. dollars in thousands) 2015 2014 Deferred tax asset: Net unpaid loss reserve discount $ 111,584 $ 90,262 Net unearned premiums 80,434 72,752 Compensation liabilities 94,013 77,578 Net operating losses 181,295 49,834 Investment adjustments 14,399 13,022 Pension 10,370 8,114 Bad debt reserve 7,425 6,626 Amortizable goodwill 5,396 6,694 Net unrealized depreciation on investments 5,051 1,484 Stock options 16,192 11,985 Depreciation 13,299 7,599 Net realized capital losses 98,756 97,189 Deferred intercompany capital losses 26,164 57,427 Untaxed Lloyd's result 3,769 7,254 Deferred acquisition costs 31,133 11,386 Currency translation adjustments 6,280 — Other 24,977 2,282 Deferred tax asset, gross of valuation allowance $ 730,537 $ 521,488 Valuation allowance 276,301 207,062 Deferred tax asset, net of valuation allowance $ 454,236 $ 314,426 (U.S. dollars in thousands) 2015 2014 Deferred tax liability: Net unrealized appreciation on investments $ 51,010 $ 63,642 Unremitted earnings $ 3,739 $ 5,125 Deferred acquisition costs 8,308 2,737 Currency translation adjustments 1,210 3,969 Regulatory reserves 64,352 65,965 Investment adjustment 6,373 12,061 Untaxed Lloyd’s result — 11,422 Depreciation 11,500 — Syndicate capacity 92,756 — Intangible asset 40,126 — Other 13,202 11,260 Deferred tax liability $ 292,576 $ 176,181 Net Deferred Tax Asset $ 161,660 $ 138,245
Summary of valuation allowance	At December 31, 2015 and 2014 , the valuation allowance of $276.3 million and $207.1 million , respectively, related primarily to net operating loss and realized capital loss carryforwards in the following jurisdictions: Jurisdiction (U.S. dollars in thousands) 2015 2014 Switzerland $ 7,818 $ 1,459 Ireland 93,396 72,363 U.S. 106,624 123,695 U.K. 46,732 1,632 Other 21,731 7,913 Valuation Allowance Total $ 276,301 $ 207,062
Reconciliation of unrecognized tax benefits	The following table presents a reconciliation of the Company’s unrecognized tax benefits: (U.S. dollars in thousands) 2015 2014 2013 Unrecognized tax benefits, beginning of the year $ 37,190 $ 30,000 $ — Increases for tax positions taken during the year 20,370 12,182 9,591 Increases for tax positions taken in prior years (1) 38,650 15,304 20,409 Decreases for tax positions taken in prior years (4,850 ) (20,296 ) — Decreases for lapse of the applicable statute of limitations (10,770 ) — — Unrecognized tax benefits, end of year $ 80,590 $ 37,190 $ 30,000

Statutory Financial Data (Table

Statutory Financial Data (Tables)	12 Months Ended
	Dec. 31, 2015
Statutory Capital And Surplus Disclosure Text Block [Abstract]
Schedule of statutory capital	Statutory capital and surplus for the principal operating subsidiaries of the Company for the years ended December 31, 2015 and 2014 are summarized below: (U.S. dollars in thousands) Bermuda (1) U.S. (2) U.K., Europe and Other 2015 2014 2015 2014 2015 2014 Required statutory capital and surplus $ 7,722,123 $ 6,194,832 $ 747,313 $ 668,794 $ 4,445,247 $ 1,604,721 Actual statutory capital and surplus (3) $ 11,112,176 $ 10,309,895 $ 2,234,767 $ 2,233,596 $ 6,054,122 $ 2,712,552 ____________ (1) Required statutory capital and surplus at December 31, 2015 represents 100% Bermuda Solvency Capital Requirement ("BSCR") level for the top Bermuda operating subsidiary, XL Insurance (Bermuda) Ltd, calculated on a consolidated basis (and therefore includes a BSCR requirement for all regions). (2) Required statutory capital and surplus represents 100% Risk-Based Capital level for principal U.S. operating subsidiaries. (3) Statutory assets in Bermuda include investments in other U.S. and international subsidiaries reported separately herein.
Schedule of statutory net income loss	Statutory net income (loss) for the principal operating subsidiaries of the Company for the years ended December 31, 2015, 2014 and 2013 is summarized below: (U.S. dollars in thousands) 2015 2014 2013 Bermuda $ 1,513,924 $ 361,022 $ 1,241,878 U.S. $ 17,574 $ 155,751 $ 124,310 U.K., Europe and Other $ (125,758 ) $ 215,787 $ 1,465

Computation of Earnings Per O58

Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per share	The following table sets forth the computation of basic and diluted earnings per ordinary share for the years ended December 31, 2015, 2014 and 2013 : (U.S. dollars in thousands, except per share amounts) 2015 2014 2013 Basic earnings per ordinary share and ordinary share equivalents outstanding: Net income (loss) attributable to ordinary shareholders $ 1,207,152 $ 188,340 $ 1,059,916 Weighted average ordinary shares outstanding 286,194 267,103 287,801 Basic earnings per ordinary share and ordinary share equivalents outstanding $ 4.22 $ 0.71 $ 3.68 Diluted earnings per ordinary share and ordinary share equivalents outstanding: Weighted average ordinary shares outstanding – basic 286,194 267,103 287,801 Impact of share based compensation 4,805 4,424 4,268 Weighted average ordinary shares outstanding – diluted 290,999 271,527 292,069 Diluted earnings per ordinary share & ordinary share equivalents outstanding $ 4.15 $ 0.69 $ 3.63 Dividends per ordinary share $ 0.72 $ 0.64 $ 0.56

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Summary of related party transactions	(U.S. dollars in thousands) 2015 2014 2013 Reported net premiums $ 42,042 $ 91,261 $ 73,085 Reported net losses $ 13,246 $ 38,927 $ 29,042 Reported net acquisition costs $ 14,682 $ 35,711 $ 25,275

Unaudited Quarterly Financial60

Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly financial data	The following is a summary of the unaudited quarterly financial data for 2015 and 2014 : (U.S. dollars in thousands, except per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Net premiums earned – P&C operations $ 1,319,494 $ 2,063,795 $ 2,405,740 $ 2,375,155 Net premiums earned – Corporate and Other $ 14,506 $ 18,258 $ 17,812 $ 11,665 Underwriting profit (loss) – P&C operations $ 146,836 $ 208,779 $ 114,118 $ 183,458 Net income (loss) attributable to ordinary shareholders $ 36,281 $ 915,039 $ 27,282 $ 228,550 Net income (loss) per ordinary share and ordinary equivalent – basic $ 0.14 $ 3.16 $ 0.09 $ 0.77 Net income (loss) per ordinary share and ordinary equivalent – diluted $ 0.14 $ 3.11 $ 0.09 $ 0.76 2014 Net premiums earned – P&C operations $ 1,412,528 $ 1,438,076 $ 1,453,673 $ 1,413,161 Net premiums earned – Corporate and Other $ 76,311 $ 58,518 $ 19,739 $ 23,064 Underwriting profit (loss) – P&C operations $ 144,874 $ 167,947 $ 144,375 $ 218,850 Net income (loss) attributable to ordinary shareholders $ 255,717 $ (279,260 ) $ 72,384 $ 139,499 Net income (loss) per ordinary share and ordinary equivalent – basic $ 0.93 $ (1.03 ) $ 0.27 $ 0.54 Net income (loss) per ordinary share and ordinary equivalent – diluted $ 0.91 $ (1.03 ) $ 0.27 $ 0.53

General (Details)

General (Details)	12 Months Ended
	Dec. 31, 2015segmentscountry
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Countries in which Entity Operates | country	29
Number of Operating Segments | segments	2

Significant Accounting Polici62

Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Significant Accounting Policies [Line Items]
Premiums Earned and Associated Tax Accruals Adjustment Amount	$ 20
Options, life of award	10 years
Hedge funds
Significant Accounting Policies [Line Items]
Alternative investments, timelag for reporting	1 month
Private investment funds
Significant Accounting Policies [Line Items]
Alternative investments, timelag for reporting	3 months
Operating affiliates
Significant Accounting Policies [Line Items]
Alternative investments, timelag for reporting	3 months
Maximum
Significant Accounting Policies [Line Items]
Vesting period required	4 years
Minimum
Significant Accounting Policies [Line Items]
Vesting period required	3 years

Acquisitions and Disposals - Al

Acquisitions and Disposals - Allied Acquisition (Details) - Subsequent Event [Member] - Allied International Holdings, Inc. [Member] $ in Millions	Feb. 01, 2016USD ($)
Business Acquisition [Line Items]
Cash consideration	$ 75.6
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	7.5
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	30
Business Combination, Contingent Consideration, Liability	15
Acquisition consideration	$ 90.6

Acquisitions and Disposals - Ne

Acquisitions and Disposals - New Energy Risk narrative (Details) - USD ($) $ in Thousands	Jul. 24, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill, acquired during period		$ 807,381	$ 25,159
New Energy Risk Inc. [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	63.63%
Business combination, step acquisition, equity interest in acquiree, percentage	31.16%
Business combination, step acquisition, equity interest in acquiree, including subsequent acquisition, percentage	94.79%
Noncontrolling interest, ownership percentage by noncontrolling owners	5.21%
Cash consideration	$ 8,800
Business combination, step acquisition, equity interest in acquiree, remeasurement gain	2,500
Goodwill, acquired during period	$ 13,400

Acquisitions and Disposals - Ca

Acquisitions and Disposals - Catlin Acquisition narrative (Details) £ / shares in Units, $ / shares in Units, £ in Thousands, $ in Thousands		Sep. 28, 2015USD ($)	May. 01, 2015USD ($)shares$ / shares	May. 01, 2015GBP (£)shares£ / shares	Dec. 31, 2015USD ($)$ / shares	Dec. 31, 2014USD ($)$ / shares	Mar. 30, 2015USD ($)	Jan. 08, 2015GBP (£)
Business Acquisition [Line Items]
Ordinary shares, par value (in dollars per share) | $ / shares					$ 0.01	$ 0.01
Debt instrument, face amount	[1]				$ 2,675,000	$ 1,675,000
Goodwill, acquired during period					807,381	25,159
Indefinite-lived Intangible Assets Acquired					673,000
Finite-lived Intangible Assets Acquired					315,000	$ 18,500
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount					(69,200)
Catlin Group Limited [Member]
Business Acquisition [Line Items]
Ordinary shares, par value (in dollars per share) | $ / shares			$ 0.01
Cash price component, per Catlin Share in GBP | £ / shares				£ 3.88
Exchange ratio per the Implementation Agreement | shares			0.13	0.13
XL Share issuance to Catlin shareholders | shares			49,935,000	49,935,000
Cash consideration			$ 2,287,579	£ 1,490,377
Debt instrument, face amount							$ 1,000,000
Goodwill, acquired during period	[2]		793,990
Goodwill, Purchase Accounting Adjustments					$ 15,900
Indefinite-lived Intangible Assets Acquired			673,000
Finite-lived Intangible Assets Acquired			315,000
Business Combination Measurement Period					12 months
Value of Business Acquired Adjustment, Amortization Period					2 years
Intangibles Assets Arising from Insurance Contracts Acquired in Business Combination, Amortization Expense					$ 471,000
Unpaid Losses And Loss Expenses Adjustment Amortization Period					20 years
Business Combination Initial Accounting Incomplete Other Assets					$ (7,500)
Business Combination Initial Accounting Incomplete Deferred Tax Liabilities					(11,300)
Business Combination Initial Accounting Incomplete Other Liabilities					19,800
Deferred tax liability	[2]		82,783
Business Combination, Acquisition Related Costs					64,700
Catlin Inc [Member]
Business Acquisition [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ (59,600)
XL Cayman [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Available letter of credit facilities - commitments | £								£ 1,600,000
XL Ireland [Member] | Catlin Inc [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired		100.00%
Proceeds From Debt [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Cash consideration			980,600
Cash and Cash Equivalents [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Cash consideration			1,310,000
Net Deferred Tax Liability Excluding Valuation Allowance [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Deferred tax liability			145,200
Deferred Tax Asset Net of Valuation Allowance [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Deferred tax liability			(62,400)
Valuation Allowance of Deferred Tax Assets [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Deferred tax liability			90,000
Loss Carryforwards [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Deferred tax liability			(85,800)
Valuation Allowance, Operating Loss Carryforwards [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Deferred tax liability			66,800
Operating Expense [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					50,200
Interest expense | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					$ 14,500
Insurance Segment [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Goodwill, acquired during period	[2]		466,100
Reinsurance Segment [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Goodwill, acquired during period	[2]		$ 327,900
[1]	Excluded from the table are certain credit facilities under which the Company is permitted to utilize up to $1.4 billion and $1.6 billion as of December 31, 2015 and December 31, 2014, respectively, for revolving loans to support general operating and financing needs. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, were utilized under these facilities to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available to support other operating and financing need
[2]	Includes an increase of $15.9 million to goodwill from the amount initially recorded at June 30, 2015, as a result of several tax-related adjustments, including a decrease in other assets of $7.5 million, a decrease in deferred tax liability of $11.3 million, and an increase in other liabilities of $19.8 million.

Acquisitions and Disposals - 66

Acquisitions and Disposals - Catlin Acquisition consideration (Details) £ / shares in Units, $ / shares in Units, £ in Thousands, $ in Thousands	May. 01, 2015USD ($)shares$ / shares		May. 01, 2015GBP (£)shares£ / shares
Business Acquisition [Line Items]
Closing price per XL share on April 30, 2015 | $ / shares	$ 37.08	[1]
Catlin Group Limited [Member]
Business Acquisition [Line Items]
Catlin Shares outstanding as of April 30, 2015 that received share consideration (including the dilutive effect of warrants)	384,118,000
Exchange ratio per the Implementation Agreement	0.13		0.13
XL Share issuance to Catlin shareholders	49,935,000		49,935,000
XL Share issuance consideration | $	$ 1,851,601
Cash price component, per Catlin Share in GBP | £ / shares			£ 3.88
Cash consideration	$ 2,287,579		£ 1,490,377
Foreign exchange rate: GBP/USD on April 30, 2015	1.5349
Acquisition consideration | $	$ 4,139,180
[1]	The closing market price of XL Shares on the Acquisition Date represents the fair value of XL shares issued as part of the Acquisition Consideration.

Acquisitions and Disposals - Fa

Acquisitions and Disposals - Fair Value of Assets and Liabilities Acquired - Catlin (Details) - USD ($) $ in Thousands		May. 01, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill, acquired during period			$ 807,381	$ 25,159
Catlin Group Limited [Member]
Business Acquisition [Line Items]
Fixed maturities, at fair value		$ 6,266,489
Short-term investments, at fair value		634,599
Equity investments, at fair value		236,230
Investment in affiliates		216,843
Other investments		386,828
Total investments		7,740,989
Cash and cash equivalents	[1]	1,267,565
Unpaid losses and loss expenses recoverable		1,493,267
Reinsurance balances receivable		299,579
Ceded unearned premiums		1,143,852
Deferred acquisition costs and value of business acquired		679,259
Intangible assets		988,000
Other assets		306,686
Total assets		16,509,081
Unpaid losses and loss expenses		6,933,144
Unearned premiums		3,742,234
Reinsurance balances payable		1,441,749
Notes payable and debt		82,066
Payable for investments purchased		34,149
Deferred tax liability	[2]	82,783
Other liabilities		285,481
Total liabilities		12,601,606
Net assets acquired before non-controlling interest		3,907,475
Non-controlling interest in equity of consolidated subsidiaries		562,285
Net assets acquired		3,345,190
Acquisition consideration		4,139,180
Goodwill, acquired during period	[2]	793,990
Accrued Income Receivable [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Acquired receivables		35,063
Premiums Receivable [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Acquired receivables		2,545,188
Receivable From Investments Sold [Member] | Catlin Group Limited [Member]
Business Acquisition [Line Items]
Acquired receivables		$ 9,633
[1]	Includes Restricted cash
[2]	Includes an increase of $15.9 million to goodwill from the amount initially recorded at June 30, 2015, as a result of several tax-related adjustments, including a decrease in other assets of $7.5 million, a decrease in deferred tax liability of $11.3 million, and an increase in other liabilities of $19.8 million.

Acquisitions and Disposals - Tr

Acquisitions and Disposals - Transaction Related Costs - Catlin (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Costs incurred in 2015	$ 156,368
2015 payments	99,079
Liabilities at December 31, 2015	57,289
Severance related costs
Business Acquisition [Line Items]
Costs incurred in 2015	47,185
2015 payments	31,058
Liabilities at December 31, 2015	16,127
Retention and other compensation costs
Business Acquisition [Line Items]
Costs incurred in 2015	35,310
2015 payments	18,341
Liabilities at December 31, 2015	16,969
Facilities-related costs
Business Acquisition [Line Items]
Costs incurred in 2015	14,744
2015 payments	13,926
Liabilities at December 31, 2015	818
Consulting and other
Business Acquisition [Line Items]
Costs incurred in 2015	59,129
2015 payments	35,754
Liabilities at December 31, 2015	$ 23,375

Acquisitions and Disposals - Fi

Acquisitions and Disposals - Financial Results and Supplemental Pro Forma Financial Information - Catlin (Details) - Catlin Group Limited [Member] - USD ($) $ / shares in Units, $ in Thousands	8 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 2,791,789
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ 103,637
Business Acquisition, Pro Forma Revenue		$ 10,628,915	$ 10,938,216
Business Acquisition, Pro Forma Net Income (Loss)		$ 1,221,497	$ 475,914
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 4.03	$ 1.50
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 3.97	$ 1.48

Acquisitions and Disposals - Sa

Acquisitions and Disposals - Sale of operating affiliate (Details) - ARX Holding Corporation [Member] - USD ($) $ in Millions	Apr. 02, 2015	Apr. 01, 2015
Business Acquisition [Line Items]
Ownership percentage remaining		40.60%
Investments in affiliates		$ 220.2
Disposal Group, Including Discontinued Operation, Consideration		$ 560.6
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 340.4

Acquisitions and Disposals - Im

Acquisitions and Disposals - Impact of Life Retro Arrangements (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Underwriting profit (loss)		$ 587,409		$ 585,907	$ 245,191
Net investment income - Life Funds Withheld Assets		872,370		918,625	957,716
Exchange (gains) losses		(22,504)		37,568	28,243
Other income and expenses	[1]	(13,356)		(6,891)	(5,692)
Net realized and unrealized (gains) losses on derivative instruments		53,123		29,886	7,798
Net income (loss)		1,313,339		268,838	1,136,647
Change in adjustments related to future policy benefit reserves, net of tax		170,688		(400,456)	(44,660)
Change in cumulative translation adjustment - Life Funds Withheld Assets, net of tax		(25,315)		(25,729)	(54,858)
Comprehensive income (loss)		(797,842)		747,801	(783,363)
XL Re Life (SAC) Ltd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Comprehensive income (loss)		0		0
Life Funds Withheld Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net investment income - Life Funds Withheld Assets		187,489		129,575	0
Net realized gains (losses) on investments sold		223,272		5,067	0
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets		(27,734)		(9)	0
OTTI on investments - Life Funds Withheld Assets		(13,357)		(20,587)	0
Net realized and unrealized (gains) losses on derivative instruments		(151,691)		(488,222)	0
Change in net unrealized gains (losses) on investments, net of tax		(421,604)		274,083	$ 0
Life Funds Withheld Assets [Member] | XL Re Life (SAC) Ltd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Underwriting profit (loss)		605	[2]	11,649
Net investment income - Life Funds Withheld Assets		187,489		129,575
Net realized gains (losses) on investments sold		223,272		5,067
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets		(27,734)		(9)
OTTI on investments - Life Funds Withheld Assets		(13,357)		(20,587)
Exchange (gains) losses		4,788		10,099
Other income and expenses		2,280		(1,610)
Net realized and unrealized (gains) losses on derivative instruments		(151,691)		(488,222)
Net income (loss)		225,652		(354,038)
Change in net unrealized gains (losses) on investments, net of tax		(421,604)		274,083
Change in adjustments related to future policy benefit reserves, net of tax		170,688		74,009
Change in cumulative translation adjustment - Life Funds Withheld Assets, net of tax		25,869		17,595
Total changes to other comprehensive income as a result of Life Retro Arrangements		(225,047)		365,687
Comprehensive income (loss)		$ 605		$ 11,649
[1]	Net fee income and other includes operating expenses from the Company's loss prevention consulting services business.
[2]	The underwriting profit of $0.6 million relates to a premium adjustment relating to the GreyCastle Life Retro Arrangements transaction, which was completed on May 30, 2014. Excluding this transaction, the impact to comprehensive income relating to the GreyCastle Life Retro Arrangements was nil for the years ended December 31, 2015 and 2014.

Acquisitions and Disposals - Li

Acquisitions and Disposals - Life Retro Arrangements Narrative (Details) - USD ($) $ in Thousands	May. 30, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Underwriting profit (loss)		$ 587,409		$ 585,907	$ 245,191
Comprehensive income (loss)		(797,842)		747,801	$ (783,363)
XL Re Life (SAC) Ltd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of Subsidiary Stock, Percentage	100.00%
Disposal Group, Including Discontinued Operation, Consideration	$ 570,000
Quota Share Reinsurance Percentage	100.00%
Pro Forma Effect of Sale, After Tax Net Loss				621,300
Comprehensive income (loss)		0		0
Life Funds Withheld Assets [Member] | XL Re Life (SAC) Ltd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Underwriting profit (loss)		605	[1]	11,649
Comprehensive income (loss)		$ 605		$ 11,649
[1]	The underwriting profit of $0.6 million relates to a premium adjustment relating to the GreyCastle Life Retro Arrangements transaction, which was completed on May 30, 2014. Excluding this transaction, the impact to comprehensive income relating to the GreyCastle Life Retro Arrangements was nil for the years ended December 31, 2015 and 2014.

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of assets and liabilities that were accounted for at fair value (Details) - USD ($) $ in Thousands		Dec. 31, 2015		Dec. 31, 2014
ASSETS
Fixed maturities, AFS, at fair value		$ 32,257,589		$ 29,359,034
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value		617,390		256,727
Total investments available for sale		33,753,898		30,484,053
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330		0
Trading Securities		1,296,029		1,171
Collateral and counterparty netting, asset	[1]	(3,087)		(696)
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)		914,629		1,155,016
Collateral and counterparty netting, liability	[1]	(3,087)		(696)
Recurring
ASSETS
Total investments available for sale		33,753,898		30,484,053
Cash equivalents	[2]	1,268,666		1,501,832
Other investments		1,291,726	[3]	894,057
Other assets	[1]	86,227		135,963
Total assets accounted for at fair value		37,797,820		33,150,274
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	463,915		450,831
Financial instruments sold, but not yet purchased	[5]	347		30,406
Other liabilities	[1]	42,408		30,488
Total liabilities accounted for at fair value		506,670		511,725
Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Total investments available for sale		528,581		502,284
Cash equivalents	[2]	437,742		1,103,877
Other investments		0	[3]	0
Other assets	[1]	0		0
Total assets accounted for at fair value		966,840		1,606,621
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]	347		4,737
Other liabilities	[1]	0		0
Total liabilities accounted for at fair value		347		4,737
Recurring | Significant other observable inputs (Level 2)
ASSETS
Total investments available for sale		33,073,039		29,280,719
Cash equivalents	[2]	830,924		397,955
Other investments		1,008,176	[3]	708,974
Other assets	[1]	69,914		122,996
Total assets accounted for at fair value		36,378,839		30,644,553
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	463,915		450,831
Financial instruments sold, but not yet purchased	[5]	0		25,669
Other liabilities	[1]	16,304		7,757
Total liabilities accounted for at fair value		480,219		484,257
Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Total investments available for sale		152,278		701,050
Cash equivalents	[2]	0		0
Other investments		283,550	[3]	185,083
Other assets	[1]	19,400		13,663
Total assets accounted for at fair value		455,228		899,796
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]	0		0
Other liabilities	[1]	29,191		23,427
Total liabilities accounted for at fair value		29,191		23,427
Exclude Life Funds Withheld Assets [Member]
ASSETS
Fixed maturities, AFS, at fair value		29,104,486		24,177,469
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value		617,390		256,727
Total investments available for sale		30,600,795		25,302,488
Exclude Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,065,637		2,171,953
Exclude Life Funds Withheld Assets [Member] | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,757,971		3,728,576
Exclude Life Funds Withheld Assets [Member] | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,410		692,034
Exclude Life Funds Withheld Assets [Member] | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,168,572		1,065,293
Exclude Life Funds Withheld Assets [Member] | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring
ASSETS
Fixed maturities, AFS, at fair value		29,104,486		24,177,469
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value	[6]	617,390		256,727
Total investments available for sale		30,600,795		25,302,488
Exclude Life Funds Withheld Assets [Member] | Recurring | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,065,637		2,171,953
Exclude Life Funds Withheld Assets [Member] | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,757,971		3,728,576
Exclude Life Funds Withheld Assets [Member] | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Recurring | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,410		692,034
Exclude Life Funds Withheld Assets [Member] | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,168,572		1,065,293
Exclude Life Funds Withheld Assets [Member] | Recurring | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Recurring | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Equity securities, AFS, at fair value		528,581		502,284
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		528,581		502,284
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		28,952,208		23,476,419
Equity securities, AFS, at fair value		350,338		366,008
Short-term investments, at fair value	[6]	617,390		256,727
Total investments available for sale		29,919,936		24,099,154
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,020,574		2,171,953
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,754,894		3,726,666
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		2		4,076
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,150,715		1,060,005
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Fixed maturities, AFS, at fair value		152,278		701,050
Equity securities, AFS, at fair value		0		0
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		152,278		701,050
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		45,063		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,077		1,910
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,408		687,958
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		17,857		5,288
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Life Funds Withheld Assets [Member]
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699
Short-term investments, at fair value		60,330
Trading Securities		1,296,029		1,171
Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330
Trading Securities		1,296,029
Cash equivalents		101,274		133,198	[2]
Life Funds Withheld Assets [Member] | Recurring | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Recurring | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Short-term investments, at fair value		0
Trading Securities		0
Cash equivalents		517		460	[2]
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330
Trading Securities		1,296,029
Cash equivalents		100,757		132,738	[2]
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Short-term investments, at fair value		0
Trading Securities		0
Cash equivalents		0		0	[2]
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0	[5]
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,561,909		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,561,909		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,508,224		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		53,685		0
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,447		6,016,457
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,447		6,016,457
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,259		6,010,563
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		188		5,894
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		$ 0		$ 0
[1]	Other assets and other liabilities include derivative instruments. The derivative balances included in each category are reported on a gross basis by level with a netting adjustment presented separately in the Collateral and Counterparty Netting column. The fair values of the individual derivative contracts are reported gross in their respective levels based on the fair value hierarchy. For further details regarding derivative fair values and associated collateral received or paid see
[2]	Cash equivalents balances subject to fair value measurement include certificates of deposit and money market funds. Operating cash balances are not subject to recurring fair value measurement guidance.
[3]	The Other investments balance excludes certain structured transactions including certain investments in project finance transactions, a payment obligation and liquidity financing provided to a structured credit vehicle as a part of a third party medium term note facility. These investments, which totaled $141.3 million at December 31, 2015 and $354.4 million at December 31, 2014, are carried at amortized cost. For further information, see Note 8, "Other Investments.
[4]	Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) include balances related to the life retrocession embedded derivative, under which all investment results associated with the Life Funds Withheld Assets related the GreyCastle Life Retro Arrangements described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary", accrue to the benefit of GCLR.
[5]	Financial instruments sold, but not yet purchased, represent "short sales" and are included within "Payable for investments purchased" on the balance sheets.
[6]	Short-term investments consist primarily of Corporate securities and U.S. and Non-U.S. Government and Government-Related/ Supported securities.

Fair Value Measurements - Addit

Fair Value Measurements - Additional information about assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
RMBS - Agency
Level 3 assets
Balance, beginning of period	$ 1,910	$ 10,473
Realized gains (losses)	0	5
Movement in unrealized gains (losses)	(3)	(18)
Purchases and issuances	1,297	120
Sales	0	0
Settlements	(323)	(3,205)
Transfers into Level 3	3,059	0
Transfers out of Level 3	(2,863)	(5,465)
Fixed maturities to short term investments classification change	0	0
Balance, end of period	3,077	1,910
Movement in total gains (losses) above relating to instruments still held at the reporting date	(2)	(12)
U.S. Government and Government - Related/Supported [Member]
Level 3 assets
Balance, beginning of period	0	0
Realized gains (losses)	0	0
Movement in unrealized gains (losses)	0	0
Purchases and issuances	35,044	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	10,019	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	45,063	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	0	0
RMBS - Non-Agency
Level 3 assets
Balance, beginning of period	0	9
Realized gains (losses)	0	1
Movement in unrealized gains (losses)	0	1
Purchases and issuances	0	0
Sales	0	0
Settlements	0	(11)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	0	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	0	0
CMBS
Level 3 assets
Balance, beginning of period	0	12,533
Realized gains (losses)	0	3
Movement in unrealized gains (losses)	0	(3)
Purchases and issuances	0	1,376
Sales	0	0
Settlements	0	(12,533)
Transfers into Level 3	0	0
Transfers out of Level 3	0	(1,376)
Fixed maturities to short term investments classification change	0	0
Balance, end of period	0	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	0	0
Collateralized debt obligations ('CDO') [Member]
Level 3 assets
Balance, beginning of period	687,958	710,253
Realized gains (losses)	(8,658)	3,781
Movement in unrealized gains (losses)	16,688	11,604
Purchases and issuances	25,882	185,710
Sales	(366,633)	(48,313)
Settlements	(322,829)	(175,077)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	32,408	687,958
Movement in total gains (losses) above relating to instruments still held at the reporting date	5,279	14,432
Other asset-backed securities
Level 3 assets
Balance, beginning of period	5,288	11,877
Realized gains (losses)	628	(7)
Movement in unrealized gains (losses)	(599)	65
Purchases and issuances	46,940	5,182
Sales	(7,269)	0
Settlements	(6,359)	(5,705)
Transfers into Level 3	13,317	0
Transfers out of Level 3	(34,089)	(6,124)
Fixed maturities to short term investments classification change	0	0
Balance, end of period	17,857	5,288
Movement in total gains (losses) above relating to instruments still held at the reporting date	451	57
Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Level 3 assets
Balance, beginning of period	0	0
Realized gains (losses)	0	0
Movement in unrealized gains (losses)	0	0
Purchases and issuances	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	0	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	0	0
Short-term investments
Level 3 assets
Balance, beginning of period	0	2,015
Realized gains (losses)	0	0
Movement in unrealized gains (losses)	0	(15)
Purchases and issuances	0	0
Sales	0	0
Settlements	0	(2,000)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	0	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	0	0
Other investments
Level 3 assets
Balance, beginning of period	185,083	113,472
Realized gains (losses)	15,270	12,676
Movement in unrealized gains (losses)	(12,548)	538
Purchases and issuances	117,143	59,401
Sales	(1,417)	0
Settlements	(19,981)	(25,498)
Transfers into Level 3	0	24,494
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	283,550	185,083
Movement in total gains (losses) above relating to instruments still held at the reporting date	2,724	13,212
Derivative Contracts - Net
Level 3 liabilities
Balance, beginning of period	(9,764)	(29,110)
Realized gains (losses)	0	0
Movement in unrealized gains (losses)	(27)	19,346
Purchases and issuances	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	(9,791)	(9,764)
Movement in total gains (losses) above relating to instruments still held at the reporting date	80	19,346
Financial Services Sector [Member] | Corporate
Level 3 assets
Balance, beginning of period	0	0
Realized gains (losses)	9	0
Movement in unrealized gains (losses)	(10)	0
Purchases and issuances	53,686	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fixed maturities to short term investments classification change	0	0
Balance, end of period	53,685	0
Movement in total gains (losses) above relating to instruments still held at the reporting date	(2)	0
Non-Financial Services Sector [Member] | Corporate
Level 3 assets
Balance, beginning of period	5,894	31,573
Realized gains (losses)	(186)	199
Movement in unrealized gains (losses)	(13)	(128)
Purchases and issuances	(123)	3,759
Sales	0	0
Settlements	(316)	(6,543)
Transfers into Level 3	0	766
Transfers out of Level 3	(5,068)	(23,732)
Fixed maturities to short term investments classification change	0	0
Balance, end of period	188	5,894
Movement in total gains (losses) above relating to instruments still held at the reporting date	$ (153)	$ 60

Fair Value Measurements - Finan

Fair Value Measurements - Financial instruments not carried at fair value (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deposit Liabilities		$ 1,168,376	$ 1,245,367
Notes payable and debt	[1]	2,644,970	1,662,580
Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Financial Assets		141,329	354,382
Deposit Liabilities		1,168,376	1,245,367
Notes payable and debt		2,644,970	1,662,580
Financial Liabilities		3,813,346	2,907,947
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Financial Assets		154,065	371,625
Deposit Liabilities		1,436,210	1,543,761
Notes payable and debt		2,805,152	1,897,854
Financial Liabilities		$ 4,241,362	$ 3,441,615
[1]	"In Use/Outstanding" data represent December 31, 2015 and December 31, 2014 accreted values.

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Spread on US Treasury rate for determining discount rate for fair value of deposit liabilities	26.50%	29.50%
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments - structured transactions	$ 141.3	$ 354.4

Segment Information - Statement

Segment Information - Statement of earnings by segment (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Segment Reporting Information [Line Items]
Gross premiums written										$ 10,978,925		$ 8,094,926		$ 7,741,135
Net premiums written										7,951,063		5,944,841		6,199,404
Net premiums earned										8,226,425		5,895,070		6,309,521
Net losses and loss expenses										4,882,197	[1]	3,501,356		4,197,166
Acquisition costs										1,317,448	[1]	738,118		909,323
Operating expenses	[2]									1,439,371		1,069,689		957,841
Underwriting profit (loss)										587,409		585,907		245,191
Net investment income	[3]													885,789
Net results from structured products										17,991	[4]	54,209	[5]	23,791	[6]
Net fee income and other	[7]									(13,356)		(6,891)		(5,692)
Loss on sale of life reinsurance subsidiary										0		666,423		0
Extinguishment of debt										5,592		0		0
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments										202,178		107,462		87,777
Net realized and unrealized (gains) losses on derivative instruments										53,123		29,886		7,798
Net income (loss) from investment fund affiliates and operating affiliates										118,060		203,034		258,195
Gain on sale of operating affiliate										340,407		0		0
Exchange (gains) losses										22,504		(37,568)		(28,243)
Corporate operating expenses										480,755		220,165		209,454
Contribution from P&C and Corporate and Other										1,457,199		486,956		1,321,638
Interest expense										163,021		121,221	[8]	107,486	[8]
Non-controlling interests										106,187		80,498		76,731
Provision (benefit) for income tax										(19,161)		96,897		77,505
Net income (loss) attributable to ordinary shareholders										1,207,152		188,340		1,059,916
Exclude Life Funds Withheld Assets [Member]
Segment Reporting Information [Line Items]
Net investment income	[3]									624,440		721,016
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments										19,997		122,991
Life Funds Withheld Assets [Member]
Segment Reporting Information [Line Items]
Net investment income										187,489		129,575
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments										182,181		(15,529)
Net realized and unrealized (gains) losses on derivative instruments										(151,691)		(488,222)		0
Corporate and other
Segment Reporting Information [Line Items]
Gross premiums written	[9]									309,916		333,436		324,343
Net premiums written	[9]									62,239		177,632		295,422
Net premiums earned	[9]									62,241		177,632		295,422
Net losses and loss expenses	[9]									115,997	[1]	242,963		465,702
Acquisition costs	[9]									10,794	[1]	14,115		26,665
Operating expenses	[2],[9]									1,232		10,693		8,926
Underwriting profit (loss)	[9]									(65,782)		(90,139)		(205,871)
Net investment income	[3],[9]													286,645
Net results from structured products	[9]									0	[4]	0	[5]	0	[6]
Net fee income and other	[7],[9]									622		360		1,305
Loss on sale of life reinsurance subsidiary	[9]											666,423
Extinguishment of debt	[9]									5,592
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments	[9]													1,985
Net realized and unrealized (gains) losses on derivative instruments	[9]									53,123		29,886		7,798
Net income (loss) from investment fund affiliates and operating affiliates	[9]									118,060		203,034		258,195
Gain on sale of operating affiliate										340,407
Exchange (gains) losses	[9]									22,504		(37,568)		(28,243)
Corporate operating expenses	[9]									480,755		220,165		209,454
Contribution from P&C and Corporate and Other	[9]									201,538		(929,872)		168,846
Interest expense	[8],[9]									163,021		121,221		107,486
Non-controlling interests	[9]									106,187		80,498		76,731
Provision (benefit) for income tax	[9]									(19,161)		96,897		77,505
Corporate and other | Exclude Life Funds Withheld Assets [Member]
Segment Reporting Information [Line Items]
Net investment income	[3],[9]									40,569		146,558
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments	[9]									5,411		3,625
Corporate and other | Life Funds Withheld Assets [Member]
Segment Reporting Information [Line Items]
Net investment income										187,489	[9]	129,575
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments	[9]									182,181		(15,529)
Net realized and unrealized (gains) losses on derivative instruments	[9]									(151,691)		(488,222)
Operating Segments [Member] | Total P And C Segment [Member]
Segment Reporting Information [Line Items]
Gross premiums written										10,669,009		7,761,490		7,416,792
Net premiums written										7,888,824		5,767,209		5,903,982
Net premiums earned		$ 2,375,155	$ 2,405,740	$ 2,063,795	$ 1,319,494	$ 1,413,161	$ 1,453,673	$ 1,438,076	$ 1,412,528	8,164,184		5,717,438		6,014,099
Net losses and loss expenses										4,766,200	[1]	3,258,393		3,731,464
Acquisition costs										1,306,654	[1]	724,003		882,658
Operating expenses	[2]									1,438,139		1,058,996		948,915
Underwriting profit (loss)		$ 183,458	$ 114,118	$ 208,779	$ 146,836	$ 218,850	$ 144,375	$ 167,947	$ 144,874	653,191		676,046		451,062
Net investment income	[3]													599,144
Net results from structured products										17,991	[4]	54,209	[5]	23,791	[6]
Net fee income and other	[7]									(13,978)		(7,251)		(6,997)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments														85,792
Net realized and unrealized (gains) losses on derivative instruments										0				0
Contribution from P&C and Corporate and Other										$ 1,255,661		$ 1,416,828		$ 1,152,792
Ratios - P&C operations:
Loss and loss expense ratio	[10]									58.40%		57.00%		62.00%
Underwriting expense ratio	[10]									33.60%		31.20%		30.50%
Combined ratio	[10]									92.00%		88.20%		92.50%
Operating Segments [Member] | Total P And C Segment [Member] | Exclude Life Funds Withheld Assets [Member]
Segment Reporting Information [Line Items]
Net investment income	[3]									$ 583,871		$ 574,458
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments										14,586		119,366
Operating Segments [Member] | Insurance Segment [Member]
Segment Reporting Information [Line Items]
Gross premiums written										8,395,846		5,976,011		$ 5,523,181
Net premiums written										5,859,934		4,134,151		4,154,093
Net premiums earned										5,648,482		4,026,713		4,267,677
Net losses and loss expenses										3,614,048	[1]	2,543,108		2,829,999
Acquisition costs										704,364	[1]	393,319		529,270
Operating expenses	[2]									1,154,760		865,592		782,677
Underwriting profit (loss)										175,310		224,694		125,731
Net results from structured products										12,185	[4]	43,710	[5]	15,562	[6]
Net fee income and other	[7]									$ (16,936)		$ (10,051)		$ (9,317)
Ratios - P&C operations:
Loss and loss expense ratio	[10]									64.00%		63.20%		66.30%
Underwriting expense ratio	[10]									32.90%		31.20%		30.80%
Combined ratio	[10]									96.90%		94.40%		97.10%
Operating Segments [Member] | Reinsurance Segment [Member]
Segment Reporting Information [Line Items]
Gross premiums written										$ 2,273,163		$ 1,785,479		$ 1,893,611
Net premiums written										2,028,890		1,633,058		1,749,889
Net premiums earned										2,515,702		1,690,725		1,746,422
Net losses and loss expenses										1,152,152	[1]	715,285		901,465
Acquisition costs										602,290	[1]	330,684		353,388
Operating expenses	[2]									283,379		193,404		166,238
Underwriting profit (loss)										477,881		451,352		325,331
Net results from structured products										5,806	[4]	10,499	[5]	8,229	[6]
Net fee income and other	[7]									$ 2,958		$ 2,800		$ 2,320
Ratios - P&C operations:
Loss and loss expense ratio	[10]									45.80%		42.30%		51.60%
Underwriting expense ratio	[10]									35.20%		31.00%		29.80%
Combined ratio	[10]									81.00%		73.30%		81.40%
[1]	The Company has reflected the amortization of certain fair value adjustments recorded in conjunction with the Catlin Acquisition within the respective segments.
[2]	Operating expenses of the segments exclude Corporate operating expenses, shown separately.
[3]	Net investment income - excluding Life Funds Withheld Assets does not include net investment income related to the net results from structured products.
[4]	The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million, respectively.
[5]	The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million, respectively.
[6]	The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million, respectively.
[7]	Net fee income and other includes operating expenses from the Company's loss prevention consulting services business.
[8]	Interest expense excludes interest expense related to deposit liabilities recorded in the Insurance and Reinsurance segments.
[9]	Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations.
[10]	Ratios are based on net premiums earned from P&C operations.

Segment Information - Net premi

Segment Information - Net premiums earned by line of business (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
P&C Operations:
P&C Operations										$ 8,164,184	$ 5,717,438	$ 6,014,099
Corporate and Other:
Life Operations										62,241	177,632	295,422
Net amount, premiums earned										8,226,425	5,895,070	6,309,521
Annuity
Corporate and Other:
Life Operations										1	53,363	122,715
Life Insurance Product Line [Member]
Corporate and Other:
Life Operations										62,240	124,269	172,707
Total P And C Segment [Member] | Professional
P&C Operations:
P&C Operations										1,331,669	1,256,643	1,576,365
Total P And C Segment [Member] | Casualty
P&C Operations:
P&C Operations										2,154,034	1,722,907	1,702,007
Total P And C Segment [Member] | Property catastrophe
P&C Operations:
P&C Operations										663,958	433,602	492,568
Total P And C Segment [Member] | Property
P&C Operations:
P&C Operations										1,890,323	1,100,439	1,105,383
Total P And C Segment [Member] | Specialty
P&C Operations:
P&C Operations										1,601,726	833,026	826,839
Total P And C Segment [Member] | Other
P&C Operations:
P&C Operations	[1]									522,474	370,821	310,937
Corporate and other
Corporate and Other:
Life Operations										62,241	177,632	295,422
Net amount, premiums earned	[2]									62,241	177,632	295,422
Corporate and other | Annuity
Corporate and Other:
Life Operations										1	53,363	122,715
Corporate and other | Life Insurance Product Line [Member]
Corporate and Other:
Life Operations										62,240	124,269	172,707
Operating Segments [Member] | Total P And C Segment [Member]
Corporate and Other:
Net amount, premiums earned		$ 2,375,155	$ 2,405,740	$ 2,063,795	$ 1,319,494	$ 1,413,161	$ 1,453,673	$ 1,438,076	$ 1,412,528	8,164,184	5,717,438	6,014,099
Operating Segments [Member] | Insurance Segment [Member]
P&C Operations:
P&C Operations										5,648,482	4,026,713	4,267,677
Corporate and Other:
Net amount, premiums earned										5,648,482	4,026,713	4,267,677
Operating Segments [Member] | Insurance Segment [Member] | Professional
P&C Operations:
P&C Operations										1,163,302	1,075,420	1,370,196
Operating Segments [Member] | Insurance Segment [Member] | Casualty
P&C Operations:
P&C Operations										1,685,748	1,422,684	1,389,851
Operating Segments [Member] | Insurance Segment [Member] | Property catastrophe
P&C Operations:
P&C Operations										0	0	0
Operating Segments [Member] | Insurance Segment [Member] | Property
P&C Operations:
P&C Operations										1,021,037	544,856	544,278
Operating Segments [Member] | Insurance Segment [Member] | Specialty
P&C Operations:
P&C Operations										1,473,929	737,281	732,042
Operating Segments [Member] | Insurance Segment [Member] | Other
P&C Operations:
P&C Operations	[1]									304,466	246,472	231,310
Operating Segments [Member] | Reinsurance Segment [Member]
P&C Operations:
P&C Operations										2,515,702	1,690,725	1,746,422
Corporate and Other:
Net amount, premiums earned										2,515,702	1,690,725	1,746,422
Operating Segments [Member] | Reinsurance Segment [Member] | Professional
P&C Operations:
P&C Operations										168,367	181,223	206,169
Operating Segments [Member] | Reinsurance Segment [Member] | Casualty
P&C Operations:
P&C Operations										468,286	300,223	312,156
Operating Segments [Member] | Reinsurance Segment [Member] | Property catastrophe
P&C Operations:
P&C Operations										663,958	433,602	492,568
Operating Segments [Member] | Reinsurance Segment [Member] | Property
P&C Operations:
P&C Operations										869,286	555,583	561,105
Operating Segments [Member] | Reinsurance Segment [Member] | Specialty
P&C Operations:
P&C Operations										127,797	95,745	94,797
Operating Segments [Member] | Reinsurance Segment [Member] | Other
P&C Operations:
P&C Operations	[1]									$ 218,008	$ 124,349	$ 79,627
[1]	Other within the Insurance segment includes: excess and surplus, programs, surety, structured indemnity and certain discontinued lines. Other within the Reinsurance segment includes: whole account contracts, accident and health and other lines.
[2]	Corporate and Other includes other items of our revenue and expenditures that are not evaluated at the segment level for reporting purposes, as well as the Company's Run-Off Life Operations.

Segment Information - Net pre79

Segment Information - Net premiums written by geographical location (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	$ 7,951,063	$ 5,944,841	$ 6,199,404
Life operations
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	62,239	177,632	295,422
Life operations | Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	62,276	91,979	117,948
Life operations | Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	(37)	85,653	177,474
Operating Segments [Member] | Total P And C Segment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	7,888,824	5,767,209	5,903,982
Operating Segments [Member] | Total P And C Segment [Member] | Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	781,618	636,109	658,041
Operating Segments [Member] | Total P And C Segment [Member] | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	3,045,031	2,528,196	2,650,916
Operating Segments [Member] | Total P And C Segment [Member] | Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	3,628,258	2,124,117	2,111,065
Operating Segments [Member] | Total P And C Segment [Member] | Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Net premiums written	$ 433,917	$ 478,787	$ 483,960

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)segments		Dec. 31, 2014USD ($)		Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments | segments	2
Net results from structured products	$ 17,991	[1]	$ 54,209	[2]	$ 23,791	[3]
Total P And C Segment [Member] | Net Investment Income [Member]
Segment Reporting Information [Line Items]
Net results from structured products	60,400		68,000		71,900
Total P And C Segment [Member] | Interest expense
Segment Reporting Information [Line Items]
Net results from structured products	$ (42,200)		$ (12,900)		$ (48,000)
[1]	The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million, respectively.
[2]	The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million, respectively.
[3]	The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million, respectively.

Investments - Cost (amortized c

Investments - Cost (amortized cost for fixed maturities and short-term investments), fair value, gross unrealized gains, gross unrealized (losses), and OTTI recorded in AOCI (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		$ 31,517,654	$ 27,728,771
Fixed maturities, AFS, at fair value		32,257,589	29,359,034
Amortized cost of short-term investments, available for sale		618,851	257,221
Short-term investments, at fair value		617,390	256,727
Cost of equity securities, available for sale		834,079	763,833
Equity securities, AFS, at fair value		878,919	868,292
Amortized cost		32,970,584	28,749,825
Gross unrealized gains		1,153,289	1,947,804
Gross unrealized losses		(369,975)	(213,576)
Fair value		33,753,898	30,484,053
Non credit-related OTTI	[1]	(57,734)	(76,720)
Exclude Life Funds Withheld Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		28,839,622	23,427,432
Gross unrealized gains, fixed maturities		587,258	936,840
Gross unrealized losses, fixed maturities		(322,394)	(186,803)
Fixed maturities, AFS, at fair value		29,104,486	24,177,469
Amortized cost of short-term investments, available for sale		618,851	257,221
Gross unrealized gains, short term investments		967	49
Gross unrealized losses, short term investments		(2,428)	(543)
Short-term investments, at fair value		617,390	256,727
Cost of equity securities, available for sale		834,079	763,833
Gross unrealized gains, equities		89,993	130,689
Gross unrealized losses, equities		(45,153)	(26,230)
Equity securities, AFS, at fair value		878,919	868,292
Amortized cost		30,292,552	24,448,486
Gross unrealized gains		678,218	1,067,578
Gross unrealized losses		(369,975)	(213,576)
Fair value		30,600,795	25,302,488
Non credit-related OTTI	[1]	(57,734)	(76,720)
Exclude Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		5,047,621	2,100,851
Gross unrealized gains, fixed maturities		52,355	77,889
Gross unrealized losses, fixed maturities		(34,339)	(6,787)
Fixed maturities, AFS, at fair value		5,065,637	2,171,953
Non credit-related OTTI	[1]	0	0
Exclude Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		3,697,756	3,625,171
Gross unrealized gains, fixed maturities		77,776	114,188
Gross unrealized losses, fixed maturities		(17,561)	(10,783)
Fixed maturities, AFS, at fair value		3,757,971	3,728,576
Non credit-related OTTI	[1]	0	0
Exclude Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		319,876	404,398
Gross unrealized gains, fixed maturities		25,644	41,108
Gross unrealized losses, fixed maturities		(16,980)	(18,155)
Fixed maturities, AFS, at fair value		328,540	427,351
Non credit-related OTTI	[1]	(54,200)	(67,918)
Exclude Life Funds Withheld Assets [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		401,713	1,033,819
Gross unrealized gains, fixed maturities		7,933	23,987
Gross unrealized losses, fixed maturities		(4,330)	(5,262)
Fixed maturities, AFS, at fair value		405,316	1,052,544
Non credit-related OTTI	[1]	(1,182)	(2,033)
Exclude Life Funds Withheld Assets [Member] | Collateralized debt obligations ('CDO') [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		41,679	717,544
Gross unrealized gains, fixed maturities		4	1,659
Gross unrealized losses, fixed maturities		(9,273)	(27,169)
Fixed maturities, AFS, at fair value		32,410	692,034
Non credit-related OTTI	[1]	(1,208)	(1,663)
Exclude Life Funds Withheld Assets [Member] | Other asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		1,164,426	1,028,528
Gross unrealized gains, fixed maturities		17,665	42,810
Gross unrealized losses, fixed maturities		(13,519)	(6,045)
Fixed maturities, AFS, at fair value		1,168,572	1,065,293
Non credit-related OTTI	[1]	(1,144)	(1,797)
Exclude Life Funds Withheld Assets [Member] | U.S. States and political subdivisions of the States [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		2,514,048	1,892,566
Gross unrealized gains, fixed maturities		125,395	129,910
Gross unrealized losses, fixed maturities		(7,373)	(1,204)
Fixed maturities, AFS, at fair value		2,632,070	2,021,272
Non credit-related OTTI	[1]	0	0
Exclude Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		5,249,148	4,162,425
Gross unrealized gains, fixed maturities		100,383	139,484
Gross unrealized losses, fixed maturities		(97,917)	(61,836)
Fixed maturities, AFS, at fair value		5,251,614	4,240,073
Non credit-related OTTI	[1]	0	0
Exclude Life Funds Withheld Assets [Member] | Financial Services Sector [Member] | Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		3,535,830	2,687,797
Gross unrealized gains, fixed maturities		49,535	87,058
Gross unrealized losses, fixed maturities		(23,456)	(12,939)
Fixed maturities, AFS, at fair value		3,561,909	2,761,916
Non credit-related OTTI	[1]	0	0
Exclude Life Funds Withheld Assets [Member] | Non-Financial Services Sector [Member] | Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		6,867,525	5,774,333
Gross unrealized gains, fixed maturities		130,568	278,747
Gross unrealized losses, fixed maturities		(97,646)	(36,623)
Fixed maturities, AFS, at fair value		6,900,447	6,016,457
Non credit-related OTTI	[1]	0	(3,309)
Life Funds Withheld Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		2,678,032	4,301,339
Gross unrealized gains, fixed maturities		475,071	880,226
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		3,153,103	5,181,565
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		10,721	14,866
Gross unrealized gains, fixed maturities		2,021	3,858
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		12,742	18,724
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		591	3,301
Gross unrealized gains, fixed maturities		161	481
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		752	3,782
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		24,401	71,075
Gross unrealized gains, fixed maturities		2,552	14,260
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		26,953	85,335
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		107,968	168,886
Gross unrealized gains, fixed maturities		14,513	24,281
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		122,481	193,167
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Other asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		132,674	238,168
Gross unrealized gains, fixed maturities		17,121	35,373
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		149,795	273,541
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		737,735	1,397,194
Gross unrealized gains, fixed maturities		195,781	391,842
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		933,516	1,789,036
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Financial Services Sector [Member] | Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		531,016	701,587
Gross unrealized gains, fixed maturities		67,220	99,432
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		598,236	801,019
Non credit-related OTTI	[1]	0	0
Life Funds Withheld Assets [Member] | Non-Financial Services Sector [Member] | Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of fixed maturities, available for sale		1,132,926	1,706,262
Gross unrealized gains, fixed maturities		175,702	310,699
Gross unrealized losses, fixed maturities		0	0
Fixed maturities, AFS, at fair value		1,308,628	2,016,961
Non credit-related OTTI	[1]	$ 0	$ 0
[1]	Represents the non-credit component of OTTI losses, adjusted for subsequent sales of securities. It does not include the change in fair value subsequent to the impairment measurement date.

Investments - Amortized cost an

Investments - Amortized cost and fair value of trading securities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	$ 1,263,609	$ 1,180
Amortized cost of short term investments, trading	60,176	0
Fixed maturities, trading, at fair value	1,235,699	1,171
Short-term investments, at fair value	60,330	0
Total investments trading	1,296,029	1,171
Life Funds Withheld Assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	1,263,609
Amortized cost of short term investments, trading	60,176
Trading Securities, Cost	1,323,785	1,180
Fixed maturities, trading, at fair value	1,235,699
Short-term investments, at fair value	60,330
Total investments trading	1,296,029	1,171
Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	4,957
Fixed maturities, trading, at fair value	4,990
Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	370
Fixed maturities, trading, at fair value	368
Life Funds Withheld Assets [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	4,874
Fixed maturities, trading, at fair value	4,803
Life Funds Withheld Assets [Member] | Other asset-backed securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	26,405
Fixed maturities, trading, at fair value	25,700
Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	373,492
Fixed maturities, trading, at fair value	370,261
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	344,070
Fixed maturities, trading, at fair value	335,956
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized cost of fixed maturities, trading	509,441	1,180
Fixed maturities, trading, at fair value	$ 493,621	$ 1,171

Investments - Contractual matur

Investments - Contractual maturities of income securities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
AFS securities
Amortized cost of Fixed maturities	$ 31,517,654	$ 27,728,771
Fixed maturities, at fair value	32,257,589	29,359,034
Trading Securities [Abstract]
Amortized cost of fixed maturities, trading	1,263,609	1,180
Fixed maturities, trading, at fair value	1,235,699	1,171
Exclude Life Funds Withheld Assets [Member]
AFS securities
Due less than one year, amortized cost	2,106,851	1,972,224
Due less than one year, fair value	2,104,106	1,980,429
Due after 1 through 5 years, amortized cost	14,051,494	8,919,037
Due after 1 through 5 years, fair value	14,143,461	9,113,651
Due after 5 through 10 years, amortized cost	5,680,830	4,232,396
Due after 5 through 10 years, fair value	5,740,954	4,412,569
Due after 10 years, amortized cost	1,374,997	1,494,315
Due after 10 years, fair value	1,423,156	1,705,022
Subtotal - amortized cost	23,214,172	16,617,972
Subtotal - fair value	23,411,677	17,211,671
Mortgage and asset-backed securities - amortized cost	5,625,450	6,809,460
Mortgage and asset-backed securities - fair value	5,692,809	6,965,798
Amortized cost of Fixed maturities	28,839,622	23,427,432
Fixed maturities, at fair value	29,104,486	24,177,469
Life Funds Withheld Assets [Member]
AFS securities
Due less than one year, amortized cost	81,700	117,048
Due less than one year, fair value	92,921	125,326
Due after 1 through 5 years, amortized cost	386,810	638,526
Due after 1 through 5 years, fair value	416,743	685,787
Due after 5 through 10 years, amortized cost	491,621	1,004,698
Due after 5 through 10 years, fair value	558,805	1,165,348
Due after 10 years, amortized cost	1,452,267	2,059,637
Due after 10 years, fair value	1,784,653	2,649,279
Subtotal - amortized cost	2,412,398	3,819,909
Subtotal - fair value	2,853,122	4,625,740
Mortgage and asset-backed securities - amortized cost	265,634	481,430
Mortgage and asset-backed securities - fair value	299,981	555,825
Amortized cost of Fixed maturities	2,678,032	4,301,339
Fixed maturities, at fair value	3,153,103	5,181,565
Trading Securities [Abstract]
Amortized cost of fixed maturities, trading	1,263,609
Fixed maturities, trading, at fair value	1,235,699
Life Funds Withheld Assets [Member] | Cost [Member]
Trading Securities [Abstract]
Trading securities due less than one year	4,573	0
Trading securities due after 1 through 5 years	278,163	0
Trading securities due after 5 through 10 years	280,487	1,180
Trading securities due after 10 years	668,737	0
Trading Securities Debt Maturities And Short Term Investments Fixed Maturities	1,231,960	1,180
Trading Securities Debt Maturities Without Single Maturity Date	31,649	0
Amortized cost of fixed maturities, trading	1,263,609	1,180
Life Funds Withheld Assets [Member] | Fair value [Member]
Trading Securities [Abstract]
Trading securities due less than one year	5,096	0
Trading securities due after 1 through 5 years	272,220	0
Trading securities due after 5 through 10 years	277,920	1,171
Trading securities due after 10 years	649,592	0
Trading Securities Debt Maturities And Short Term Investments Fixed Maturities	1,204,828	1,171
Trading Securities Debt Maturities Without Single Maturity Date	30,871	0
Fixed maturities, trading, at fair value	1,235,699	1,171
RMBS - Agency | Exclude Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	3,697,756	3,625,171
Mortgage and asset-backed securities - fair value	3,757,971	3,728,576
Amortized cost of Fixed maturities	3,697,756	3,625,171
Fixed maturities, at fair value	3,757,971	3,728,576
RMBS - Agency | Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	591	3,301
Mortgage and asset-backed securities - fair value	752	3,782
Amortized cost of Fixed maturities	591	3,301
Fixed maturities, at fair value	752	3,782
Trading Securities [Abstract]
Amortized cost of fixed maturities, trading	370
Fixed maturities, trading, at fair value	368
RMBS - Agency | Life Funds Withheld Assets [Member] | Cost [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	370	0
RMBS - Agency | Life Funds Withheld Assets [Member] | Fair value [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	368	0
RMBS - Non-Agency | Exclude Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	319,876	404,398
Mortgage and asset-backed securities - fair value	328,540	427,351
Amortized cost of Fixed maturities	319,876	404,398
Fixed maturities, at fair value	328,540	427,351
RMBS - Non-Agency | Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	24,401	71,075
Mortgage and asset-backed securities - fair value	26,953	85,335
Amortized cost of Fixed maturities	24,401	71,075
Fixed maturities, at fair value	26,953	85,335
CMBS | Exclude Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	401,713	1,033,819
Mortgage and asset-backed securities - fair value	405,316	1,052,544
Amortized cost of Fixed maturities	401,713	1,033,819
Fixed maturities, at fair value	405,316	1,052,544
CMBS | Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	107,968	168,886
Mortgage and asset-backed securities - fair value	122,481	193,167
Amortized cost of Fixed maturities	107,968	168,886
Fixed maturities, at fair value	122,481	193,167
Trading Securities [Abstract]
Amortized cost of fixed maturities, trading	4,874
Fixed maturities, trading, at fair value	4,803
CMBS | Life Funds Withheld Assets [Member] | Cost [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	4,874	0
CMBS | Life Funds Withheld Assets [Member] | Fair value [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	4,803	0
Collateralized debt obligations ('CDO') [Member] | Exclude Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	41,679	717,544
Mortgage and asset-backed securities - fair value	32,410	692,034
Amortized cost of Fixed maturities	41,679	717,544
Fixed maturities, at fair value	32,410	692,034
Other asset-backed securities | Exclude Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	1,164,426	1,028,528
Mortgage and asset-backed securities - fair value	1,168,572	1,065,293
Amortized cost of Fixed maturities	1,164,426	1,028,528
Fixed maturities, at fair value	1,168,572	1,065,293
Other asset-backed securities | Life Funds Withheld Assets [Member]
AFS securities
Mortgage and asset-backed securities - amortized cost	132,674	238,168
Mortgage and asset-backed securities - fair value	149,795	273,541
Amortized cost of Fixed maturities	132,674	238,168
Fixed maturities, at fair value	149,795	273,541
Trading Securities [Abstract]
Amortized cost of fixed maturities, trading	26,405
Fixed maturities, trading, at fair value	25,700
Other asset-backed securities | Life Funds Withheld Assets [Member] | Cost [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	26,405	0
Other asset-backed securities | Life Funds Withheld Assets [Member] | Fair value [Member]
Trading Securities [Abstract]
Trading Securities Debt Maturities Without Single Maturity Date	$ 25,700	$ 0

Investments - Analysis of conti

Investments - Analysis of continual unrealized loss position (Details) - Exclude Life Funds Withheld Assets [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Corporate | Financial Services Sector [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	$ 1,641,021	$ 387,619
Less than 12 months - gross unrealized losses	(13,280)	(5,858)
Equal to or greater than 12 months - fair value	102,022	105,155
Equal to or greater than 12 months - gross unrealized losses	(10,192)	(7,097)
Corporate | Non-Financial Services Sector [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	3,275,270	949,851
Less than 12 months - gross unrealized losses	(73,069)	(28,023)
Equal to or greater than 12 months - fair value	227,527	319,066
Equal to or greater than 12 months - gross unrealized losses	(24,706)	(8,657)
RMBS - Agency
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	1,065,055	134,535
Less than 12 months - gross unrealized losses	(10,046)	(220)
Equal to or greater than 12 months - fair value	221,211	512,652
Equal to or greater than 12 months - gross unrealized losses	(7,515)	(10,563)
U.S. Government and Government - Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	3,762,869	251,091
Less than 12 months - gross unrealized losses	(29,339)	(1,196)
Equal to or greater than 12 months - fair value	89,113	342,890
Equal to or greater than 12 months - gross unrealized losses	(5,044)	(5,603)
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	19,614	45,378
Less than 12 months - gross unrealized losses	(1,104)	(1,358)
Equal to or greater than 12 months - fair value	180,146	202,700
Equal to or greater than 12 months - gross unrealized losses	(15,876)	(16,797)
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	118,605	78,356
Less than 12 months - gross unrealized losses	(1,561)	(385)
Equal to or greater than 12 months - fair value	78,651	169,065
Equal to or greater than 12 months - gross unrealized losses	(2,769)	(4,877)
Collateralized debt obligations ('CDO') [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	12,311	249,803
Less than 12 months - gross unrealized losses	(516)	(2,666)
Equal to or greater than 12 months - fair value	20,096	414,516
Equal to or greater than 12 months - gross unrealized losses	(8,757)	(24,503)
Other asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	572,671	143,044
Less than 12 months - gross unrealized losses	(5,252)	(2,813)
Equal to or greater than 12 months - fair value	57,563	57,544
Equal to or greater than 12 months - gross unrealized losses	(8,268)	(3,232)
U.S. States and political subdivisions of the States [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	565,055	32,187
Less than 12 months - gross unrealized losses	(6,609)	(210)
Equal to or greater than 12 months - fair value	12,259	63,695
Equal to or greater than 12 months - gross unrealized losses	(765)	(994)
Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	1,921,286	624,346
Less than 12 months - gross unrealized losses	(53,440)	(19,043)
Equal to or greater than 12 months - fair value	474,929	558,422
Equal to or greater than 12 months - gross unrealized losses	(46,714)	(43,251)
Fixed Maturities And Short Term Investments Available For Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	12,953,757	2,896,210
Less than 12 months - gross unrealized losses	(194,216)	(61,772)
Equal to or greater than 12 months - fair value	1,463,517	2,745,705
Equal to or greater than 12 months - gross unrealized losses	(130,606)	(125,574)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Les than 12 months - fair value	356,742	191,193
Less than 12 months - gross unrealized losses	(45,153)	(26,230)
Equal to or greater than 12 months - fair value	0	0
Equal to or greater than 12 months - gross unrealized losses	$ 0	$ 0

Investments - Analysis of net i

Investments - Analysis of net investment income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Investment Income [Line Items]
Equity securities and other investments	$ 28,200	$ 42,252	$ 35,388
Funds withheld	10,835	14,583	12,783
Total gross investment income	952,685	996,374	1,030,446
Investment expenses	(80,315)	(77,749)	(72,730)
Net investment income	872,370	918,625	957,716
Exclude Life Funds Withheld Assets [Member]
Net Investment Income [Line Items]
Fixed maturities, short term investments and cash equivalents	726,161	809,964	982,275
Net investment income	684,881	789,050	957,716
Life Funds Withheld Assets [Member]
Net Investment Income [Line Items]
Fixed maturities, short term investments and cash equivalents	187,489	129,575	0
Net investment income	$ 187,489	$ 129,575	$ 0

Investments - Analysis of net r

Investments - Analysis of net realized gains (losses) and the change in unrealized (losses) gains on investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net realized gains (losses):
OTTI on investments, net of amounts transferred to other comprehensive income	$ (83,000)	$ (35,700)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	202,178	107,462	$ 87,777
Net realized and unrealized (losses) on investment related derivative instruments	(8,616)	20,121	6,367
Net realized (losses) on investments and net realized and unrealized (losses) on investment related derivative instruments	193,562	127,583	94,144
Net change in unrealized gains (losses) on investments	(956,986)	970,715	(957,192)
Total net realized (losses) on investments, net realized and unrealized (losses) on investment related derivative instruments, and net change in unrealized gains (losses) on investments	(763,424)	1,098,298	(863,048)
Fixed maturities | HTM
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	0	(272,540)	(175,817)
Equity securities
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	(59,619)	(32,577)	105,163
Affiliates and other investments
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	(6,072)	35,143	26,636
Exclude Life Funds Withheld Assets [Member]
Net realized gains (losses):
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	19,997	122,991	87,777
Exclude Life Funds Withheld Assets [Member] | Fixed maturities, short term investments and cash equivalents
Net realized gains (losses):
Gross realized gains	187,523	119,817	129,479
Gross realized losses on investments sold	(134,441)	(66,892)	(84,703)
OTTI on investments, net of amounts transferred to other comprehensive income	(54,346)	(12,341)	(16,282)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(1,264)	40,584	28,494
Exclude Life Funds Withheld Assets [Member] | Fixed maturities | AFS
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	(486,140)	360,463	(913,174)
Exclude Life Funds Withheld Assets [Member] | Equity securities
Net realized gains (losses):
Gross realized gains	79,556	96,260	29,402
Gross realized losses on investments sold	(49,223)	(12,270)	(3,185)
OTTI on investments, net of amounts transferred to other comprehensive income	(15,954)	(10,944)	(17)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	14,379	73,046	26,200
Exclude Life Funds Withheld Assets [Member] | Other investments
Net realized gains (losses):
Gross realized gains	39,198	31,830	46,934
Gross realized losses on investments sold	(19,656)	(10,011)	(13,851)
OTTI on investments, net of amounts transferred to other comprehensive income	(12,660)	(12,458)	0
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	6,882	9,361	33,083
Life Funds Withheld Assets [Member]
Net realized gains (losses):
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(27,734)	(9)	0
Life Funds Withheld Assets [Member] | Fixed maturities, short term investments and cash equivalents
Net realized gains (losses):
Gross realized gains	259,798	7,926	0
Gross realized losses on investments sold	(36,526)	(2,859)	0
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(27,734)	(9)	0
OTTI on investments, net of amounts transferred to other comprehensive income	(13,357)	(20,587)	0
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	182,181	(15,529)	0
Life Funds Withheld Assets [Member] | Fixed maturities | AFS
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	$ (405,155)	$ 880,226	$ 0

Investments - Credit loss impai

Investments - Credit loss impairments on fixed income securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
OTTI related to credit losses recognized in earnings
Balance, beginning of period	$ 131,942	$ 174,805
Credit loss impairment recognized in the current period on securities not previously impaired	9,698	3,907
Credit loss impairments previously recognized on securities which matured, paid down, prepaid or were sold during the period	(54,648)	(42,671)
Credit loss impairments previously recognized on securities impaired to fair value during the period	(2,629)	0
Additional credit loss impairments recognized in the current period on securities previously impaired	2,230	4,185
Accretion of credit loss impairments previously recognized due to an increase in cash flows expected to be collected	(13,124)	(8,284)
Balance, end of period	$ 73,469	$ 131,942

Investments - Narrative (Detail

Investments - Narrative (Details) $ in Thousands	May. 01, 2014USD ($)	Dec. 31, 2015USD ($)positions	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Schedule Of Marketable Securities [Line Items]
Cumulative adjustments recorded to value of future policy benefit reserves, amount		$ (170,688)	$ 400,456	$ 44,660
Fixed maturities, AFS, at fair value		32,257,589	29,359,034
Amortized cost of fixed maturities, available for sale		$ 31,517,654	$ 27,728,771
Percentage of fixed income portfolio invested in securities below investment grade		2.00%	3.00%
Percentage of gross unrealized losses relating to securities below investment grade		14.70%	24.90%
Pledged assets, amount		$ 18,300,000	$ 15,200,000
Gross unrealized losses		$ 369,975	213,576
Total number of positions - AFS | positions		8,729
AFS securities in unrealized loss position (number of positions) | positions		3,248
OTTI on investments, net of amounts transferred to other comprehensive income		$ 83,000	35,700
Credit loss impairments previously recognized on securities which matured, paid down, prepaid or were sold during the period		54,648	42,671
Equity securities, AFS, at fair value		878,919	868,292
Cost of equity securities, available for sale		834,079	763,833
Hedge funds
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		4,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		2,000
Corporate
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		19,400	3,700
Fixed Income Funds Member
Schedule Of Marketable Securities [Line Items]
Cost of equity securities, available for sale		100,000
Structured Credit Securities [Member]
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		1,300	4,300
Other Investments [Member]
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		8,700	12,500
Currency losses
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		23,600	4,300
Collateralized debt obligations ('CDO') [Member]
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		8,000
XL Re Life (SAC) Ltd [Member]
Schedule Of Marketable Securities [Line Items]
Held To Maturity Securities Transferred Security Carrying Value	$ 2,800,000
Fixed maturities, held to maturity, gross unrealized gains	424,900
Fixed maturities, held to maturity, gross unrealized losses	0
Unrealized Gains (Losses) on Investments
Schedule Of Marketable Securities [Line Items]
Cumulative adjustments recorded to value of future policy benefit reserves, amount		(170,700)
Unrealized Gains (Losses) on Investments | XL Re Life (SAC) Ltd [Member]
Schedule Of Marketable Securities [Line Items]
Cumulative adjustments recorded to value of future policy benefit reserves, amount	$ 440,500
Exclude Life Funds Withheld Assets [Member]
Schedule Of Marketable Securities [Line Items]
Fixed maturities, AFS, at fair value		29,104,486	24,177,469
Amortized cost of fixed maturities, available for sale		28,839,622	23,427,432
Gross unrealized losses		369,975	213,576
Equity securities, AFS, at fair value		878,919	868,292
Cost of equity securities, available for sale		834,079	763,833
Exclude Life Funds Withheld Assets [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule Of Marketable Securities [Line Items]
Fixed maturities, AFS, at fair value		3,757,971	3,728,576
Amortized cost of fixed maturities, available for sale		3,697,756	3,625,171
Exclude Life Funds Withheld Assets [Member] | Equity securities
Schedule Of Marketable Securities [Line Items]
OTTI on investments, net of amounts transferred to other comprehensive income		15,954	10,944	$ 17
Exclude Life Funds Withheld Assets [Member] | RMBS - Non-Agency
Schedule Of Marketable Securities [Line Items]
Fixed maturities, AFS, at fair value		328,540	427,351
Amortized cost of fixed maturities, available for sale		319,876	404,398
Exclude Life Funds Withheld Assets [Member] | CMBS
Schedule Of Marketable Securities [Line Items]
Fixed maturities, AFS, at fair value		405,316	1,052,544
Amortized cost of fixed maturities, available for sale		401,713	1,033,819
Exclude Life Funds Withheld Assets [Member] | Collateralized debt obligations ('CDO') [Member]
Schedule Of Marketable Securities [Line Items]
Fixed maturities, AFS, at fair value		32,410	692,034
Amortized cost of fixed maturities, available for sale		$ 41,679	$ 717,544

Investments in Affiliates (Deta

Investments in Affiliates (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 1,708,899	$ 1,637,620
Investment fund affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	1,386,837	1,219,138
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 322,062	$ 418,482

Investments in Affiliates - Inv

Investments in Affiliates - Investment Fund Affiliates (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		$ 1,708,899	$ 1,637,620
Equity in net income (loss) in operating affiliates		118,060	203,034	$ 258,195
Investment fund affiliates
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		1,386,837	1,219,138
Equity in net income (loss) in operating affiliates		$ 73,320	$ 95,816
Ownership percentage remaining		5.80%	6.40%
Combined funds/ estimated total net assets	[1]	$ 24,101,796	$ 19,177,932
Investment fund affiliates | Hedge funds
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		1,084,198	1,023,160
Equity in net income (loss) in operating affiliates		$ 42,668	$ 67,037
Ownership percentage remaining		5.20%	5.70%
Combined funds/ estimated total net assets	[1]	$ 20,906,592	$ 18,072,156
Investment fund affiliates | Arbitrage
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		190,016	134,400
Equity in net income (loss) in operating affiliates		$ 612	$ 12,060
Ownership percentage remaining		8.60%	11.00%
Combined funds/ estimated total net assets	[1]	$ 2,202,112	$ 1,224,526
Investment fund affiliates | Directional
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		551,262	536,470
Equity in net income (loss) in operating affiliates		$ 31,012	$ 32,196
Ownership percentage remaining		7.20%	9.20%
Combined funds/ estimated total net assets	[1]	$ 7,643,134	$ 5,865,247
Investment fund affiliates | Event driven
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates	[2]	285,823	300,168
Equity in net income (loss) in operating affiliates	[2]	$ 5,592	$ 21,030
Ownership percentage remaining	[2]	3.00%	3.10%
Combined funds/ estimated total net assets	[1],[2]	$ 9,460,387	$ 9,703,973
Investment fund affiliates | Multi-style
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		57,097	52,122
Equity in net income (loss) in operating affiliates		$ 5,452	$ 1,751
Ownership percentage remaining		3.60%	4.10%
Combined funds/ estimated total net assets	[1]	$ 1,600,959	$ 1,278,410
Investment fund affiliates | Private investment funds
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments, investment fund affiliates		302,639	195,978
Equity in net income (loss) in operating affiliates		$ 30,652	$ 28,779
Ownership percentage remaining		9.50%	17.70%
Combined funds/ estimated total net assets	[1]	$ 3,195,204	$ 1,105,776
[1]	Total estimated net assets are generally as at November 30 for hedge fund affiliates and September 30 for private investment fund affiliates.
[2]	The Company accounts for its investment in certain funds where the ownership percentage is less than three percent using the equity method, where the Company has significant influence over the related investment management company.

Investments in Affiliates - Ope

Investments in Affiliates - Operating Affiliates (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		$ 1,708,899	$ 1,637,620
Equity in net income (loss) in operating affiliates		$ 118,060	203,034		$ 258,195
Privilege Underwriters' Reciprocal Exchange [Member]
Schedule of Equity Method Investments [Line Items]
Surplus Note Term		10 years
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		$ 322,062	418,482
Equity in net income (loss) in operating affiliates		44,740	107,218
Investee summarized data - total assets	[1]	4,989,581	5,530,061
Investee summarized data - total liabilities	[1]	3,389,699	3,792,261
Investee summarized data - total revenue (loss)	[1]	1,053,803	1,655,459
Investee summarized data - net income (loss)	[1]	182,192	628,963
Other strategic operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		251,348	317,216
Equity in net income (loss) in operating affiliates		33,608	50,132
Investee summarized data - total assets	[1]	4,280,976	4,679,395
Investee summarized data - total liabilities	[1]	3,293,873	3,691,173
Investee summarized data - total revenue (loss)	[1]	847,131	1,075,935
Investee summarized data - net income (loss)	[1]	91,701	152,122
Investment manager affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		70,714	101,266	[2]
Equity in net income (loss) in operating affiliates		11,132	57,086	[2]
Investee summarized data - total assets	[1]	708,605	850,666	[2]
Investee summarized data - total liabilities	[1]	95,826	101,088	[2]
Investee summarized data - total revenue (loss)	[1]	206,672	579,524	[2]
Investee summarized data - net income (loss)	[1]	$ 90,491	$ 476,841	[2]
[1]	Total assets and total liabilities reflect balances related to investees still held at December 31, 2015 and 2014, respectively. Total revenue (loss) and net income (loss) reflect activity for the years ended December 31, 2015 and 2014 related to both investees still held at year-end and investees disposed of during the year.
[2]	During the years ended December 31, 2015 and 2014, the Company received distributions from its Investment Manager Affiliates of approximately $25.3 million and $60.3 million, respectively.

Investments in Affiliates - Nar

Investments in Affiliates - Narrative (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)strategy
Schedule of Equity Method Investments [Line Items]
Number of strategies employed | strategy		4
Required notice period for redemption	30 days
Investments in affiliates	$ 1,708,899	$ 1,637,620
Additional investment commitment - other investments	127,600
CATGS I, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 22,100
Ownership percentage remaining	50.00%
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 322,062	418,482
Other strategic operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	251,348	317,216
Investment manager affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	70,714	101,266	[1]
Distributions received from investment manager affiliates	25,300	60,300
Privilege Underwriters, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 102,500
Ownership percentage remaining	9.90%
Cost of operating affiliate interests acquired	$ 77,500
Privilege Group Holdings GP, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage remaining	9.90%
Privilege Underwriters' Reciprocal Exchange [Member]
Schedule of Equity Method Investments [Line Items]
Cost of operating affiliate interests acquired	$ 25,000
Surplus Note Term	10 years
Additional investment commitment - other investments	$ 50,000
Westaim HIIG LP [Member]
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 32,700
Ownership percentage remaining	13.10%
Five Oaks Investment Corp [Member]
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 33,200
Ownership percentage remaining	21.90%
Cost of operating affiliate interests acquired	$ 49,200
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares	3,125
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 15.75
Subject To Redemption Restrictions [Member]
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 382,000	543,000
Funds held in side pockets
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	$ 18,200	$ 22,200
[1]	During the years ended December 31, 2015 and 2014, the Company received distributions from its Investment Manager Affiliates of approximately $25.3 million and $60.3 million, respectively.

Other Investments - Components

Other Investments - Components of other investments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Other Investments [Line Items]
Other investments	$ 1,433,057	$ 1,248,439
Hedge funds
Other Investments [Line Items]
Other investments	544,070	640,847
Arbitrage
Other Investments [Line Items]
Other investments	205,117	179,821
Directional
Other Investments [Line Items]
Other investments	276,277	336,082
Event driven
Other Investments [Line Items]
Other investments	5,427	56,238
Multi-style
Other Investments [Line Items]
Other investments	57,249	68,706
Private investment funds
Other Investments [Line Items]
Other investments	244,576	129,243
Overseas deposits
Other Investments [Line Items]
Other investments	479,187	92,223
Structured transactions
Other Investments [Line Items]
Other investments	138,608	350,563
Other
Other Investments [Line Items]
Other investments	$ 26,616	$ 35,563

Other Investments - Analysis of

Other Investments - Analysis of net realized and unrealized gains on other investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Investments [Line Items]
Net unrealized gains (losses)	$ 227,038	$ 231,278
Net realized gains (losses)	22,111	19,960	$ 35,189
Hedge funds
Other Investments [Line Items]
Net unrealized gains (losses)	188,698	188,674
Net realized gains (losses)	12,769	6,685	30,858
Private investment funds
Other Investments [Line Items]
Net unrealized gains (losses)	38,340	42,604
Net realized gains (losses)	$ 9,342	$ 13,275	$ 4,331

Other Investments - Narrative (

Other Investments - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)strategy
Other Investments [Line Items]
Number of strategies employed | strategy		4
Required notice period for redemption	30 days
Other investments	$ 1,433,057	$ 1,248,439
Aggregate principal amount of payment obligation purchased	150,000
Estimated fair value of payment obligation at date of purchase	$ 128,100
Coupon rate on outstanding payment obligation	3.50%
Term of payment obligation	11 years 6 months
Fair value of difference between estimated fair value and cost of payment obligation	$ 21,900
Payment obligation, fees	2,500
Other than temporary declines recorded on other investments during the period	8,600	12,500
Cost-method Investments, Realized Losses	6,700
Alternative funds | Funds which are subject to lockups and/or gate provisions
Other Investments [Line Items]
Other investments	399,600	425,700
Alternative funds | Funds held in side pockets
Other Investments [Line Items]
Other investments	$ 26,000	24,500
Alternative funds | Funds held in side pockets | Minimum
Other Investments [Line Items]
Side pockets - liquidation period of underlying investments	2 years
Alternative funds | Funds held in side pockets | Maximum
Other Investments [Line Items]
Side pockets - liquidation period of underlying investments	4 years
Cypress Point 1 [Member]
Other Investments [Line Items]
Aggregate face amount of structured transactions purchased	$ 155,000
Carrying amount of structured finance transaction entered into by XLIB		136,000
Cypress Point 2 [Member]
Other Investments [Line Items]
Aggregate face amount of structured transactions purchased	$ 81,900
Carrying amount of structured finance transaction entered into by XLIB		$ 77,800

Goodwill and Other Intangible96

Goodwill and Other Intangible Assets - Analysis of Goodwill and intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, beginning of year	$ 415,936	$ 396,245	$ 392,882
Goodwill, acquired during period	807,381	25,159
Foreign currency translation, goodwill	(9,687)	(5,468)	3,363
Goodwill, end of year	1,213,630	415,936	396,245
Intangible assets with an indefinite life, beginning of year	15,366	15,366	15,366
Indefinite-lived Intangible Assets Acquired	673,000
Foreign currency translation, indefinite-lived intangible assets	(5,507)
Intangible assets with an indefinite life, end of year	682,859	15,366	15,366
Intangible assets with a definite life, beginning of year	16,650	0	279
Finite-lived Intangible Assets Acquired	315,000	18,500
Amortization	(15,517)	(1,850)	(279)
Foreign currency translation, intangible assets with an definite life	(2,356)
Intangible assets with a definite life, end of year	313,777	16,650	0
Goodwill and other intangible assets, beginning of year	447,952	411,611	408,527
Additions	1,795,381	43,659
Foreign currency translation, intangible assets including goodwill	(17,550)
Goodwill and other intangible assets, end of year	$ 2,210,266	$ 447,952	$ 411,611

Goodwill and Other Intangible97

Goodwill and Other Intangible Assets - Estimated future amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2,016	$ 22,350
2,017	19,017
2,018	17,350
2,019	17,350
2,020	17,350
2021-2036	220,360
Total expected amortization expense	$ 313,777	$ 16,650	$ 0	$ 279

Goodwill and Other Intangible98

Goodwill and Other Intangible Assets - Intangible Assets Acquired - Catlin (Details) - USD ($) $ in Thousands	May. 01, 2015	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 673,000
Finite-lived Intangible Assets Acquired		$ 315,000	$ 18,500
Catlin Group Limited [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Indefinite-lived Intangible Assets Acquired	$ 673,000
Finite-lived Intangible Assets Acquired	315,000
Intangible Assets Acquired	988,000
Catlin Group Limited [Member] | Syndicate Capacity [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Indefinite-lived Intangible Assets Acquired	660,000
Catlin Group Limited [Member] | Insurance Licenses [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Indefinite-lived Intangible Assets Acquired	13,000
Catlin Group Limited [Member] | Managing Agent Contracts [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Finite-lived Intangible Assets Acquired	15,000
Finite-Lived Intangible Asset, Useful Life		15 years
Catlin Group Limited [Member] | Distribution Network [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Finite-lived Intangible Assets Acquired	290,000
Finite-Lived Intangible Asset, Useful Life		20 years
Catlin Group Limited [Member] | Trademarks and Trade Names [Member]
Schedule Of Acquired Intangible Assets By Major Class [Line Items]
Finite-lived Intangible Assets Acquired	$ 10,000
Finite-Lived Intangible Asset, Useful Life		2 years

Goodwill and Other Intangible99

Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands		Jul. 24, 2015	May. 01, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross				$ 333,500	$ 18,500
Finite-Lived Intangible Assets, Accumulated Amortization				17,400	1,900
Indefinite-lived Intangible Assets Acquired				673,000
Goodwill				1,213,630	415,936	$ 396,245	$ 392,882
Goodwill, acquired during period				807,381	25,159
Gross goodwill				2,600,000	1,800,000
Accumulated impairment loss on goodwill				1,400,000
Indefinite-Lived Intangible Assets (Excluding Goodwill)				682,859	15,366	$ 15,366	$ 15,366
Insurance Segment [Member]
Goodwill [Line Items]
Goodwill				479,500
Reinsurance Segment [Member]
Goodwill [Line Items]
Goodwill				$ 734,200	$ 415,936
Catlin Group Limited [Member]
Goodwill [Line Items]
Indefinite-lived Intangible Assets Acquired			$ 673,000
Goodwill, acquired during period	[1]		793,990
Catlin Group Limited [Member] | Insurance Segment [Member]
Goodwill [Line Items]
Goodwill, acquired during period	[1]		466,100
Catlin Group Limited [Member] | Reinsurance Segment [Member]
Goodwill [Line Items]
Goodwill, acquired during period	[1]		$ 327,900
New Energy Risk Inc. [Member]
Goodwill [Line Items]
Goodwill, acquired during period		$ 13,400
[1]	Includes an increase of $15.9 million to goodwill from the amount initially recorded at June 30, 2015, as a result of several tax-related adjustments, including a decrease in other assets of $7.5 million, a decrease in deferred tax liability of $11.3 million, and an increase in other liabilities of $19.8 million.

Reinsurance - Effects of Reinsu

Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net premiums written:
Net premiums written	$ 7,951,063	$ 5,944,841	$ 6,199,404
Net premiums earned:
Direct premiums earned	7,717,173	5,173,403	4,966,207
Assumed premiums earned	3,775,337	2,676,765	2,687,603
Ceded premiums earned	(3,266,085)	(1,955,098)	(1,344,289)
Net amount, premiums earned	8,226,425	5,895,070	6,309,521
Total P And C Segment [Member]
Net premiums written:
Direct premiums written	7,847,236	5,450,868	5,050,953
Assumed premiums written	2,821,771	2,310,621	2,365,839
Ceded premiums written	(2,780,183)	(1,994,280)	(1,512,810)
Net premiums written	7,888,824	5,767,209	5,903,982
Net premiums earned:
Direct premiums earned	7,717,173	5,173,403	4,966,207
Assumed premiums earned	3,465,421	2,343,329	2,363,261
Ceded premiums earned	(3,018,410)	(1,799,294)	(1,315,369)
Net amount, premiums earned	$ 8,164,184	$ 5,717,438	$ 6,014,099

Reinsurance - Components of Unp

Reinsurance - Components of Unpaid Losses and Loss Expenses Recoverable (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Analysis of total unpaid losses and loss expenses recoverable by segment:
Unpaid losses and loss expenses recoverable	$ 5,262,706	$ 3,429,368
Total P And C Segment [Member]
Analysis of total unpaid losses and loss expenses recoverable by segment:
Unpaid losses and loss expenses recoverable	5,248,905	3,411,528
Corporate and other
Analysis of total unpaid losses and loss expenses recoverable by segment:
Unpaid losses and loss expenses recoverable	$ 13,801	$ 17,840

Reinsurance - Ceded Credit Risk

Reinsurance - Ceded Credit Risk (Details) - Reinsurance Recoverable [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
A or better rating
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	96.00%	93.00%
Ceded Credit Risk, Concentrated Credit Risk [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	100.00%
Ceded Credit Risk, Concentrated Credit Risk [Member] | AAA
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	3.00%
Ceded Credit Risk, Concentrated Credit Risk [Member] | AA
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	45.80%
Ceded Credit Risk, Concentrated Credit Risk [Member] | AA- | Munich Reinsurance Company
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	26.10%
Ceded Credit Risk, Concentrated Credit Risk [Member] | AA- | Swiss Reinsurance Company
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	6.80%
Ceded Credit Risk, Concentrated Credit Risk [Member] | AA- | Swiss Re Europe S.A.
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	4.90%
Ceded Credit Risk, Concentrated Credit Risk [Member] | A+ | Transatlantic Reinsurance Company [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	4.30%
Ceded Credit Risk, Concentrated Credit Risk [Member] | A+ | Arch Reinsurance Co [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	3.00%
Ceded Credit Risk, Concentrated Credit Risk [Member] | A+ | Lloyds Syndicate
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	11.70%
Ceded Credit Risk, Concentrated Credit Risk [Member] | A
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	47.20%
Ceded Credit Risk, Concentrated Credit Risk [Member] | BBB
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	0.50%
Ceded Credit Risk, Concentrated Credit Risk [Member] | Standard Poors BB And Below Rating [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	0.70%
Ceded Credit Risk, Concentrated Credit Risk [Member] | Captives
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	2.70%
Ceded Credit Risk, Concentrated Credit Risk [Member] | Not Rated NR [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	0.10%
Minimum | Ceded Credit Risk, Concentrated Credit Risk [Member]
Ceded Credit Risk [Line Items]
Maximum percentage of ceded written premium	3.00%

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	$ 3,719,131	$ 4,265,678
Reinsurance recoveries on losses and loss expenses recorded during period	1,600,000	700,000	$ 700,000
Total reinsurance assets	5,700,000	3,600,000
Reinsurance receivable on paid losses	418,666	131,519
Unpaid losses and loss expenses recoverable	5,262,706	3,429,368
Total allowance for uncollectible reinsurance	82,145	64,439
Collateral held related to reinsurance recoverables	3,800,000	2,000,000
Total allowance recorded relating to reinsurance recoverables	58,200	42,300
Total allowance recorded relating to reinsurance balances receivable	23,900	22,100
U.S. Term Life Reinsurance [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	284,481	0
XL Re Life (SAC) Ltd [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	$ 3,719,131	$ 4,265,678

Losses and Loss Expenses - Comp

Losses and Loss Expenses - Components of Loss Reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liability for Claims and Claims Adjustment Expense [Abstract]
Reserve for reported losses and loss expenses	$ 10,293,448	$ 7,461,444
Reserve for losses incurred but not reported	15,146,296	11,891,799
Unpaid losses and loss expenses at end of year	$ 25,439,744	$ 19,353,243	$ 20,481,065	$ 20,484,121

Losses and Loss Expenses - Loss

Losses and Loss Expenses - Loss Reserve Rollforward and Components of Net Losses and Loss Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss expenses incurred	$ 4,766,200	$ 3,258,393	$ 3,731,464
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid losses and loss expenses at beginning of year	19,353,243	20,481,065	20,484,121
Unpaid losses and loss expenses recoverable, beginning of year	3,411,528	3,414,735	3,361,703
Net unpaid losses and loss expenses at beginning of year	15,941,715	17,066,330	17,122,418
Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in:
Current year	5,072,830	3,513,465	4,021,353
Prior year development	(306,630)	(255,072)	(289,889)
Total net incurred losses and loss expenses	4,766,200	3,258,393	3,731,464
Loss and loss expense reserves acquired in business combination	5,439,876	0	0
Exchange rate effects	(582,300)	(561,673)	40,587
Less net losses and loss expenses paid in respect of losses occurring in:
Current year	1,047,277	381,008	425,254
Prior years	4,327,375	3,440,327	3,402,885
Total net paid losses	5,374,652	3,821,335	3,828,139
Net unpaid losses and loss expenses at end of year	20,190,839	15,941,715	17,066,330
Unpaid losses and loss expenses recoverable, end of year	3,411,528	3,414,735	3,361,703	$ 5,248,905
Unpaid losses and loss expenses at end of year	25,439,744	19,353,243	20,481,065
Loss and loss expenses payments
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss expenses incurred	6,505,075	4,499,642	4,496,802
Change in unpaid losses and loss expenses
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss expenses incurred	(168,263)	(514,406)	(71,901)
Change in unpaid losses and loss expenses recoverable
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss expenses incurred	(440,189)	(48,536)	(24,774)
Paid loss recoveries
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net losses and loss expenses incurred	$ (1,130,423)	$ (678,307)	$ (668,663)

Losses and Loss Expenses - Prio

Losses and Loss Expenses - Prior Year Development - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (306,630)	$ (255,072)	$ (289,889)
Insurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(65,030)	(99,758)	(102,039)
Insurance Segment [Member] | Professional
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	5,763	17,097	75,045
Insurance Segment [Member] | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(11,949)	38,414	(21,829)
Insurance Segment [Member] | Property
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	25,189	(57,470)	(46,387)
Insurance Segment [Member] | Specialty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(120,879)	(82,756)	(140,740)
Insurance Segment [Member] | Other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	36,846	(15,043)	31,872
Reinsurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(241,600)	(155,314)	(187,850)
Reinsurance Segment [Member] | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(40,100)	(44,300)	(72,200)
Reinsurance Segment [Member] | Other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(27,800)	(25,700)	21,300
Reinsurance Segment [Member] | Property and other short-tail lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(173,754)	(85,324)	(136,912)
Reinsurance Segment [Member] | Casualty and other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (67,846)	$ (69,990)	$ (50,938)

Losses and Loss Expenses - P107

Losses and Loss Expenses - Prior Year Development - Insurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (306,630)	$ (255,072)	$ (289,889)
Insurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(65,030)	(99,758)	(102,039)
Insurance Segment [Member] | Discontinued Specialty Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(14,800)
Insurance Segment [Member] | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(11,949)	38,414	(21,829)
Insurance Segment [Member] | Excess and surplus casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	31,200
Insurance Segment [Member] | Excess Casualty [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(24,500)
Insurance Segment [Member] | Property
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	25,189	(57,470)	(46,387)
Insurance Segment [Member] | Construction Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	53,100
Insurance Segment [Member] | Professional Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	5,763	17,097	75,045
Insurance Segment [Member] | Specialty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(120,879)	(82,756)	(140,740)
Insurance Segment [Member] | Aerospace [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(15,200)
Insurance Segment [Member] | Marine Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(60,800)
Insurance Segment [Member] | Crisis Management [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(7,100)
Insurance Segment [Member] | Other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	36,846	$ (15,043)	$ 31,872
Insurance Segment [Member] | Excess and Surplus [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	25,400
Insurance Segment [Member] | Surety Product Line [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	18,300
Insurance Segment [Member] | Structured Indemnity
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(10,100)
Insurance Segment [Member] | Bermuda | Political Risk Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(18,800)
Insurance Segment [Member] | International [Member] | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(24,000)
Insurance Segment [Member] | International [Member] | Energy Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (29,600)

Losses and Loss Expenses - P108

Losses and Loss Expenses - Prior Year Development - Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (306,630)	$ (255,072)	$ (289,889)
Reinsurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(241,600)	(155,314)	(187,850)
Reinsurance Segment [Member] | Property and other short-tail lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(173,754)	(85,324)	(136,912)
Reinsurance Segment [Member] | Property catastrophe lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(50,300)	12,400	(60,000)
Reinsurance Segment [Member] | Property other lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(88,900)	(63,400)	(57,300)
Reinsurance Segment [Member] | Marine and aviation lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(34,600)	(34,400)	(19,600)
Reinsurance Segment [Member] | Casualty and other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(67,846)	(69,990)	(50,938)
Reinsurance Segment [Member] | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(40,100)	(44,300)	(72,200)
Reinsurance Segment [Member] | Other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (27,800)	$ (25,700)	$ 21,300

Losses and Loss Expenses - L109

Losses and Loss Expenses - Loss Reserve Discounting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loss And Loss Expenses Disclosure [Line Items]
Unpaid losses and loss expenses	$ 25,439,744	$ 19,353,243	$ 20,481,065	$ 20,484,121
Workers' compensation
Loss And Loss Expenses Disclosure [Line Items]
Discount rate used on unpaid losses for workers compensation	3.75%	5.00%
Undiscounted tabular unpaid losses and loss expenses, net of reinsurance reserve	$ 747,400	$ 515,400
Tabular unpaid losses and loss expenses	$ 445,300	$ 266,400
UK motor liabilities
Loss And Loss Expenses Disclosure [Line Items]
Discount rate used on unpaid losses	2.00%	1.50%
Undiscounted tabular unpaid losses and loss expenses, net of reinsurance reserve	$ 298,100	$ 249,800
Tabular unpaid losses and loss expenses	$ 167,900	$ 161,000

Losses and Loss Expenses - Asbe

Losses and Loss Expenses - Asbestos and Environmental Exposures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of opening and closing unpaid losses and loss expenses related to asbestos and environmental exposure claims:
Net unpaid losses and loss expenses at beginning of year	$ 81,416	$ 80,435	$ 78,315
Net incurred losses and loss expenses	15,663	8,903	6,257
Less net paid losses and loss expenses	9,087	7,922	4,137
Net increase (decrease) in unpaid losses and loss expenses	6,576	981	2,120
Acquired reserves	5,712	0	0
Net unpaid losses and loss expenses at end of year	93,704	81,416	80,435
Unpaid losses and loss expenses recoverable at end of year	93,688	100,537	115,090
Gross unpaid losses and loss expenses at end of year	187,392	181,953	195,525
Reserves for incurred but not reported losses, net of reinsurance	$ 65,100	$ 49,300	$ 48,600

Losses and Loss Expenses - A111

Losses and Loss Expenses - Asbestos and Environmental Exposures Claims Rollforward (Details) - claims	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asbestos claims
Reconciliation of opening and closing unpaid losses and loss expenses related to asbestos and environmental exposure claims:
Total number of claims outstanding, beginning of period	1,399	1,097	1,073
New claims reported	272	456	178
Claims resolved	(246)	(154)	(154)
Asbestos And Environment Claims New Claims Acquired Number	1,166
Total number of claims outstanding, end of period	2,591	1,399	1,097
Environmental claims
Reconciliation of opening and closing unpaid losses and loss expenses related to asbestos and environmental exposure claims:
Total number of claims outstanding, beginning of period	459	338	354
New claims reported	67	190	34
Claims resolved	(96)	(69)	(50)
Asbestos And Environment Claims New Claims Acquired Number	0
Total number of claims outstanding, end of period	430	459	338

Losses and Loss Expenses - A112

Losses and Loss Expenses - Asbestos and Environmental Exposures Discussion (Details) $ in Millions	12 Months Ended
	Dec. 31, 2006USD ($)	Dec. 31, 2015USD ($)claims	Dec. 31, 2014USD ($)claims	Dec. 31, 2013USD ($)claims	Dec. 31, 2012claims
Loss And Loss Expenses Disclosure [Line Items]
Losses acquired through portfolio transfer, amount	$ 40.2
Combined aggregate limit on reserves acquired	60
Reserves for incurred but not reported losses, net of reinsurance		$ 65.1	$ 49.3	$ 48.6
Net asbestos and environmental reserves to total reserves, percentage		1.00%	1.00%
Asbestos and environmental claims
Loss And Loss Expenses Disclosure [Line Items]
Losses acquired through portfolio transfer, amount	$ 18.3
Claim files due to precautionary claim notices, percentage		32.00%	46.00%	37.00%
Environmental claims
Loss And Loss Expenses Disclosure [Line Items]
Total number of claims outstanding | claims		430	459	338	354
Asbestos claims
Loss And Loss Expenses Disclosure [Line Items]
Total number of claims outstanding | claims		2,591	1,399	1,097	1,073

Deposit Liabilities (Details)

Deposit Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Net results from structured products	$ 17,991	[1]	$ 54,209	[2]	$ 23,791	[3]
Deposit liabilities	1,168,376		1,245,367
Accretion expense on deposit liabilities	$ 42,200		12,900		$ 48,000
Interest expense | Structured Indemnity
Net results from structured products			$ 28,700
[1]	The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million, respectively.
[2]	The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million, respectively.
[3]	The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million, respectively.

Future Policy Benefit Reserv114

Future Policy Benefit Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	$ (3,719,131)	$ (4,265,678)
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	914,629	1,155,016
Future policy benefit reserves are comprised of the following:
Traditional life	792,001	789,133
Annuities	3,371,499	3,918,066
Total future policy benefit reserves	$ 4,163,500	$ 4,707,199
Other information:
Average interest rate used for future policy benefits, percent	3.30%	3.30%
XL Re Life (SAC) Ltd [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Funds Held under Reinsurance Agreements, Liability	$ 4,633,760	$ 5,420,694
Reinsurance recoverable from GCLR	(3,719,131)	(4,265,678)
U.S. Term Life Reinsurance [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	(284,481)	0
Other Life Retrocessions [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Reinsurance recoverable from GCLR	(13,801)	(17,840)
Corporate and other | XL Re Life (SAC) Ltd [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future Policy Benefit Reserve Retention	$ 146,087	$ 423,681

Notes Payable and Debt and F115

Notes Payable and Debt and Financing Arrangements - Financing Structure (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Mar. 30, 2015	Dec. 31, 2014	Sep. 15, 2014
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	$ 2,675,000		$ 1,675,000
Notes payable and debt	[2]	2,644,970		1,662,580
Senior notes | 2.3% Senior Notes due 2018
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	300,000		300,000
Notes payable and debt	[2]	$ 298,015		297,344
Debt instrument interest rate, stated percentage		2.30%
Senior notes | 5.75% Senior Notes due 2021
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	$ 400,000		400,000
Notes payable and debt	[2]	$ 397,523		397,092
Debt instrument interest rate, stated percentage		5.75%
Senior notes | 6.375% Senior Notes due 2024
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	$ 350,000		350,000
Notes payable and debt	[2]	$ 349,029		348,920
Debt instrument interest rate, stated percentage		6.375%
Senior notes | 6.25% Senior Notes due 2027
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	$ 325,000		325,000
Notes payable and debt	[2]	$ 323,218		323,062
Debt instrument interest rate, stated percentage		6.25%
Senior notes | 5.25% Senior Notes due 2043
Debt Instrument [Line Items]
Debt instrument, face amount	[1]	$ 300,000		300,000
Notes payable and debt	[2]	$ 296,294		296,162
Debt instrument interest rate, stated percentage		5.25%
Subordinated debt | 4.45% Subordinated Notes due 2025
Debt Instrument [Line Items]
Debt instrument, face amount	[1]		$ 500,000	0
Notes payable and debt	[2]	$ 492,521		0
Debt instrument interest rate, stated percentage		4.45%
Subordinated debt | 5.5% Subordinated Notes due 2045
Debt Instrument [Line Items]
Debt instrument, face amount	[1]		$ 500,000	0
Notes payable and debt	[2]	$ 488,370		0
Debt instrument interest rate, stated percentage		5.50%
XL Cayman [Member] | Senior notes
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage					5.25%
XL Cayman [Member] | Subordinated debt | 4.45% Subordinated Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage			4.45%
XL Cayman [Member] | Subordinated debt | 5.5% Subordinated Notes due 2045
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage			5.50%
Revolving credit facility
Debt Instrument [Line Items]
Available letter of credit facilities - commitments		$ 1,400,000		1,600,000
Available letter of credit facilities - in use		527,100		606,100
Line of credit facility, remaining borrowing capacity		822,900		968,900
Letter of credit facility
Debt Instrument [Line Items]
Available letter of credit facilities - commitments	[3],[4]	4,463,041		3,575,000
Available letter of credit facilities - in use	[4]	$ 2,515,653		$ 1,790,561
[1]	Excluded from the table are certain credit facilities under which the Company is permitted to utilize up to $1.4 billion and $1.6 billion as of December 31, 2015 and December 31, 2014, respectively, for revolving loans to support general operating and financing needs. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, were utilized under these facilities to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available to support other operating and financing need
[2]	"In Use/Outstanding" data represent December 31, 2015 and December 31, 2014 accreted values.
[3]	As of December 31, 2015 and December 31, 2014 the stated portion of allowable credit facilities permitted to be utilized for revolving loans was $1.4 billion and $1.6 billion, respectively. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, of such facilities' limits were utilized to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available either to issue additional letters of credit or to support other operating or financing needs under these particular facilities.
[4]	As of December 31, 2015 and December 31, 2014, there were fifteen and eight available credit facilities, respectively.

Notes Payable and Debt and F116

Notes Payable and Debt and Financing Arrangements - Narrative relating to debt (Details) $ in Thousands, € in Millions		Mar. 30, 2015USD ($)	Sep. 15, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015EUR (€)
Debt Instrument [Line Items]
Percentage ownership of subsidiaries				100.00%	100.00%
Debt instrument, face amount	[1]			$ 2,675,000	$ 1,675,000
Extinguishment of debt				$ 5,592	0	$ 0
Subordinated debt | 4.45% Subordinated Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage				4.45%			4.45%
Debt instrument, face amount	[1]	$ 500,000			0
Subordinated debt | 5.5% Subordinated Notes due 2045
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage				5.50%			5.50%
Debt instrument, face amount	[1]	$ 500,000			$ 0
XL Cayman [Member] | Senior notes
Debt Instrument [Line Items]
Extinguishment of debt			$ 600,000
Debt instrument interest rate, stated percentage			5.25%
XL Cayman [Member] | Subordinated debt | 4.45% Subordinated Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage		4.45%
Debt issuance percentage of face value		99.633%
Proceeds from debt, net of issuance costs		$ 492,200
Debt issuance cost		$ 5,900
XL Cayman [Member] | Subordinated debt | 5.5% Subordinated Notes due 2045
Debt Instrument [Line Items]
Debt instrument interest rate, stated percentage		5.50%
Debt issuance percentage of face value		99.115%
Proceeds from debt, net of issuance costs		$ 488,400
Debt issuance cost		$ 7,200
Catlin Underwriting [Member] | Subordinated debt | Variable Rate Subordinated Notes Face Amount Seven Million Euro [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.95%
Debt instrument, face amount | €							€ 7
Catlin Underwriting [Member] | Subordinated debt | Variable Rate Subordinated Notes Face Amount Twenty Seven Million [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				3.17%
Debt instrument, face amount				$ 27,000
Catlin Underwriting [Member] | Subordinated debt | Variable Rate Subordinated Notes Face Amount Thirty One Million [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				3.10%
Debt instrument, face amount				$ 31,000
Catlin Underwriting [Member] | Subordinated debt | Variable Rate Subordinated Notes Face Amount Ten Million [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				3.00%
Debt instrument, face amount				$ 10,000
Catlin Underwriting [Member] | Subordinated debt | Variable Rate Subordinated Notes Face Amount Eleven Million Euro [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				3.00%
Debt instrument, face amount | €							€ 11
[1]	Excluded from the table are certain credit facilities under which the Company is permitted to utilize up to $1.4 billion and $1.6 billion as of December 31, 2015 and December 31, 2014, respectively, for revolving loans to support general operating and financing needs. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, were utilized under these facilities to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available to support other operating and financing need

Notes Payable and Debt and F117

Notes Payable and Debt and Financing Arrangements - Letter of credit summary (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments	[1],[2]	$ 4,463,041	$ 3,575,000
Available letter of credit facilities - in use	[2]	$ 2,515,653	$ 1,790,561
Collateralized by certain assets of the Company's investment portfolio	[2]	50.90%	66.20%
Revolving credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments		$ 1,400,000	$ 1,600,000
Available letter of credit facilities - in use		$ 527,100	$ 606,100
[1]	As of December 31, 2015 and December 31, 2014 the stated portion of allowable credit facilities permitted to be utilized for revolving loans was $1.4 billion and $1.6 billion, respectively. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, of such facilities' limits were utilized to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available either to issue additional letters of credit or to support other operating or financing needs under these particular facilities.
[2]	As of December 31, 2015 and December 31, 2014, there were fifteen and eight available credit facilities, respectively.

Notes Payable and Debt and F118

Notes Payable and Debt and Financing Arrangements - Narrative relating to credit facilities (Details) $ in Thousands		1 Months Ended
		Nov. 30, 2013USD ($)Credit_Facilities	Dec. 31, 2015USD ($)Credit_Facilities	Dec. 31, 2014USD ($)Credit_Facilities	Dec. 30, 2014USD ($)
Line of Credit Facility [Line Items]
Number of letter of credit facilities available | Credit_Facilities			15	8
Funds at Lloyds Bilateral Facility [Member]
Line of Credit Facility [Line Items]
Number of letter of credit facilities available | Credit_Facilities			4
Available letter of credit facilities - commitments			$ 500,000
Funds at Lloyds Bilateral Facility I [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			125,000
Funds at Lloyds Bilateral Facility II [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			125,000
Funds at Lloyds Bilateral Facility III [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			125,000
Funds at Lloyds Bilateral Facility IV [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			125,000
Two Thousand Thirteen Citi Agreements [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			350,000
Revolving credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			527,100	$ 606,100
Available letter of credit facilities - commitments			1,400,000	1,600,000
Line of credit facility, remaining borrowing capacity			822,900	968,900
Syndicated Credit Agreements [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments		$ 2,000,000
Optional increase capacity			500,000
Number of credit facilities entered into | Credit_Facilities		2
Two Thousand Thirteen Secured Credit Agreement [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			1,000,000
Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use	[1]		2,515,653	1,790,561
Available letter of credit facilities - commitments	[1],[2]		4,463,041	$ 3,575,000
Two Thousand Thirteen Unsecured Credit Agreement [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			1,000,000
Twenty Fifteen Goldman Sachs Facility [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - commitments			200,000
Catlin Bermuda [Member] | Bilateral Facility [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			230,000
Catlin Re Switzerland [Member] | Bilateral Facility [Member]
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			175,000
Catlin Group Limited [Member] | Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			8,000
Citibank Europe plc [Member] | Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			600,000		$ 750,000
ING Bank N.V., London Branch [Member] | Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			$ 150,000
Lloyds Syndicate | Catlin Bermuda [Member] | Bilateral Facility [Member]
Line of Credit Facility [Line Items]
Number of letter of credit facilities available | Credit_Facilities			4
Citibank N.A. [Member] | Letter of credit facility
Line of Credit Facility [Line Items]
Available letter of credit facilities - in use			$ 250,000
[1]	As of December 31, 2015 and December 31, 2014, there were fifteen and eight available credit facilities, respectively.
[2]	As of December 31, 2015 and December 31, 2014 the stated portion of allowable credit facilities permitted to be utilized for revolving loans was $1.4 billion and $1.6 billion, respectively. However, as of December 31, 2015 and December 31, 2014, $527.1 million and $606.1 million, respectively, of such facilities' limits were utilized to issue letters of credit, leaving $822.9 million and $968.9 million, respectively, available either to issue additional letters of credit or to support other operating or financing needs under these particular facilities.

Derivative Instruments - Gross

Derivative Instruments - Gross amounts of derivative fair values contained in the consolidated balance sheet (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Derivatives Fair Value [Line Items]
Asset derivative fair value		$ 89,314	$ 136,659
Liability derivative fair value		45,495	31,184
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Asset derivative notional amount		1,667,585	2,300,609
Asset derivative fair value	[1]	64,289	121,862
Liability derivative notional amount		674,976	302,211
Liability derivative fair value	[1]	11,941	2,936
Designated as Hedging Instrument | Foreign Exchange Contract
Derivatives Fair Value [Line Items]
Asset derivative notional amount		1,667,585	2,300,609
Asset derivative fair value	[1]	64,289	121,862
Liability derivative notional amount		674,976	302,211
Liability derivative fair value	[1]	11,941	2,936
Not Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Asset derivative notional amount		441,843	592,791
Asset derivative fair value	[1]	25,025	14,797
Liability derivative notional amount		4,909,732	5,804,625
Liability derivative fair value	[1]	33,554	28,248
Not Designated as Hedging Instrument | Investment Related Derivatives | Interest Rate Contract
Derivatives Fair Value [Line Items]
Asset derivative notional amount		0	394,597
Asset derivative fair value	[1]	0	206
Liability derivative notional amount		0	20,782
Liability derivative fair value	[1]	0	51
Not Designated as Hedging Instrument | Investment Related Derivatives | Foreign Exchange Contract
Derivatives Fair Value [Line Items]
Asset derivative notional amount		102,234	7,385
Asset derivative fair value	[1]	2,888	403
Liability derivative notional amount		144,707	207,182
Liability derivative fair value	[1]	1,702	4,442
Not Designated as Hedging Instrument | Investment Related Derivatives | Credit Exposure
Derivatives Fair Value [Line Items]
Asset derivative notional amount		8,433	2,408
Asset derivative fair value	[1]	652	165
Liability derivative notional amount		71,614	14,270
Liability derivative fair value	[1]	12,067	9,836
Not Designated as Hedging Instrument | Investment Related Derivatives | Financial Market Exposure
Derivatives Fair Value [Line Items]
Asset derivative notional amount		37	46,145
Asset derivative fair value	[1]	77	360
Liability derivative notional amount		26,500	33,670
Liability derivative fair value	[1]	417	34
Not Designated as Hedging Instrument | Financial Operations Derivatives | Credit Exposure
Derivatives Fair Value [Line Items]
Asset derivative notional amount		0	0
Asset derivative fair value	[1]	0	0
Liability derivative notional amount		0	0
Liability derivative fair value	[1]	0	0
Not Designated as Hedging Instrument | Other Non Investment Derivatives | Foreign Exchange Contract
Derivatives Fair Value [Line Items]
Asset derivative notional amount		194,566	0
Asset derivative fair value		2,009	0
Liability derivative notional amount		0	81,194
Liability derivative fair value		0	282
Not Designated as Hedging Instrument | Other Non Investment Derivatives | Other Credit Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount		29,874	31,060
Asset derivative fair value	[1]	31	60
Liability derivative notional amount		0	0
Liability derivative fair value	[1]	0	0
Not Designated as Hedging Instrument | Other Non Investment Derivatives | Guaranteed Minimum Income Benefit
Derivatives Fair Value [Line Items]
Asset derivative notional amount		46,032	46,249
Asset derivative fair value	[1]	19,368	13,603
Liability derivative notional amount		46,032	46,249
Liability derivative fair value	[1]	19,368	13,603
Not Designated as Hedging Instrument | Other Non Investment Derivatives | Modified Coinsurance Funds Withheld Contract
Derivatives Fair Value [Line Items]
Asset derivative notional amount	[2]	60,667	64,947
Asset derivative fair value	[1],[2]	0	0
Liability derivative notional amount		4,620,879	5,401,278	[2]
Liability derivative fair value	[1],[2]	$ 0	$ 0
[1]	Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, in the balance sheets on a net basis where the Company has both a legal right of offset and the intention to settle the contracts on a net basis.
[2]	The fair value movements in derivative assets and liabilities relating to modified coinsurance funds withheld contracts are included within the associated asset or liability at each period end on the face of the balance sheets. Notional amounts associated with reinsurance agreements under which the Company assumes reinsurance risk are recorded as asset derivative notional amounts. Notional amounts associated with the GreyCastle Life Retro Arrangements under which the Company cedes reinsurance risk are recorded as liability derivative notional amounts. Included in the liability derivative notional amount at December 31, 2015 is the cumulative net realized and unrealized loss on life retrocession embedded derivative of $463.9 million.

Derivative Instruments - Balanc

Derivative Instruments - Balance sheet offsetting (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative assets - gross amounts recognized in the balance sheet		$ 89,314	$ 136,659
Derivative assets - gross amounts offset in the balance sheet	[1]	3,087	696
Derivative assets - net amounts in the balance sheet		86,227	135,963
Derivative assets - financial instruments not offset in the balance sheet		0	0
Derivative assets - cash collateral not offset in the balance sheet		30,958	78,580
Derivative assets - net amount		55,269	57,383
Derivative liabilities - gross amounts recognized in the balance sheet		45,495	31,184
Derivative liabilities - gross amounts offset in the balance sheet	[1]	3,087	696
Derivative liabilities - net amounts in the balance sheet		42,408	30,488
Derivative liabilities - financial instruments not offset in the balance sheet		0	0
Derivative liabilities - cash collateral not offset in the balance sheet		0	0
Derivative liabilities - net amount		$ 42,408	$ 30,488
[1]	Other assets and other liabilities include derivative instruments. The derivative balances included in each category are reported on a gross basis by level with a netting adjustment presented separately in the Collateral and Counterparty Netting column. The fair values of the individual derivative contracts are reported gross in their respective levels based on the fair value hierarchy. For further details regarding derivative fair values and associated collateral received or paid see

Derivative Instruments - Hedged

Derivative Instruments - Hedged items - amount of gain/(loss) recognized in income attributable to risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments Gain Loss [Line Items]
Ineffective portion of hedging relationship - gain/(loss)	$ 0	$ (256)	$ 497
Designated as Hedging Instrument | Fair Value Hedging Member | Net realized and unrealized gains (losses) on derivative instruments [Member]
Derivative Instruments Gain Loss [Line Items]
Gain (loss) recognized in income on derivative	0	(15,663)	(22,568)
Ineffective portion of hedging relationship - gain/(loss)	0	(256)	497
Designated as Hedging Instrument | Fair Value Hedging Member | Net realized and unrealized gains (losses) on derivative instruments [Member] | Deposit Liabilities
Derivative Instruments Gain Loss [Line Items]
Gain (loss) recognized in income on derivative	0	0	0
Designated as Hedging Instrument | Fair Value Hedging Member | Net realized and unrealized gains (losses) on derivative instruments [Member] | Fixed Maturity Investments
Derivative Instruments Gain Loss [Line Items]
Gain (loss) recognized in income on derivative	0	15,407	23,065
Designated as Hedging Instrument | Fair Value Hedging Member | Net realized and unrealized gains (losses) on derivative instruments [Member] | Interest Rate Exposure
Derivative Instruments Gain Loss [Line Items]
Gain (loss) recognized in income on derivative	0	0	0
Designated as Hedging Instrument | Fair Value Hedging Member | Net realized and unrealized gains (losses) on derivative instruments [Member] | Foreign Exchange Exposure
Derivative Instruments Gain Loss [Line Items]
Gain (loss) recognized in income on derivative	$ 0	$ (15,663)	$ (22,568)

Derivative Instruments - Schedu

Derivative Instruments - Schedule of settlement of fair value hedges (Details) - Fair Value Hedging Member - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Notes Payable And Debt
Derivative [Line Items]
Cumulative reduction to interest expense	$ 0	$ 21,624
Fair Value Hedge Remaining Balance	$ 0	$ 0
Weighted average years to maturity	0 years	0 years
Deposit Liabilities
Derivative [Line Items]
Cumulative reduction to interest expense	$ 103,742	$ 95,333
Fair Value Hedge Remaining Balance	$ 129,454	$ 137,862
Weighted average years to maturity	21 years 7 months 6 days	23 years 2 months 12 days

Derivative Instruments - Sch123

Derivative Instruments - Schedule of derivative instruments designated as hedges of the net investment in a foreign operation (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Weighted average of U.S. dollar equivalent of foreign denominated net assets		$ 1,769,106	$ 2,384,508
Derivative gains (losses)	[1]	$ 106,876	$ 120,643
[1]	Derivative gains (losses) from derivative instruments designated as hedges of the net investment in a foreign operation are recorded in the cumulative translation adjustment account within AOCI for each period.

Derivative Instruments - Earnin

Derivative Instruments - Earnings relating to derivative instruments not formally designated as hedging instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments Gain Loss [Line Items]
Total derivatives not designated as hedging instruments	$ 53,123	$ 30,142	$ 7,301
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	0	(256)	497
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	53,123	29,886	7,798
Not Designated as Hedging Instrument | Investment Related Derivatives
Derivative Instruments Gain Loss [Line Items]
Interest rate exposure	(2,347)	15,959	5,065
Foreign exchange exposure	(1,542)	3,351	(948)
Credit exposure	(2,537)	400	(4,052)
Financial market exposure	(2,190)	411	6,302
Not Designated as Hedging Instrument | Financial Operations Derivatives
Derivative Instruments Gain Loss [Line Items]
Credit exposure	0	5,023	(2,437)
Not Designated as Hedging Instrument | Other Non Investment Derivatives
Derivative Instruments Gain Loss [Line Items]
Foreign exchange exposure	60,319	0	0
Credit exposure	1,375	0
Contingent capital facility			0
Guaranteed minimum income benefit contract	0	2,257	10,457
Modified coinsurance funds withheld contract	45	2,741	(7,086)
Life Funds Withheld Assets [Member]
Derivative Instruments Gain Loss [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	$ (151,691)	$ (488,222)	$ 0

Derivative Instruments - Compon

Derivative Instruments - Components of life retrocession embedded derivative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	$ 53,123	$ 29,886	$ 7,798
Life Funds Withheld Assets [Member]
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(13,083)	(450,831)
Net adjustments related to future policy benefit reserves, net of tax	(125,747)	(21,786)
Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets	(12,861)	(15,605)
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	(151,691)	(488,222)	$ 0
Life Funds Withheld Assets [Member] | Interest income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(193,568)	(134,634)
Life Funds Withheld Assets [Member] | Net realized and unrealized gains (losses
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	180,134	(318,065)
Life Funds Withheld Assets [Member] | Other
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	$ 351	$ 1,868

Derivative Instruments - Summar

Derivative Instruments - Summary of contingent credit features (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Collateral posted to counterparty	$ 0	$ 0
Contracts with downgrade provisions [Member]
Derivative [Line Items]
Aggregate fair value of derivative agreements with downgrade provisions in a net liability position	5,827	5,770
Collateral posted to counterparty	$ 0	$ 0

Derivative Instruments - Narrat

Derivative Instruments - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Derivative [Line Items]
Derivative assets - cash collateral not offset in the balance sheet		$ 30,958		$ 78,580
Collateral posted to counterparty		0		0
Net results from structured products		17,991	[1]	54,209	[2]	$ 23,791	[3]
Asset derivative fair value		89,314		136,659
Net realized and unrealized gains (losses) on derivative instruments		53,123		29,886		7,798
Fair Value Hedging Member | Deposit Liabilities
Derivative [Line Items]
Fair Value Hedge Remaining Balance		129,454		137,862
Fair Value Hedging Member | Structured Indemnity | Deposit Liabilities
Derivative [Line Items]
Fair Value Hedge Remaining Balance				47,000
Life Funds Withheld Assets [Member]
Derivative [Line Items]
Cumulative net realized and unrealized gains (losses) on life retrocession embedded derivative		(463,900)
Net realized and unrealized gains (losses) on derivative instruments		(151,691)		(488,222)		0
Not Designated as Hedging Instrument
Derivative [Line Items]
Asset derivative notional amount		441,843		592,791
Asset derivative fair value	[4]	25,025		14,797
Other Non Investment Derivatives | Not Designated as Hedging Instrument | Other Credit Derivatives [Member]
Derivative [Line Items]
Asset derivative notional amount		29,874		31,060
Asset derivative fair value	[4]	31		60
Net realized and unrealized gains (losses) on derivative instruments	[4]	100
Interest expense | Structured Indemnity
Derivative [Line Items]
Net results from structured products				28,700
Interest expense | Property and casualty operations
Derivative [Line Items]
Net results from structured products		$ (42,200)		$ (12,900)		$ (48,000)
[1]	The net results from P&C structured products include net investment income and interest expense of $60.4 million and $42.2 million, respectively.
[2]	The net results from P&C structured products include net investment income and interest expense of $68.0 million and $12.9 million, respectively.
[3]	The net results from P&C structured products include net investment income and interest expense of $71.9 million and $48.0 million, respectively.
[4]	Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, in the balance sheets on a net basis where the Company has both a legal right of offset and the intention to settle the contracts on a net basis.

Variable Interest Entities (Det

Variable Interest Entities (Details) - Equity interest attributable to third party investors in New Ocean - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Non-controlling interest in consolidated subsidiaries	$ 70.5	$ 58.4
Variable Interest Entity, Consolidated, Carrying Amount, Assets	175.8	139.9
New Ocean Capital Management Ltd
Variable Interest Entity [Line Items]
Non-controlling interest in consolidated subsidiaries	$ 0.4	$ 0.2

Commitments and Contingencies -

Commitments and Contingencies - Broker credit risk (Details) - Gross written premium - Property and casualty operations - Credit concentration risk	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Concentration Risk [Line Items]
Maximum percentage of ceded written premium	10.00%
AON Corporation and subsidiaries
Concentration Risk [Line Items]
Maximum percentage of ceded written premium	18.00%	18.00%	21.00%
Marsh & McLennan Companies
Concentration Risk [Line Items]
Maximum percentage of ceded written premium	19.00%	20.00%	23.00%
Willis Group and subsidiaries
Concentration Risk [Line Items]
Maximum percentage of ceded written premium	13.00%	11.00%	13.00%

Commitments and Contingencie130

Commitments and Contingencies - Future minimum operating lease payments (Details) $ in Thousands	Dec. 31, 2015USD ($)
Future minimum payments on operating leases:
2,016	$ 69,256
2,017	62,517
2,018	56,122
2,019	51,447
2,020	46,356
2021-2031	131,826
Total minimum future rentals	$ 417,524

Commitments and Contingencie131

Commitments and Contingencies - Future minimum capital lease payments (Details) $ in Thousands	Dec. 31, 2015USD ($)
Future minimum payments on capital leases:
2,016	$ 11,870
2,017	12,167
2,018	12,471
2,019	12,783
2,020	13,103
2021 - 2028	109,248
Total minimum future lease payments	$ 171,642

Commitments and Contingencie132

Commitments and Contingencies - Financial and other guarantee exposures(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Aggregate exposure outstanding	$ 80.8
Weighted average contractual term to maturity in years	24 years 2 months 12 days	25 years 2 months 12 days

Commitments and Contingencie133

Commitments and Contingencies - Narrative (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2015USD ($)Guarantee_contracts	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Commitments And Contingencies Disclosure [Line Items]
Additional investment commitment - other investments		$ 127,600
Time period over which commitment exists - limited partnerships		6 years
Additional investment commitment - investments in affiliates		$ 163,200
Time period over which commitment exists, investments in affiliates		4 years 10 months 24 days
Maximum percentage tax on branch profits, contingent		30.00%
Total rent expense under operating leases		$ 71,100	$ 36,600	$ 38,700
Capital lease asset recognized		73,400	82,800
Deferred gain on sale/leaseback transaction		22,300	$ 25,200
Future minimum lease payments		171,642
Total gross claim liability recorded		$ 0
Weighted average contractual term to maturity in years		24 years 2 months 12 days	25 years 2 months 12 days
Shareholders' equity | Credit concentration risk
Commitments And Contingencies Disclosure [Line Items]
Maximum percentage of aggregate direct investment in any single corporate issuer		5.00%
Letter of credit facility
Commitments And Contingencies Disclosure [Line Items]
Letters of credit, amount outstanding	[1]	$ 2,515,653	$ 1,790,561
Percentage of letters of credit collateralized by investment portfolios	[1]	50.90%	66.20%
Financial guarantee related to securities including some issued by European financials
Commitments And Contingencies Disclosure [Line Items]
Number of financial guarantee contracts | Guarantee_contracts		2
[1]	As of December 31, 2015 and December 31, 2014, there were fifteen and eight available credit facilities, respectively.

Share Capital - Authorized and

Share Capital - Authorized and issued (Details)		May. 01, 2015USD ($)$ / sharesshares	Oct. 15, 2011USD ($)	Mar. 15, 2007$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014$ / sharesshares	Dec. 31, 2015EUR (€)€ / sharesshares	Aug. 06, 2015USD ($)	Feb. 21, 2014USD ($)
Shareholders Equity Disclosure [Line Items]
Authorized share capital, value					$ 9,999,900		€ 40,000
Ordinary shares, shares authorized (in shares)					999,990,000	999,990,000	999,990,000
Ordinary shares, par value (in dollars per share) | $ / shares					$ 0.01	$ 0.01
Rollforward of ordinary shares issued and outstanding:
Balance at beginning of year, shares					255,182,955	278,253,000
Exercise of options, shares					480,000	424,000
Issue of shares					49,935,000	0
Net issuance of restricted shares, shares					1,581,000	1,246,000
Share buybacks, shares	[1]				(12,434,000)	(24,740,000)
Balance at end of year, shares					294,745,045	255,182,955
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Articles Of Association maximum voting power, percentage					10.00%
Ordinary shares
Shareholders Equity Disclosure [Line Items]
Ordinary shares, shares authorized (in shares)					500,000,000		500,000,000
Ordinary shares, par value (in dollars per share) | $ / shares					$ 0.01
Undesignated shares
Shareholders Equity Disclosure [Line Items]
Ordinary shares, shares authorized (in shares)					499,990,000		499,990,000
Ordinary shares, par value (in dollars per share) | $ / shares					$ 0.01
Subscriber shares
Shareholders Equity Disclosure [Line Items]
Ordinary shares, shares authorized (in shares)					40,000		40,000
Ordinary shares, par value (in dollars per share) | € / shares							€ 1
Series D preference ordinary shares
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Proceeds on issuance of preferred shares | $			$ 350,000,000
Series D preference ordinary shares | LIBOR
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Dividend rate, spread on LIBOR			3.12%
Series E preference ordinary shares
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Liquidation preference per share | $ / shares				$ 1,000
Preferred shares, shares issued				1,000,000
Preferred shares, stated dividend per share | $ / shares				$ 32.5
Preferred shares, par value | $ / shares				$ 0.01
Two Thousand Fourteen Share Repurchase Authorization [Member]
Ordinary share buybacks:
Share repurchase authorization | $									$ 1,000,000,000
Shares purchased and canceled during the period					4,500,000
Value of shares purchased and canceled during the period | $					$ 170,000,000
Amount remaining under share repurchase plan | $								$ 97,600,000
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Shares purchased and canceled during the period					4,500,000
Two Thousand Fifteen Share Repurchase Authorization [Member]
Ordinary share buybacks:
Share repurchase authorization | $								$ 1,000,000,000
Shares purchased and canceled during the period					7,900,000
Value of shares purchased and canceled during the period | $					$ 296,700,000
Amount remaining under share repurchase plan | $					$ 703,300,000
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Shares purchased and canceled during the period					7,900,000
Catlin Group Limited [Member]
Shareholders Equity Disclosure [Line Items]
Ordinary shares, par value (in dollars per share) | $ / shares		$ 0.01
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
XL Share issuance to Catlin shareholders		49,935,000
XL Share issuance consideration | $		$ 1,851,601,000
Catlin Group Limited [Member] | Noncumulative perpetual preferred shares
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Liquidation preference per share | $ / shares					$ 1,000
Preferred Stock, Shares Outstanding					600,000		600,000
Dividend rate, spread on LIBOR					7.249%
Preferred shares, par value | $ / shares					$ 0.01
Preferred Stock, Value, Outstanding | $					$ 562,300,000
Change In Dividend Rate If Shares Not Redeemed at Specified Date [Member] | Catlin Group Limited [Member] | Noncumulative perpetual preferred shares
Preferred shares and non-controlling interest in equity of consolidated subsidiaries:
Dividend rate, spread on LIBOR					2.975%
[1]	Includes share buybacks associated with authorized share buyback programs as well as purchases related to satisfying tax withholding obligations of employees in connection with the vesting of restricted shares granted under the Company’s equity compensation programs.

Share Capital - Options valuati

Share Capital - Options valuation assumptions (Details) - Stock options	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted average assumptions and option awards:
Dividend yield	2.00%	2.00%	2.00%
Risk free interest rate	1.70%	1.81%	1.14%
Volatility	21.60%	34.00%	37.00%
Expected lives	6 years	6 years	6 years

Share Capital - Options (Detail

Share Capital - Options (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2004
Summary of stock option plans:
Options exercised during the year		480,000	424,000
Summary of stock options and related activity:
Options exercised during the year		(480,000)	(424,000)
Stock options
Summary of stock option plans:
Options granted to purchase ordinary shares under directors and employees incentive compensation plans (shares)		1,974,000	1,025,000	1,047,000
Weighted average grant date fair value (per share)		$ 6.51	$ 8.60	$ 8.34
Total intrinsic value of stock options exercised		$ 8,546	$ 7,499	$ 16,076
Options exercised during the year		480,000	424,000	927,000
Compensation expense related to stock option plans		$ 8,961	$ 9,961	$ 8,294
Estimated tax benefit related to stock option plans		$ 0	$ (2)	$ 50
Summary of stock options and related activity:
Outstanding at beginning of year, shares		10,525,000
Granted, shares		1,974,000
Options exercised during the year		(480,000)	(424,000)	(927,000)
Canceled/expired, shares		(1,270,000)
Outstanding at end of year, shares		10,749,000	10,525,000
Options exercisable, shares		7,741,000
Options available for grant, shares	[1]	6,907,000
Outstanding at beginning of year, weighted average exercise price		$ 32.42
Granted, weighted average exercise price		36.43
Exercised, weighted average exercise price		20.79
Canceled/expired, weighted average exercise price		75.34
Outstanding at end of year, weighted average exercise price		28.59	$ 32.42
Options exercisable, weighted average exercise price		$ 26.43
Weighted average remaining contractual term		5 years 4 months 24 days	4 years 9 months 18 days
Weighted average remaining contractual term, options exercisable		4 years 1 month 6 days
Aggregate intrinsic value, beginning of year		$ 86,690
Aggregate intrinsic value, end of year		121,085	$ 86,690
Aggregate intrinsic value, options exercisable		105,990
Total unrecognized stock based compensation expense		$ 13,600
Number of non-vested options outstanding		3,000,000
Period for recognition of unrecognized expense		1 year 4 months 24 days
Number of stock options issued at an exercise price other than market price					295,000
Exercise price of options issued at above market price					$ 88
Market price at time of grant					$ 77.10
[1]	Available for grant includes shares that may be granted as either stock options, restricted stock, restricted stock units or performance units.

Share Capital - Restricted stoc

Share Capital - Restricted stock, restricted stock units and performance units (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Minimum
Summary of awards:
Vesting period required	3 years
Maximum
Summary of awards:
Vesting period required	4 years
Restricted stock awards
Summary of awards:
Granted, shares	44	46	181
Weighted average grant date fair value (per share)	$ 37.11	$ 31.86	$ 29.44
Aggregate grant date fair value	$ 1,613	$ 1,463	$ 5,325
Compensation expense	3,889	5,239	4,419
Estimated tax benefit (charge)	709	$ 1,233	$ 1,047
Total unrecognized stock based compensation expense	$ 300
Period for recognition of unrecognized expense	1 year
Award activity:
Unvested at beginning of period, shares	433
Granted, shares	44	46	181
Vested, shares	(202)
Unvested at end of period, shares	275	433
Unvested at beginning of period, weighted average grant date fair value	$ 36.41
Granted, weighted average grant date fair value	37.11
Vested, weighted average grant date fair value	29.08
Unvested at end of period, weighted average grant date fair value	$ 41.90	$ 36.41
Restricted stock units
Summary of awards:
Granted, shares	1,534	1,867	1,803
Aggregate grant date fair value	$ 55,540	$ 57,134	$ 51,829
Compensation expense	48,937	41,879	32,874
Estimated tax benefit (charge)	13,271	$ 11,607	$ 8,813
Total unrecognized stock based compensation expense	$ 61,000
Period for recognition of unrecognized expense	1 year 3 months 18 days
Vesting period required	3 years
Award activity:
Unvested at beginning of period, shares	3,248
Granted, shares	1,534	1,867	1,803
Vested, shares	(1,536)
Forfeited, shares	(176)
Unvested at end of period, shares	3,070	3,248
Unvested at beginning of period, weighted average grant date fair value	$ 28.93
Granted, weighted average grant date fair value	36.20
Vested, weighted average grant date fair value	27.67
Forfeited, weighted average grant date fair value	32.45
Unvested at end of period, weighted average grant date fair value	$ 32.99	$ 28.93
Performance units
Summary of awards:
Granted, shares	781	572	656
Potential maximum share payout	1,563	1,144	1,312
Aggregate grant date fair value	$ 28,082	$ 16,345	$ 17,753
Compensation expense	12,942	24,089	1,041
Estimated tax benefit (charge)	1,459	$ 4,250	$ (176)
Total unrecognized stock based compensation expense	$ 27,900
Period for recognition of unrecognized expense	1 year 10 months 24 days
Vesting period required	3 years
Award activity:
Unvested at beginning of period, shares	2,540
Granted, shares	781	572	656
Vested, shares	(750)
Forfeited, shares	(63)
Performance driven reduction, shares	(627)
Unvested at end of period, shares	1,881	2,540
Unvested at beginning of period, weighted average grant date fair value	$ 25.24
Granted, weighted average grant date fair value	35.94
Vested, weighted average grant date fair value	19.35
Forfeited, weighted average grant date fair value	30.03
Performance driven reduction, weighted average grant date fair value	27.74
Unvested at end of period, weighted average grant date fair value	$ 31.02	$ 25.24
Performance units | Minimum
Summary of awards:
Final payout percentage	0.00%
Performance units | Maximum
Summary of awards:
Final payout percentage	200.00%

Share Capital - Restricted cash

Share Capital - Restricted cash units (Details) - Deferred compensation, share-based payments shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares | shares	2.6
Aggregate grant date fair value | $	$ 94.5
Three Year Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period required	3 years
Two Year Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period required	2 years

Retirement Plans - Funded statu

Retirement Plans - Funded status of plan by geographic location (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	$ (42,763)	$ (43,843)
US Plan
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	(16,306)	(13,124)
UK Plans
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	(4,650)	(7,742)
Europe plans
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	$ (21,807)	$ (22,977)

Retirement Plans - Projected be

Retirement Plans - Projected benefit obligation and plan assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets acquired due to Catlin Acquisition			$ 0
Projected benefit obligation assumed due to Catlin Acquisition			0
Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets acquired due to Catlin Acquisition	$ 33,131
Projected benefit obligation assumed due to Catlin Acquisition	28,414
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	93,124		81,976
Service cost	1,494	[1]	1,279	[1]	$ 1,491
Interest cost	4,382		3,747
Actuarial (gain) loss	2,821		13,402
Benefits and expenses paid	(3,747)		(2,761)
Foreign currency (gains) losses	(4,047)		(3,817)
Settlements	(276)		(702)
Projected benefit obligation, end of year	122,165		93,124		81,976
Change in plan assets:
Fair value of plan assets - beginning of year	49,281		47,158
Actual return on plan assets	(119)		3,543
Employer contributions	1,775		1,187
Benefits and expenses paid	(3,305)		(1,932)
Foreign currency (gains) losses	(1,361)		(675)
Fair value of plan assets - end of year	79,402		49,281		$ 47,158
Funded status - end of year	(42,763)		(43,843)
Accrued pension liability	$ 42,763		$ 43,843
[1]	Service costs include cost of living adjustments on curtailed plans.

Retirement Plans - Net benefit

Retirement Plans - Net benefit cost (Details) - Defined benefit plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,494	[1]	$ 1,279	[1]	$ 1,491
Interest cost	4,381		3,747		3,589
Expected return on plan assets	(3,903)		(2,859)		(3,096)
Amortization of net actuarial loss	1,617		812		1,440
Net benefit cost	$ 3,589		$ 2,979		$ 3,424
[1]	Service costs include cost of living adjustments on curtailed plans.

Retirement Plans - Assumptions

Retirement Plans - Assumptions used (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
US Plan
Net benefit cost - weighted average assumptions
Discount rate	3.91%	4.95%
Expected long-term rate of return on plan assets	6.00%	6.50%
Benefit obligation - weighted-average assumptions
Discount rate	4.25%	3.91%
UK Plans
Net benefit cost - weighted average assumptions
Discount rate	3.70%	4.60%
Expected long-term rate of return on plan assets	3.48%	4.60%
Rate of compensation increase	3.96%	5.50%
Benefit obligation - weighted-average assumptions
Discount rate	3.70%	4.60%
Rate of compensation increase	3.96%	5.50%
Europe plans
Net benefit cost - weighted average assumptions
Discount rate	2.42%	3.50%
Rate of compensation increase	2.50%	2.50%
Benefit obligation - weighted-average assumptions
Discount rate	2.42%	2.40%
Rate of compensation increase	2.50%	2.50%

Retirement Plans - UK plans (De

Retirement Plans - UK plans (Details) - UK Plans $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)employee	Dec. 31, 2014USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	3.48%	4.60%
Fair value of plan assets	$ 42,716	$ 11,184
Funding deficit based on most recent valuation	$ 2,400
Period over which the deficit is being funded	10 years
Transferred to defined contribution plan
Defined Benefit Plan Disclosure [Line Items]
Number of members in the plan | employee	6
Accrued pension liability	$ 4,800	$ 3,800
Still employed by company
Defined Benefit Plan Disclosure [Line Items]
Number of members in the plan | employee	4
Equities
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	6.20%	7.40%
Fair value of plan assets	$ 7,893	$ 7,787
Gilts
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	2.40%	3.60%
Fair value of plan assets	$ 17,856	$ 1,579
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	3.40%	4.60%
Fair value of plan assets	$ 16,915	$ 1,594
Other (cash)
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	1.80%	4.00%
Fair value of plan assets	$ 52	$ 224

Retirement Plans - Expected fut

Retirement Plans - Expected future benefit payments of US plan (Details) $ in Thousands	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,016	$ 1,422
2,017	1,453
2,018	1,481
2,019	1,764
2,020	1,934
2021 - 2025	12,936
US Plan
Defined Benefit Plan Disclosure [Line Items]
2,016	988
2,017	1,023
2,018	1,054
2,019	1,240
2,020	1,396
2021 - 2025	9,904
Benefits equalization plan
Defined Benefit Plan Disclosure [Line Items]
2,016	434
2,017	430
2,018	427
2,019	524
2,020	538
2021 - 2025	$ 3,032

Retirement Plans - Narrative (D

Retirement Plans - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)funds	Dec. 31, 2014USD ($)funds	Dec. 31, 2013USD ($)
Defined Benefit Plan Disclosure [Line Items]
Vesting period for defined contribution plan	5 years
Expense recognized on defined contribution plans	$ 87.5	$ 56.6	$ 49.4
Number of years of compensation for calculating benefit	3 years
Number of years of employment considered at retirement	10 years
Estimated employer contributions in next fiscal year	$ 0.4
US Plan
Defined Benefit Plan Disclosure [Line Items]
Number of mutual funds held by plan | funds	3	2
Fair value of plan assets	$ 36.7	$ 38.1
Benefits equalization plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 3.2

Accumulated Other Comprehens146

Accumulated Other Comprehensive Income - Changes in AOCI, net of tax (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period		$ 1,484,458	$ 736,657	$ 1,520,020
OCI before reclassifications		(514,094)	916,952	(795,980)
Amounts reclassified from AOCI		(326,979)	(128,094)	(85,692)
Tax benefit (expense)		43,231	(41,057)	98,309
Net current period OCI - net of tax		(797,842)	747,801	(783,363)
Balance, net of tax, end of period		686,616	1,484,458	736,657
Cumulative adjustments recorded to value of future policy benefit reserves, amount		(170,688)	400,456	44,660
Unrealized Gains (Losses) on Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period	[1]	1,590,114	822,432	1,591,210
OCI before reclassifications	[1]	(474,304)	954,326	(742,768)
Amounts reclassified from AOCI	[1]	(346,911)	(143,330)	(119,970)
Tax benefit (expense)	[1]	34,195	(43,314)	93,960
Net current period OCI - net of tax	[1]	(787,020)	767,682	(768,778)
Balance, net of tax, end of period	[1]	803,094	1,590,114	822,432
Cumulative adjustments recorded to value of future policy benefit reserves, amount		(170,700)
Cumulative impact of net unrealized gains (losses) on future policy benefit reserve		274,400	445,100
OTTI Losses Recognized in AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period		(76,047)	(89,190)	(121,371)
OCI before reclassifications		0	0	0
Amounts reclassified from AOCI		18,987	14,082	32,193
Tax benefit (expense)		(442)	(939)	(12)
Net current period OCI - net of tax		18,545	13,143	32,181
Balance, net of tax, end of period		(57,502)	(76,047)	(89,190)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period		(11,188)	14,541	69,399
OCI before reclassifications		(33,690)	(26,497)	(62,934)
Amounts reclassified from AOCI		0	87	206
Tax benefit (expense)		8,375	681	7,870
Net current period OCI - net of tax		(25,315)	(25,729)	(54,858)
Balance, net of tax, end of period		(36,503)	(11,188)	14,541
Underfunded Pension Liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period		(20,789)	(13,239)	(20,892)
OCI before reclassifications		(6,100)	(10,877)	9,722
Amounts reclassified from AOCI		1,145	812	1,440
Tax benefit (expense)		1,103	2,515	(3,509)
Net current period OCI - net of tax		(3,852)	(7,550)	7,653
Balance, net of tax, end of period		(24,641)	(20,789)	(13,239)
Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, net of tax, beginning of period		2,368	2,113	1,674
OCI before reclassifications		0	0	0
Amounts reclassified from AOCI		(200)	255	439
Tax benefit (expense)		0	0	0
Net current period OCI - net of tax		(200)	255	439
Balance, net of tax, end of period		$ 2,168	$ 2,368	$ 2,113
[1]	Included in these amounts is the impact of Shadow Adjustments. As of December 31, 2014, $445.1 million was recorded. During the year ended December 31, 2015, additional net impacts of $(170.7) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $274.4 million at December 31, 2015.

Accumulated Other Comprehens147

Accumulated Other Comprehensive Income - Details about AOCI components (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized and unrealized gains (losses) on derivative instruments		$ 53,123	$ 29,886	$ 7,798
Operating Expenses		(1,966,939)	(1,341,315)	(1,213,178)
Exchange gains (losses) before tax		(22,504)	37,568	28,243
Amounts reclassified from AOCI		(326,979)	(128,094)	(85,692)
Provision for income tax		19,161	(96,897)	(77,505)
Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	[1]	(346,911)	(143,330)	(119,970)
OTTI Losses Recognized in AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		18,987	14,082	32,193
Foreign Currency Translation Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		0	87	206
Underfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		1,145	812	1,440
Cash Flow Hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(200)	255	439
Life Funds Withheld Assets [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		223,272	5,067	0
OTTI on investments		(13,357)	(20,587)	0
Net adjustments related to future policy benefit reserves, net of tax		(125,747)	(21,786)
Net realized and unrealized gains (losses) on derivative instruments		(151,691)	(488,222)	$ 0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(326,979)	(128,094)
Provision for income tax		7,164	(1,974)
Total amount reclassified from AOCI, net of tax		(319,815)	(130,068)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		(316,508)	(175,639)
OTTI on investments		95,344	54,095
Amounts reclassified from AOCI		(346,911)	(143,330)
Provision for income tax		7,597	(1,593)
Total amount reclassified from AOCI, net of tax		(339,314)	(144,923)
Reclassification out of Accumulated Other Comprehensive Income [Member] | OTTI Losses Recognized in AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		18,014	11,848
OTTI on investments		973	2,234
Amounts reclassified from AOCI		18,987	14,082
Provision for income tax		(32)	(175)
Total amount reclassified from AOCI, net of tax		18,955	13,907
Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Currency Translation Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		0	87
Provision for income tax		0	0
Total amount reclassified from AOCI, net of tax		0	87
Reclassification out of Accumulated Other Comprehensive Income [Member] | Underfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating Expenses		1,145	812
Provision for income tax		(401)	(206)
Total amount reclassified from AOCI, net of tax		744	606
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(200)	255
Provision for income tax		0	0
Total amount reclassified from AOCI, net of tax		(200)	255
Reclassification out of Accumulated Other Comprehensive Income [Member] | Life Funds Withheld Assets [Member] | Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net adjustments related to future policy benefit reserves, net of tax		$ (125,747)	$ (21,786)
[1]	Included in these amounts is the impact of Shadow Adjustments. As of December 31, 2014, $445.1 million was recorded. During the year ended December 31, 2015, additional net impacts of $(170.7) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $274.4 million at December 31, 2015.

Dividends (Details)

Dividends (Details) - USD ($) $ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

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, 2015

Dec. 31, 2014

Dec. 31, 2013

Feb. 18, 2016

Jan. 12, 2016

Oct. 30, 2015

Dividends Paid [Line Items]

Dividends per share paid on ordinary shares

$ 0.72

$ 0.64

$ 0.56

Ordinary shares

Dividends Paid [Line Items]

Dividends per share paid on ordinary shares

$ 0.20

$ 0.2

$ 0.16

$ 0.16

$ 0.16

$ 0.16

$ 0.16

$ 0.16

$ 0.14

$ 0.14

$ 0.14

$ 0.14

Series D preference ordinary shares

Dividends Paid [Line Items]

Dividends on preference ordinary shares

[1],[2]

$ 11.8

$ 11.7

$ 12.3

Dividends declared and payable per share

$ 8.7787

Series E preference ordinary shares

Dividends Paid [Line Items]

Dividends on preference ordinary shares

[3]

65.1

65.1

65.1

Subsequent Event [Member] | Series D preference ordinary shares

Dividends Paid [Line Items]

Dividends declared and payable per share

$ 9.3490

Subsequent Event [Member] | Series E preference ordinary shares

Dividends Paid [Line Items]

Dividends declared and payable per share

$ 32.50

Catlin Group Limited [Member] | Noncumulative perpetual preferred shares

Dividends Paid [Line Items]

Dividends on preference ordinary shares

[4]

$ 21.8

$ 0

$ 0

Catlin Group Limited [Member] | Subsequent Event [Member] | Noncumulative perpetual preferred shares

Dividends Paid [Line Items]

Dividends declared and payable per share

$ 21,750,000

[1]

On February 19, 2016, the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $9.349 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016.

[2]

On October 30, 2015, the Company announced that the Board of Directors of XL-Cayman resolved to pay a dividend of $8.7787 per share on XL-Cayman’s Series D Preference Ordinary Shares. The dividend was paid on January 15, 2016 to all shareholders of record at January 1, 2016.

[3]

On February 19, 2016, the Company announced that the Board of Directors of XL-Cayman, resolved on February 18, 2016 to pay a dividend of $32.50 per share on XL-Cayman’s Series E Preference Ordinary Shares. The dividend will be paid on April 15, 2016 to all shareholders of record at April 1, 2016.

[4]

On January 12, 2016, the Board of Directors of Catlin-Bermuda resolved to pay a dividend in the aggregate amount of $21.8 million on CICL Prefs. The dividend was paid on January 19, 2016 to all shareholders of record at December 31, 2015.

Taxation - Summary of tax years

Taxation - Summary of tax years open to examination by jurisdiction (Details)	12 Months Ended
	Dec. 31, 2015
United States
Income Tax Examination [Line Items]
Year under Examination	2,013
United States | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2,012
United States | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2,015
Ireland | Minimum
Income Tax Examination [Line Items]
Year under Examination	2,006
Open Tax Year	2,006
Ireland | Maximum
Income Tax Examination [Line Items]
Year under Examination	2,009
Open Tax Year	2,015
United Kingdom | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2,013
United Kingdom | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2,015
Germany | Minimum
Income Tax Examination [Line Items]
Year under Examination	2,010
Open Tax Year	2,010
Germany | Maximum
Income Tax Examination [Line Items]
Year under Examination	2,013
Open Tax Year	2,015
Switzerland | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2,011
Switzerland | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2,015
France | Minimum
Income Tax Examination [Line Items]
Year under Examination	2,013
Open Tax Year	2,013
France | Maximum
Income Tax Examination [Line Items]
Year under Examination	2,014
Open Tax Year	2,015

Taxation - Distribution of pre-

Taxation - Distribution of pre-tax income by jurisdiction and components of income tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Distribution of pre-tax income by jurisdiction:
U.S.	$ (5,931)	$ 228,708	$ 188,503
Non U.S.	1,300,109	137,027	1,025,649
Income (loss) before income taxes	1,294,178	365,735	1,214,152
Current expense:
U.S.	(22,698)	45,598	49,566
Non U.S.	67,784	81,371	41,921
Total current expense	45,086	126,969	91,487
Deferred expense (benefit):
U.S.	(63,491)	8,572	700
Non U.S.	(756)	(38,644)	(14,682)
Total deferred expense (benefit)	(64,247)	(30,072)	(13,982)
Total tax expense	$ (19,161)	$ 96,897	$ 77,505

Taxation - Tax rates by jurisdi

Taxation - Tax rates by jurisdiction (Details)	12 Months Ended
	Dec. 31, 2015
Ireland | Active income
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	12.50%	[1]
Ireland | Passive income
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	25.00%	[1]
Bermuda
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	0.00%
United States
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	35.00%
United Kingdom
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	20.25%
Switzerland | Active income
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	7.83%	[2]
Switzerland | Passive income
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	21.20%	[2]
Germany
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	15.00%
France
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	38.00%
[1]	The different applicable statutory taxation rates in Ireland relate to entities classified as trading or non-trading companies.
[2]	The different applicable statutory taxation rates in Switzerland relate to entities classified as trading or holding companies.

Taxation - Reconciliation of ef

Taxation - Reconciliation of effective tax rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected tax provision at weighted average rate	$ (50,797)	$ 132,775	$ 43,092
Permanent differences:
Non taxable (income) loss	(23,036)	(19,870)	(50,745)
Revision to prior year estimates	7,402	2,016	8,551
State, local and foreign taxes	27,499	47,078	12,225
Valuation allowance	9,517	(181)	5,754
Net allocated investment income	(405)	3,399	5,949
Stock options	(433)	411	1,501
Non-deductible expenses	42,839	22,556	23,662
Realized capital loss carry-forward valuation allowance reduction	2,075	(2,916)	0
Adjustments related to Life Retro Arrangements	(35,045)	(99,535)	0
Non-taxable reserve release	(11,877)	3,974	(2,484)
Uncertain tax positions	13,100	7,190	30,000
Total tax expense	$ (19,161)	$ 96,897	$ 77,505

Taxation - Components of deferr

Taxation - Components of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net unpaid loss reserve discount	$ 111,584	$ 90,262
Net unearned premiums	80,434	72,752
Compensation liabilities	94,013	77,578
Net operating loss	181,295	49,834
Investment adjustments	14,399	13,022
Pension	10,370	8,114
Bad debt reserve	7,425	6,626
Amortizable goodwill	5,396	6,694
Net unrealized depreciation on investments	5,051	1,484
Stock options	16,192	11,985
Depreciation	13,299	7,599
Net realized capital losses	98,756	97,189
Deferred intercompany capital losses	26,164	57,427
Untaxed Lloyd's result	3,769	7,254
Deferred acquisition costs	31,133	11,386
Currency translation adjustments	6,280	0
Other	24,977	2,282
Deferred tax asset, gross of valuation allowance	730,537	521,488
Valuation allowance	276,301	207,062
Deferred Tax Assets, net of valuation allowance	454,236	314,426
Deferred tax liabilities:
Net unrealized appreciation on investments	51,010	63,642
Unremitted earnings	3,739	5,125
Deferred acquisition costs	8,308	2,737
Currency translation adjustments	1,210	3,969
Regulatory reserves	64,352	65,965
Investment adjustment	6,373	12,061
Untaxed Lloyd's result	0	11,422
Depreciation expense	11,500	0
Syndicate capacity	92,756	0
Intangible assets	40,126	0
Other	13,202	11,260
Deferred tax liability	292,576	176,181
Net deferred tax assets	$ 161,660	$ 138,245

Taxation - Summary of valuation

Taxation - Summary of valuation allowance (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Valuation Allowance [Line Items]
Valuation allowance	$ 276,301	$ 207,062
Switzerland
Valuation Allowance [Line Items]
Valuation allowance	7,818	1,459
Ireland
Valuation Allowance [Line Items]
Valuation allowance	93,396	72,363
United States
Valuation Allowance [Line Items]
Valuation allowance	106,624	123,695
United Kingdom
Valuation Allowance [Line Items]
Valuation allowance	46,732	1,632
Other
Valuation Allowance [Line Items]
Valuation allowance	$ 21,731	$ 7,913

Taxation - Reconciliation of un

Taxation - Reconciliation of unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of the year	$ 37,190	$ 30,000	$ 0
Increases for tax positions taken during the year	20,370	12,182	9,591
Increases for tax positions taken in prior years (1)	38,650	15,304	20,409
Decreases for tax positions taken in prior years	(4,850)	(20,296)	0
Decreases for lapse of the applicable statute of limitations	(10,770)	0	0
Unrecognized tax benefits, end of the year	$ 80,590	$ 37,190	$ 30,000

Taxation - Narrative (Details)

Taxation - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	May. 01, 2015	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Line Items]
Deferred tax asset, per balance sheet	$ 282,311	$ 204,491
Deferred tax liability, per balance sheet	120,651	66,246
Valuation allowance	276,301	207,062
Increase (decrease) in valuation allowance, amount	69,200
Net realized capital losses	98,756	97,189
Excess tax benefits on share-based compensation	9,200	4,000
Accrued interest and penalties	400
Unrecognized tax benefits	80,590	37,190		$ 30,000	$ 0
United States
Income Tax Disclosure [Line Items]
Valuation allowance	106,624	123,695
Capital loss valuation allowance, amount	66,800
Capital loss carryforwards, tax effected	66,800
Capital loss carryforwards available	190,800
Net operating loss carryforwards, amount	108,000
Net operating loss carryforwards, tax effected	37,800
United States | Deferred tax asset restricted under Internal Revenue Code Section 382
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, amount	48,300
United States | Deferred intercompany capital losses
Income Tax Disclosure [Line Items]
Capital loss valuation allowance, amount	26,200
Capital loss carryforwards, tax effected	26,200
Capital loss carryforwards available	74,800
United States | Expiring in 2016
Income Tax Disclosure [Line Items]
Capital loss carryforwards available	33,800
United States | Expiring in future years
Income Tax Disclosure [Line Items]
Capital loss carryforwards available	157,000
Ireland
Income Tax Disclosure [Line Items]
Valuation allowance	93,396	72,363
Capital loss carryforwards, tax effected	30,500
Capital loss carryforwards available	122,100
Net operating loss carryforwards, amount	460,000
Net operating loss carryforwards valuation allowance, amount	88,000
Net operating loss carryforwards, tax effected	57,500
United Kingdom
Income Tax Disclosure [Line Items]
Valuation allowance	46,732	1,632
Capital loss valuation allowance, amount	46,000
Capital loss carryforwards, tax effected	1,400
Net operating loss carryforwards, amount	290,000
Net operating loss carryforwards, tax effected	58,000
Net realized capital losses	7,200
Switzerland
Income Tax Disclosure [Line Items]
Valuation allowance	7,818	$ 1,459
Net operating loss carryforwards, amount	118,900
Net operating loss carryforwards valuation allowance, amount	7,700
Net operating loss carryforwards, tax effected	9,200
Switzerland | Carryforwards expiring In 2018
Income Tax Disclosure [Line Items]
Capital loss carryforwards available	1,800
Switzerland | Carryforwards expiring In 2019
Income Tax Disclosure [Line Items]
Capital loss carryforwards available	47,000
Switzerland | Expiring in future years
Income Tax Disclosure [Line Items]
Capital loss carryforwards available	$ 70,100
Catlin Group Limited [Member]
Income Tax Disclosure [Line Items]
Unrecognized tax benefits			$ 30,300
Other liabilities | Catlin Group Limited [Member]
Income Tax Disclosure [Line Items]
Unrecognized tax benefits			4,800
Deferred tax liabilities | Catlin Group Limited [Member]
Income Tax Disclosure [Line Items]
Unrecognized tax benefits			$ 25,500

Statutory Financial Data (Detai

Statutory Financial Data (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2015USD ($)subsidiary	Dec. 31, 2014USD ($)subsidiary	Dec. 31, 2013USD ($)
XL Ireland [Member]
Statutory Accounting Practices [Line Items]
Cash and investments, net of liabilities associated with cash sweeping arrangements		$ 11,600	$ 22,400
XL Cayman [Member]
Statutory Accounting Practices [Line Items]
Cash and investments, net of liabilities associated with cash sweeping arrangements		900,000	900,000
Bermuda
Statutory Accounting Practices [Line Items]
Required statutory capital and surplus	[1]	7,722,123	6,194,832
Actual statutory capital and surplus	[1],[2]	11,112,176	10,309,895
Statutory net income (loss)		$ 1,513,924	361,022	$ 1,241,878
BSCR level for principal operating subsidiaries		100.00%
Maximum permitted dividends as a percentage of prior year statutory capital and surplus		25.00%
Maximum permitted dividends as a percentage of statutory capital		15.00%
Maximum dividend permitted without affidavit		$ 2,800,000	1,400,000
United States
Statutory Accounting Practices [Line Items]
Required statutory capital and surplus	[3]	747,313	668,794
Actual statutory capital and surplus	[2],[3]	2,234,767	2,233,596
Statutory net income (loss)		$ 17,574	155,751	124,310
RBC level for certain operating subsidiaries		100.00%
Maximum permitted dividends as a percentage of statutory policyholder surplus		10.00%
Maximum permitted dividends as a percentage of "Adjusted net investment income"		100.00%
United States | XL Reinsurance America, Inc. [Member]
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[2],[3]	$ 2,000,000
Maximum dividend permitted without affidavit		31,700
Statutory earned surplus, amount		$ 31,700	205,500
Number of property and casualty subsidiaries | subsidiary		7
United States | Catlin Specialty Insurance Company [Member]
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[2],[3]	$ 213,100
Maximum dividend permitted without affidavit		$ 0
Number of property and casualty subsidiaries | subsidiary		3
Europe, UK, and other
Statutory Accounting Practices [Line Items]
Required statutory capital and surplus		$ 4,445,247	1,604,721
Actual statutory capital and surplus	[2]	6,054,122	2,712,552
Statutory net income (loss)		(125,758)	$ 215,787	$ 1,465
Ireland
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus		1,100,000
Distributable reserves, amount		2,900,000
Funds at Lloyds [Member]
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus		1,600,000
United Kingdom
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus		3,000,000
Switzerland
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus		$ 1,800,000
Statutory earned surplus deficit | United States | XL Reinsurance America, Inc. [Member]
Statutory Accounting Practices [Line Items]
Number of property and casualty subsidiaries | subsidiary		2	0
Statutory earned surplus deficit | United States | Catlin Specialty Insurance Company [Member]
Statutory Accounting Practices [Line Items]
Number of property and casualty subsidiaries | subsidiary		3
[1]	Required statutory capital and surplus at December 31, 2015 represents 100% Bermuda Solvency Capital Requirement ("BSCR") level for the top Bermuda operating subsidiary, XL Insurance (Bermuda) Ltd, calculated on a consolidated basis (and therefore includes a BSCR requirement for all regions).
[2]	Statutory assets in Bermuda include investments in other U.S. and international subsidiaries reported separately herein.
[3]	Required statutory capital and surplus represents 100% Risk-Based Capital level for principal U.S. operating subsidiaries.

Computation of Earnings Per 158

Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent - Computation of basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basic earnings per ordinary share and ordinary share equivalents:
Net income (loss) attributable to ordinary shareholders									$ 1,207,152	$ 188,340	$ 1,059,916
Weighted average ordinary shares outstanding									286,194	267,103	287,801
Basic earnings per ordinary share & ordinary share equivalents outstanding (in Dollars per share)	$ 0.77	$ 0.09	$ 3.16	$ 0.14	$ 0.54	$ 0.27	$ (1.03)	$ 0.93	$ 4.22	$ 0.71	$ 3.68
Diluted earnings per ordinary share and ordinary share equivalents:
Weighted average ordinary shares outstanding									286,194	267,103	287,801
Impact of share based compensation and certain conversion features									4,805	4,424	4,268
Weighted average ordinary shares outstanding - diluted									290,999	271,527	292,069
Diluted earnings per ordinary share & ordinary share equivalents outstanding (in Dollars per share)	$ 0.76	$ 0.09	$ 3.11	$ 0.14	$ 0.53	$ 0.27	$ (1.03)	$ 0.91	$ 4.15	$ 0.69	$ 3.63
Dividends per share paid on ordinary shares									$ 0.72	$ 0.64	$ 0.56

Computation of Earnings Per 159

Computation of Earnings Per Ordinary Share and Ordinary Share Equivalent - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock compensation plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2.5	5.5	6

Related Party Transactions - Sc

Related Party Transactions - Schedule of related party transactions activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)management_company		Dec. 31, 2014USD ($)management_company	Dec. 31, 2013USD ($)
Related Party Transaction [Line Items]
Reported net premiums written	$ 7,951,063		$ 5,944,841	$ 6,199,404
Net losses and loss expenses incurred	4,766,200		3,258,393	3,731,464
Reported acquisition costs	$ 1,317,448	[1]	$ 738,118	909,323
Number of investment management companies | management_company	6		6
Other strategic affiliates or subsidiaries
Related Party Transaction [Line Items]
Reported net premiums written	$ 42,042		$ 91,261	73,085
Net losses and loss expenses incurred	13,246		38,927	29,042
Reported acquisition costs	$ 14,682		$ 35,711	$ 25,275
[1]	The Company has reflected the amortization of certain fair value adjustments recorded in conjunction with the Catlin Acquisition within the respective segments.

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) $ in Millions	Jul. 24, 2015USD ($)	Dec. 31, 2015management_company	Dec. 31, 2014management_company
Related Party Transaction [Line Items]
Number of investment management companies		6	6
Percentage ownership of subsidiaries		100.00%	100.00%
Related Party Transactions Number of Investment Technology Service Firms		2	1
New Energy Risk Inc. [Member]
Related Party Transaction [Line Items]
Business acquisition, percentage of voting interests acquired	63.63%
Cash consideration | $	$ 8.8
Business combination, step acquisition, equity interest in acquiree, including subsequent acquisition, percentage	94.79%
Noncontrolling interest, ownership percentage by noncontrolling owners	5.21%
New Energy Risk Inc. [Member]
Related Party Transaction [Line Items]
Percentage ownership of subsidiaries		100.00%

Unaudited Quarterly Financia162

Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interim Reporting [Line Items]
Net premiums earned									$ 8,226,425	$ 5,895,070	$ 6,309,521
Underwriting profit (loss)									$ 587,409	$ 585,907	$ 245,191
Net income (loss) attributable to ordinary shareholders	$ 228,550	$ 27,282	$ 915,039	$ 36,281	$ 139,499	$ 72,384	$ (279,260)	$ 255,717
Earnings (loss) per ordinary share and ordinary share equivalent - basic (in dollars per share)	$ 0.77	$ 0.09	$ 3.16	$ 0.14	$ 0.54	$ 0.27	$ (1.03)	$ 0.93	$ 4.22	$ 0.71	$ 3.68
Earnings (loss) per ordinary share and ordinary share equivalent - diluted (in dollars per share)	$ 0.76	$ 0.09	$ 3.11	$ 0.14	$ 0.53	$ 0.27	$ (1.03)	$ 0.91	$ 4.15	$ 0.69	$ 3.63
Operating Segments [Member] | Property and casualty operations
Interim Reporting [Line Items]
Net premiums earned	$ 2,375,155	$ 2,405,740	$ 2,063,795	$ 1,319,494	$ 1,413,161	$ 1,453,673	$ 1,438,076	$ 1,412,528	$ 8,164,184	$ 5,717,438	$ 6,014,099
Underwriting profit (loss)	183,458	114,118	208,779	146,836	218,850	144,375	167,947	144,874	$ 653,191	$ 676,046	$ 451,062
Corporate and other
Interim Reporting [Line Items]
Net premiums earned	$ 11,665	$ 17,812	$ 18,258	$ 14,506	$ 23,064	$ 19,739	$ 58,518	$ 76,311

Schedule I - Consolidated Su163

Schedule I - Consolidated Summary of Investments - other than Investments in Related Parties (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	$ 35,492,043	$ 29,753,876
Fair Value		36,495,720	31,750,906
Amount Presented in the Balance Sheet		36,482,984	31,733,663
Other investments
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	1,197,674	1,002,871
Fair Value		1,445,793	1,265,682
Amount Presented in the Balance Sheet		1,433,057	1,248,439
Trading | Life Funds Withheld Assets [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	1,323,785	1,180
Fair Value		1,296,029	1,171
Amount Presented in the Balance Sheet		1,296,029	1,171
Trading | Life Funds Withheld Assets [Member] | Fixed maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	1,263,609	1,180
Fair Value		1,235,699	1,171
Amount Presented in the Balance Sheet		1,235,699	1,171
Trading | Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	4,957	0
Fair Value		4,990	0
Amount Presented in the Balance Sheet		4,990	0
Trading | Life Funds Withheld Assets [Member] | RMBS - Agency
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	370	0
Fair Value		368	0
Amount Presented in the Balance Sheet		368	0
Trading | Life Funds Withheld Assets [Member] | CMBS
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	4,874	0
Fair Value		4,803	0
Amount Presented in the Balance Sheet		4,803	0
Trading | Life Funds Withheld Assets [Member] | Other asset-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	26,405	0
Fair Value		25,700	0
Amount Presented in the Balance Sheet		25,700	0
Trading | Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	373,492	0
Fair Value		370,261	0
Amount Presented in the Balance Sheet		370,261	0
Trading | Life Funds Withheld Assets [Member] | Short-term investments
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	60,176	0
Fair Value		60,330	0
Amount Presented in the Balance Sheet		60,330	0
AFS
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	32,970,584	28,749,825
Fair Value		33,753,898	30,484,053
Amount Presented in the Balance Sheet		33,753,898	30,484,053
AFS | Exclude Life Funds Withheld Assets [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	30,292,552	24,448,486
Fair Value		30,600,795	25,302,488
Amount Presented in the Balance Sheet		30,600,795	25,302,488
AFS | Exclude Life Funds Withheld Assets [Member] | Fixed maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	28,839,622	23,427,432
Fair Value		29,104,486	24,177,469
Amount Presented in the Balance Sheet		29,104,486	24,177,469
AFS | Exclude Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	5,047,621	2,100,851
Fair Value		5,065,637	2,171,953
Amount Presented in the Balance Sheet		5,065,637	2,171,953
AFS | Exclude Life Funds Withheld Assets [Member] | RMBS - Agency
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	3,697,756	3,625,171
Fair Value		3,757,971	3,728,576
Amount Presented in the Balance Sheet		3,757,971	3,728,576
AFS | Exclude Life Funds Withheld Assets [Member] | RMBS - Non-Agency
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	319,876	404,398
Fair Value		328,540	427,351
Amount Presented in the Balance Sheet		328,540	427,351
AFS | Exclude Life Funds Withheld Assets [Member] | CMBS
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	401,713	1,033,819
Fair Value		405,316	1,052,544
Amount Presented in the Balance Sheet		405,316	1,052,544
AFS | Exclude Life Funds Withheld Assets [Member] | Collateralized debt obligations ('CDO') [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	41,679	717,544
Fair Value		32,410	692,034
Amount Presented in the Balance Sheet		32,410	692,034
AFS | Exclude Life Funds Withheld Assets [Member] | Other asset-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	1,164,426	1,028,528
Fair Value		1,168,572	1,065,293
Amount Presented in the Balance Sheet		1,168,572	1,065,293
AFS | Exclude Life Funds Withheld Assets [Member] | U.S. States and political subdivisions of the States [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	2,514,048	1,892,566
Fair Value		2,632,070	2,021,272
Amount Presented in the Balance Sheet		2,632,070	2,021,272
AFS | Exclude Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	5,249,148	4,162,425
Fair Value		5,251,614	4,240,073
Amount Presented in the Balance Sheet		5,251,614	4,240,073
AFS | Exclude Life Funds Withheld Assets [Member] | Equity securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	834,079	763,833
Fair Value		878,919	868,292
Amount Presented in the Balance Sheet		878,919	868,292
AFS | Exclude Life Funds Withheld Assets [Member] | Short-term investments
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	618,851	257,221
Fair Value		617,390	256,727
Amount Presented in the Balance Sheet		617,390	256,727
AFS | Life Funds Withheld Assets [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	2,678,032	4,301,339
Fair Value		3,153,103	5,181,565
Amount Presented in the Balance Sheet		3,153,103	5,181,565
AFS | Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	10,721	14,866
Fair Value		12,742	18,724
Amount Presented in the Balance Sheet		12,742	18,724
AFS | Life Funds Withheld Assets [Member] | RMBS - Agency
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	591	3,301
Fair Value		752	3,782
Amount Presented in the Balance Sheet		752	3,782
AFS | Life Funds Withheld Assets [Member] | RMBS - Non-Agency
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	24,401	71,075
Fair Value		26,953	85,335
Amount Presented in the Balance Sheet		26,953	85,335
AFS | Life Funds Withheld Assets [Member] | CMBS
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	107,968	168,886
Fair Value		122,481	193,167
Amount Presented in the Balance Sheet		122,481	193,167
AFS | Life Funds Withheld Assets [Member] | Other asset-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	132,674	238,168
Fair Value		149,795	273,541
Amount Presented in the Balance Sheet		149,795	273,541
AFS | Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	737,735	1,397,194
Fair Value		933,516	1,789,036
Amount Presented in the Balance Sheet		933,516	1,789,036
Financial Services Sector [Member] | Trading | Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	344,070	0
Fair Value		335,956	0
Amount Presented in the Balance Sheet		335,956	0
Financial Services Sector [Member] | AFS | Exclude Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	3,535,830	2,687,797
Fair Value		3,561,909	2,761,916
Amount Presented in the Balance Sheet		3,561,909	2,761,916
Financial Services Sector [Member] | AFS | Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	531,016	701,587
Fair Value		598,236	801,019
Amount Presented in the Balance Sheet		598,236	801,019
Non-Financial Services Sector [Member] | Trading | Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	509,441	1,180
Fair Value		493,621	1,171
Amount Presented in the Balance Sheet		493,621	1,171
Non-Financial Services Sector [Member] | AFS | Exclude Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	6,867,525	5,774,333
Fair Value		6,900,447	6,016,457
Amount Presented in the Balance Sheet		6,900,447	6,016,457
Non-Financial Services Sector [Member] | AFS | Life Funds Withheld Assets [Member] | Corporate
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost or Amortized Cost	[1]	1,132,926	1,706,262
Fair Value		1,308,628	2,016,961
Amount Presented in the Balance Sheet		$ 1,308,628	$ 2,016,961
[1]	Investments in fixed maturities, short-term investments and held to maturity are shown at amortized cost.

Schedule II - Condensed Fina164

Schedule II - Condensed Financial Information of Registrant - Condensed Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 3,256,236	$ 2,521,814	$ 1,800,832	$ 2,618,378
Other assets	937,199	750,872
Total assets	58,682,938	45,046,819
Liabilities:
Total liabilities	$ 45,028,475	$ 33,611,053
Commitments and Contingencies
Shareholders' equity:
Class A ordinary shares, 999,990,000 authorized, par value $0.01; issued and outstanding (2015, 294,745,045; 2014, 255,182,955)	$ 2,947	$ 2,552
Additional paid in capital	8,910,167	7,359,102
Accumulated other comprehensive income	686,616	1,484,458	$ 736,657	1,520,020
Retained earnings	2,077,349	1,187,639
Shareholders' equity attributable to XL Group plc	11,677,079	10,033,751
Total liabilities and shareholders' equity	$ 58,682,938	$ 45,046,819
Parenthetical information:
Ordinary shares, shares authorized (in shares)	999,990,000	999,990,000
Ordinary shares, par value (in dollars per share)	$ 0.01	$ 0.01
Ordinary shares, shares issued (in shares)	294,745,045	255,182,955
Ordinary shares, shares outstanding (in shares)	294,745,045	255,182,955	278,253,000
XL Group PLC
ASSETS
Cash and cash equivalents	$ 11,557	$ 22,443	$ 12,709	$ 10,961
Amounts due from subsidiaries	33,417	0
Investments in subsidiaries on an equity basis	11,648,673	10,195,445
Other assets	2,748	3,017
Total assets	11,696,395	10,220,905
Liabilities:
Amounts due to subsidiaries	0	166,782
Accounts payable and accrued liabilities	19,316	20,372
Total liabilities	$ 19,316	$ 187,154
Commitments and Contingencies
Shareholders' equity:
Class A ordinary shares, 999,990,000 authorized, par value $0.01; issued and outstanding (2015, 294,745,045; 2014, 255,182,955)	$ 2,947	$ 2,552
Additional paid in capital	8,910,167	7,359,102
Accumulated other comprehensive income	686,616	1,484,458
Retained earnings	2,077,349	1,187,639
Shareholders' equity attributable to XL Group plc	11,677,079	10,033,751
Total liabilities and shareholders' equity	$ 11,696,395	$ 10,220,905
Parenthetical information:
Ordinary shares, shares authorized (in shares)	999,990,000	999,990,000
Ordinary shares, par value (in dollars per share)	$ 0.01	$ 0.01
Ordinary shares, shares issued (in shares)	294,745,045	255,182,955
Ordinary shares, shares outstanding (in shares)	294,745,045	255,182,955

Schedule II - Condensed Fina165

Schedule II - Condensed Financial Information of Registrant - Statement of Income and Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements Captions [Line Items]
Net investment income									$ 872,370	$ 918,625	$ 957,716
Total revenues									9,308,926	6,602,267	7,541,234
Operating expenses									1,966,939	1,341,315	1,213,178
Foreign exchange (gains) losses									22,504	(37,568)	(28,243)
Interest expense									205,215	134,106	155,462
Total expenses									8,399,895	6,343,750	6,446,886
Provision for income tax									(19,161)	96,897	77,505
Net income (loss) attributable to ordinary shareholders									1,207,152	188,340	1,059,916
Net income (loss)	$ 228,550	$ 27,282	$ 915,039	$ 36,281	$ 139,499	$ 72,384	$ (279,260)	$ 255,717
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax									0	424,861	0
Cumulative adjustments recorded to value of future policy benefit reserves, amount									170,688	(400,456)	(44,660)
Change in net unrealized gains (losses) on affiliate and other investments, net of tax									(6,074)	35,143	26,637
Change in OTTI losses recognized in other comprehensive income, net of tax									18,545	13,143	32,181
Change in underfunded pension liability									(3,852)	(7,550)	7,653
Change in value of cash flow hedge									(200)	255	439
Foreign currency translation adjustments									(25,315)	(25,729)	(54,858)
Comprehensive income (loss)									409,310	936,141	276,553
XL Group PLC
Condensed Financial Statements Captions [Line Items]
Net investment income									169	275	24
Total revenues									169	275	24
Operating expenses									46,340	9,646	11,699
Foreign exchange (gains) losses									(345)	127	243
Interest expense									11	5	2
Total expenses									46,006	9,778	11,944
Income (loss) before income tax									(45,837)	(9,503)	(11,920)
Equity in net earnings (losses) of subsidiaries (dividends were: 2015: $764,277; 2014: $858,521; 2013: $617,719)									1,253,609	197,843	1,071,836
Provision for income tax									620	0	0
Net income (loss) attributable to ordinary shareholders									1,207,152	188,340	1,059,916
Net income (loss)									1,207,152	188,340	1,059,916
Unrealized gains on held to maturity investment portfolio at time of transfer to available for sale, net of tax									0	424,861	0
Change in net unrealized gains (losses) on affiliate and other investments, net of tax									(6,074)	35,143	26,637
Change in OTTI losses recognized in other comprehensive income, net of tax									18,545	13,143	32,181
Change in underfunded pension liability									(3,852)	(7,550)	7,653
Change in value of cash flow hedge									(200)	255	439
Foreign currency translation adjustments									(25,315)	(25,729)	(54,858)
Comprehensive income (loss)									409,310	936,141	276,553
Parenthetical information, dividends:
Dividends received from subsidiaries									764,277	858,521	617,719
Dividends and Return of Capital Received From Subsidiary									829,000	940,000	702,000
Life Funds Withheld Assets [Member]
Condensed Financial Statements Captions [Line Items]
Net investment income									187,489	129,575	0
Change in net unrealized gains (losses) on investments, net of tax									(421,604)	274,083	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									(421,604)	274,083	0
Exclude Life Funds Withheld Assets [Member]
Condensed Financial Statements Captions [Line Items]
Net investment income									684,881	789,050	957,716
Change in net unrealized gains (losses) on investments, net of tax									(530,030)	434,051	(750,755)
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									(530,030)	434,051	(750,755)
Unrealized Gains (Losses) on Investments
Condensed Financial Statements Captions [Line Items]
Cumulative adjustments recorded to value of future policy benefit reserves, amount									170,700
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									$ 170,688	$ (400,456)	$ (44,660)

Schedule II - Condensed Fina166

Schedule II - Condensed Financial Information of Registrant - Statement of Cash Flows (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements Captions [Line Items]
Net income (loss) attributable to ordinary shareholders		$ 1,207,152	$ 188,340	$ 1,059,916
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Share based compensation		74,431	81,287	46,489
Other		26,968	5,447	9,702
Total adjustments		(697,783)	694,346	(356,670)
Net cash provided by (used in) operating activities		615,556	963,184	779,977
Cash flows provided by (used in) investing activities: [Abstract]
Purchase of Catlin Group Limited, net of acquired cash		(1,020,015)	0	0
Proceeds from sale of life reinsurance subsidiary		0	570,000	0
Net cash provided by (used in) investing activities		136,432	1,711,621	(1,197,862)
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options		9,976	6,367	12,623
Dividends paid		(208,516)	(169,620)	(160,155)
Buybacks of ordinary shares		(468,971)	(801,953)	(675,617)
Net cash provided by (used in) financing activities		46,811	(1,863,708)	(394,843)
Net change in cash and cash equivalents		734,422	720,982	(817,546)
Cash and cash equivalents – beginning of period		2,521,814	1,800,832	2,618,378
Cash and cash equivalents – end of period		3,256,236	2,521,814	1,800,832
XL Group PLC
Condensed Financial Statements Captions [Line Items]
Net income (loss) attributable to ordinary shareholders		1,207,152	188,340	1,059,916
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in (earnings) loss of subsidiaries		(1,253,609)	(197,843)	(1,071,836)
Share based compensation	[1]	74,431	81,287	46,489
Amounts due to (from) subsidiaries		(200,199)	(23,819)	104,590
Dividends received from subsidiaries		764,277	858,521	617,719
Other		(30,584)	(10,632)	(16,570)
Total adjustments		(645,684)	707,514	(319,608)
Net cash provided by (used in) operating activities		561,468	895,854	740,308
Cash flows provided by (used in) investing activities: [Abstract]
Purchase of Catlin Group Limited, net of acquired cash		(2,287,579)	0	0
Proceeds from sale of life reinsurance subsidiary		2,317,699	0	0
Returns of capital from subsidiaries		65,037	79,086	84,589
Net cash provided by (used in) investing activities		95,157	79,086	84,589
Cash flows provided by (used in) financing activities:
Proceeds from issuance of ordinary shares and exercise of stock options		9,976	6,367	12,623
Dividends paid		(208,516)	(169,620)	(160,155)
Buybacks of ordinary shares		(468,971)	(801,953)	(675,617)
Net cash provided by (used in) financing activities		(667,511)	(965,206)	(823,149)
Net change in cash and cash equivalents		(10,886)	9,734	1,748
Cash and cash equivalents – beginning of period		22,443	12,709	10,961
Cash and cash equivalents – end of period		11,557	22,443	12,709
Cash collected from subsidiaries [Member] | XL Group PLC
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Share based compensation		$ 60,100	$ 59,200	$ 33,900
[1]	Includes cash collected from subsidiaries in the amounts of $60.1 million, $59.2 million and $33.9 million, respectively, for the years ended December 31, 2015, 2014 and 2013.

Schedule IV - Reinsurance (Deta

Schedule IV - Reinsurance (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Life reinsurance in force:
Gross amount, life reinsurance in force	[1]	$ 0	$ 0	$ 0
Ceded to other companies, life reinsurance in force	[1]	62,290,992	46,947,677	378,391
Assumed from other companies, life reinsurance in force	[1]	63,158,304	68,854,340	77,917,632
Net amount, life reinsurance in force	[1]	867,312	$ 21,906,663	$ 77,539,241
Percentage of amount assumed to net, life reinsurance in force	[1]		314.30%	100.50%
Total premiums earned:
Gross amount, premiums earned		7,717,173	$ 5,173,403	$ 4,966,207
Ceded to other companies, premiums earned		3,266,085	1,955,098	1,344,289
Assumed from other companies, premiums earned		3,775,337	2,676,765	2,687,603
Net amount, premiums earned		$ 8,226,425	$ 5,895,070	$ 6,309,521
Percentage of amount assumed to net		45.90%	45.40%	42.60%
Property and casualty operations
Total premiums earned:
Gross amount, premiums earned		$ 7,717,173	$ 5,173,403	$ 4,966,207
Ceded to other companies, premiums earned		3,018,410	1,799,294	1,315,369
Assumed from other companies, premiums earned		3,465,421	2,343,329	2,363,261
Net amount, premiums earned		$ 8,164,184	$ 5,717,438	$ 6,014,099
Percentage of amount assumed to net		42.40%	41.00%	39.30%
Life operations
Total premiums earned:
Gross amount, premiums earned		$ 0	$ 0	$ 0
Ceded to other companies, premiums earned		247,675	155,804	28,920
Assumed from other companies, premiums earned		309,916	333,436	324,342
Net amount, premiums earned		$ 62,241	$ 177,632	$ 295,422
Percentage of amount assumed to net		497.90%	187.70%	109.80%
[1]	Represents the sum face value outstanding of the in force life reinsurance policies.

Schedule VI - Supplementary 168

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Losses and loss expenses incurred related to - current year	$ 5,072,830	$ 3,513,465	$ 4,021,353
Losses and loss expenses incurred related to - prior year	(306,630)	(255,072)	(289,889)
P&C Operations
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred acquisition costs	893,111	357,067	537,473
Reserves for losses and loss expenses	25,439,744	19,353,243	20,481,065
Reserves for unearned premiums	7,043,383	3,973,159	3,846,568
Net earned premiums	8,164,184	5,717,438	6,014,099
Net investment income	644,312	642,492	671,071
Losses and loss expenses incurred related to - current year	5,072,830	3,513,465	4,021,353
Losses and loss expenses incurred related to - prior year	(306,630)	(255,072)	(289,889)
Net paid losses and loss expenses	5,374,652	3,821,335	3,828,139
Amortization of deferred acquisition costs	1,306,654	724,003	882,658
Net premiums written	$ 7,888,824	$ 5,767,209	$ 5,903,982