Allied World Assurance 10-Q 21 Jul 16 2016 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 13, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Allied World Assurance Co Holdings, AG
Entity Central Index Key	1,163,348
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		87,348,066

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
ASSETS:
Fixed maturity investments trading, at fair value (amortized cost: 2016: $7,769.0; 2015: $7,290.6)	$ 7,794.2	$ 7,201.5
Equity securities trading, at fair value (cost: 2016: $205.3; 2015: $395.3)	202.3	403
Other invested assets	939.8	966.7
Total investments	8,936.3	8,571.2
Cash and cash equivalents	584.5	608
Restricted cash	78.2	60.6
Insurance balances receivable	961	745.9
Funds held	279.1	640.8
Prepaid reinsurance	430.1	392.3
Reinsurance recoverable	1,516.7	1,480
Reinsurance recoverable on paid losses	73.8	96.4
Accrued investment income	38.7	38.3
Net deferred acquisition costs	168.9	165.2
Goodwill	392.6	388.1
Intangible assets	113.5	116.6
Balances receivable on sale of investments	114.6	36.9
Net deferred tax assets	21.2	24.4
Other assets	158.1	147.2
Total assets	13,867.3	13,511.9
LIABILITIES:
Reserve for losses and loss expenses	6,623.2	6,456.2
Unearned premiums	1,822.1	1,683.3
Reinsurance balances payable	227.7	214.4
Balances due on purchases of investments	155	125.1
Senior notes:
Principal amount	1,300	1,300
Less unamortized discount and debt issuance costs	6.3	7.1
Senior notes, net of unamortized discount and debt issuance costs	1,293.7	1,292.9
Other long-term debt	23.1	23
Accounts payable and accrued liabilities	138	184.5
Total liabilities	10,282.8	9,979.4
SHAREHOLDERS’ EQUITY:
Common shares: 2016 and 2015: par value CHF 4.10 per share (2016: 93,586,418; 2015: 95,523,230 shares issued and 2016: 87,463,950; 2015: 90,959,635 shares outstanding)	366.7	386.7
Treasury shares, at cost (2016: 6,122,468; 2015: 4,563,595)	(216.7)	(155.1)
Accumulated other comprehensive loss	(6)	(9.3)
Retained earnings	3,440.5	3,310.2
Total shareholders’ equity	3,584.5	3,532.5
Total liabilities and shareholders’ equity	$ 13,867.3	$ 13,511.9

Unaudited Condensed Consolidat3

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) $ in Millions	Jun. 30, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Fixed maturity investments trading, amortized cost | $	$ 7,769	$ 7,290.6
Equity securities trading, cost | $	$ 205.3	$ 395.3
Common stock, shares issued	93,586,418	95,523,230
Common stock, shares outstanding	87,463,950	90,959,635
Treasury stock (shares)	6,122,468	4,563,595

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements Of Operations And Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
REVENUES:
Gross premiums written	$ 800.3	$ 826	$ 1,663.8	$ 1,706.6
Premiums ceded	(222.2)	(222.3)	(381.7)	(330.4)
Net premiums written	578.1	603.7	1,282.1	1,376.2
Change in unearned premiums	24.8	42.7	(99.1)	(161.3)
Net premiums earned	602.9	646.4	1,183	1,214.9
Net investment income	55.8	42.8	109.1	87.3
Net realized investment gains (losses)	74.5	(20.2)	93.4	24.8
Other income	5.2	0.9	5.7	1.9
Total revenues	738.4	669.9	1,391.2	1,328.9
EXPENSES:
Net losses and loss expenses	365.4	431.5	737.8	756.7
Acquisition costs	87.4	100.6	175.7	179.3
General and administrative expenses	104.7	108.4	201.1	205.5
Other expenses	1.7	1.2	2.8	3.1
Amortization of intangible assets	2.5	2.8	5	3.4
Interest expense	19.9	14.5	39.8	28.8
Foreign exchange (gain) loss	(2.9)	1.3	(5.9)	11.2
Total expenses	578.7	660.3	1,156.3	1,188
Income before income taxes	159.7	9.6	234.9	140.9
Income tax expense	6.3	0.1	7.4	7.1
NET INCOME	153.4	9.5	227.5	133.8
Other comprehensive gain (loss): foreign currency translation adjustment	0.1	(3.3)	3.3	(3.3)
COMPREHENSIVE INCOME	$ 153.5	$ 6.2	$ 230.8	$ 130.5
PER SHARE DATA
Basic earnings per share	$ 1.73	$ 0.10	$ 2.54	$ 1.42
Diluted earnings per share	$ 1.70	$ 0.10	$ 2.50	$ 1.40
Weighted average common shares outstanding	88,742,484	92,441,730	89,495,564	94,178,989
Weighted average common shares and common share equivalents outstanding	90,040,509	93,984,226	90,830,814	95,830,455
Dividends paid per share	$ 0.26	$ 0.225	$ 0.52	$ 0.45

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements Of Shareholders' Equity - USD ($) $ in Millions	Total	Common shares	Treasury Shares	Accumulated Other Comprehensive Income	Retained Earnings
Balance, at beginning of period at Dec. 31, 2014	$ 3,778.2	$ 408	$ (143.1)	$ 0	$ 3,513.3
Net income	133.8				133.8
Dividends	(45.1)				(45.1)
Stock compensation	6.4		15.5		(9.1)
Share repurchases	(245.3)		(245.3)
Shares cancelled	0	(21.3)	213.7		(192.4)
Foreign currency translation adjustment	(3.3)			(3.3)
Balance, at end of period at Jun. 30, 2015	3,624.7	386.7	(159.2)	(3.3)	3,400.5
Balance, at beginning of period at Dec. 31, 2015	3,532.5	386.7	(155.1)	(9.3)	3,310.2
Net income	227.5				227.5
Dividends	(46.2)				(46.2)
Stock compensation	7.4		11.7		(4.3)
Share repurchases	(140)		(140)
Shares cancelled	0	(20)	66.7		(46.7)
Foreign currency translation adjustment	3.3			3.3
Balance, at end of period at Jun. 30, 2016	$ 3,584.5	$ 366.7	$ (216.7)	$ (6)	$ 3,440.5

Unaudited Condensed Consolidat6

Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 227.5	$ 133.8
Adjustments to reconcile net income to cash provided by operating activities:
Net realized gains on sales of investments	(31.2)	(58.2)
Mark to market adjustments	(89.3)	35.6
Stock compensation expense	8.6	7.9
Undistributed income of equity method investments	15.2	16
Changes in:
Reserve for losses and loss expenses, net of reinsurance recoverables	130.2	132.9
Unearned premiums, net of prepaid reinsurance	101	160.4
Insurance balances receivable	(216.4)	(162.3)
Reinsurance recoverable on paid losses	22.6	(2.3)
Funds held	361.7	261.5
Reinsurance balances payable	13.3	11.5
Net deferred acquisition costs	(3.7)	(17.6)
Net deferred tax assets	3.2	(2.7)
Accounts payable and accrued liabilities	(47.9)	(54.6)
Other items, net	5.2	(34.5)
Net cash provided by operating activities	500	427.4
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	(3,257.8)	(2,854.8)
Purchases of other invested assets	(33.2)	(73.1)
Sales of trading securities	2,932.2	2,953.6
Sales of other invested assets	37.3	85.5
Purchases of fixed assets	(1.9)	(18)
Change in restricted cash	(17.6)	(26.1)
Net cash paid for acquisitions	(1.2)	(141.5)
Net cash used in investing activities	(342.2)	(74.4)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	(46.2)	(43.2)
Proceeds from the exercise of stock options	3.1	7.4
Share repurchases	(139.5)	(246.4)
Proceeds from other long-term debt	0	3.9
Repayment of other long-term debt	(0.2)	0
Net cash used in financing activities	(182.8)	(278.3)
Effect of exchange rate changes on foreign currency cash	1.5	(2.2)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(23.5)	72.5
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	608	589.3
CASH AND CASH EQUIVALENTS, END OF PERIOD	584.5	661.8
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1.6	1.9
Cash paid for interest expense	$ 37.9	$ 27

General

General	6 Months Ended
	Jun. 30, 2016
General [Abstract]
General	GENERAL Allied World Assurance Company Holdings, AG, a Swiss holding company (“Allied World Switzerland”), through its wholly-owned subsidiaries (collectively, the “Company”), is a global provider of a diversified portfolio of property and casualty insurance and reinsurance. References to “$” are to the lawful currency of the United States and to “CHF” are to the lawful currency of Switzerland.

Basis of Preparation and Consol

Basis of Preparation and Consolidation	6 Months Ended
	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Preparation and Consolidation	BASIS OF PREPARATION AND CONSOLIDATION These unaudited condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with Article 10 of Regulation S-X as promulgated by the U.S. Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, these unaudited condensed consolidated financial statements reflect all adjustments that are normal and recurring in nature and necessary for a fair presentation of financial position and results of operations as of the end of and for the periods presented. The results of operations for any interim period are not necessarily indicative of the results for a full year. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts 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. Actual results could differ from those estimates. The significant estimates reflected in the Company’s financial statements, include, but are not limited to: • The premium estimates for certain reinsurance agreements, • Recoverability of deferred acquisition costs, • The reserve for outstanding losses and loss expenses, • Valuation of ceded reinsurance recoverables, • Determination of impairment of goodwill and other intangible assets, and • Valuation of financial instruments. Intercompany accounts and transactions have been eliminated on consolidation and all entities meeting consolidation requirements have been included in the unaudited condensed consolidated financial statements. To facilitate comparison of information across periods, certain reclassifications have been made to prior year amounts to conform to the current year's presentation. These unaudited condensed consolidated financial statements, including these notes, should be read in conjunction with the Company’s audited consolidated financial statements, and related notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 .

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”). ASU 2014-09 provides a framework, through a five-step process, for recognizing revenue from customers, improves comparability and consistency of recognizing revenue across entities, industries, jurisdictions and capital markets, and requires enhanced disclosures. Certain contracts with customers are specifically excluded from the scope of ASU 2014-09, including, among others, insurance contracts accounted for under Accounting Standard Codification 944, Financial Services - Insurance . ASU 2014-09 is effective on January 1, 2017 with retrospective adoption required for the comparative periods. With the issuance of Accounting Standards Update 2015-14, “Revenue from Contracts with Customers (Topic 606) - Deferral of the Effective Date”, this standard will be effective on January 1, 2018 with retrospective adoption required for the comparative periods. The Company is currently assessing the impact the adoption of ASU 2014-09 will have on future financial statements and related disclosures. In May 2015, the FASB issued Accounting Standards Update 2015-09, “Financial Services - Insurance (Topic 944): Disclosures about Short-Duration Contracts” (“ASU 2015-09”). ASU 2015-09 provides enhanced disclosures, on an annual basis, related to the reserve for losses and loss expenses. The enhanced disclosures required by ASU 2015-09 include (1) net incurred and paid claims development information by accident year, (2) a reconciliation of incurred and paid claims development information to the aggregate carrying amount of the reserve for losses and loss expenses, (3) for each accident year presented of incurred claims development information, the total of reserves for losses incurred but not reported (“IBNR”), including expected development on reported claims, included in the reserve for losses and loss expenses and a description of the reserving methodologies and changes to the reserving methodologies, and (4) for each accident year presented of incurred claims development information, quantitative information about claims frequency, as well as a description of methodologies used for determining claim frequency information. ASU 2015-09 is effective for annual periods beginning after December 15, 2015, and as such the disclosures will first be presented in the Company's Annual Report on Form 10-K for the year ended December 31, 2016. The Company is currently assessing the impact the adoption of ASU 2015-09 will have on future disclosures. In January 2016, the FASB issued Accounting Standards Update 2016-01, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” (“ASU 2016-01”). ASU 2016-01 changes current U.S. GAAP for public entities by requiring the following, among others: (1) equity securities, except 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) the use of the exit price when measuring fair value of financial instruments for disclosure purposes; (3) 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; and (4) separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or notes to the financial statements. ASU 2016-01 is effective for annual periods beginning after January 1, 2018, including interim periods. Early application is permitted. The Company is currently assessing the impact the adoption of ASU 2016-01 will have on future financial statements and disclosures. In February 2016, the FASB issued Accounting Standards Update 2016-02, “Leases” (“ASU 2016-02”). ASU 2016-02 changes current U.S. GAAP for lessees to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous GAAP. ASU 2016-02 is effective for annual periods beginning after January 1, 2019, including interim periods. Early application is permitted. The Company is currently assessing the impact the adoption of ASU 2016-02 will have on future financial statements and disclosures. I n March 2016, the FASB issued Accounting Standards Update 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU 2016-09”). ASU 2016-09 modifies U.S. GAAP by requiring the following, among others: (1) all excess tax benefits and tax deficiencies are to be recognized as income tax expense or benefit on the income statement (excess tax benefits are recognized regardless of whether the benefit reduces taxes payable in the current period); (2) excess tax benefits are to be classified along with other income tax cash flows as an operating activity in the statement of cash flows; (3) in the area of forfeitures, an entity can still follow the current U.S. GAAP practice of making an entity-wide accounting policy election to estimate the number of awards that are expected to vest or may instead account for forfeitures when they occur; and (4) classification as a financing activity in the statement of cash flows of cash paid by an employer to the taxing authorities when directly withholding shares for tax withholding purposes. ASU 2016-09 is effective for annual periods beginning after January 1, 2017, including interim periods. Early application is permitted. The Company is currently assessing the impact the adoption of ASU 2016-09 will have on future financial statements and disclosures. In June 2016, the FASB issued Accounting Standards Update 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (“ASU 2016-13”). ASU 2016-13 modifies U.S. GAAP related to the recognition of credit losses by replacing the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 would apply to financial assets such as loans, debt securities, trade receivables, off-balance sheet credit exposures, reinsurance receivables, and other financial assets that have the contractual right to receive cash. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The Company's invested assets are measured at fair value through net income, and therefore those invested assets would not be required to record a credit loss. The Company has other financial assets, such as reinsurance receivables, that could be impacted by the adoption of ASU 2016-13. ASU 2016-13 is effective for annual periods beginning after January 1, 2020, including interim periods. The Company is currently assessing the impact the adoption of ASU 2016-13 will have on future financial statements and disclosures.

Investments

Investments	6 Months Ended
	Jun. 30, 2016
Investments [Abstract]
Investments	INVESTMENTS a) Trading Securities Securities accounted for at fair value with changes in fair value recognized in the unaudited condensed consolidated statements of operations and comprehensive income (the “consolidated income statements”) by category are as follows: June 30, 2016 December 31, 2015 Fair Value Amortized Cost Fair Value Amortized Cost U.S. government and government agencies $ 1,805.5 $ 1,792.2 $ 1,434.0 $ 1,437.9 Non-U.S. government and government agencies 469.6 479.8 556.8 579.2 States, municipalities and political subdivisions 504.6 476.4 413.5 396.0 Corporate debt: Financial institutions 1,223.6 1,205.8 1,275.4 1,277.3 Industrials 1,476.8 1,461.5 1,308.1 1,345.6 Utilities 140.4 140.3 118.9 125.4 Mortgage-backed Agency mortgage-backed 757.0 742.1 751.8 745.4 Non-agency residential mortgage-backed 24.0 23.1 34.0 32.4 Commercial mortgage-backed 604.2 637.0 582.8 600.1 Asset-backed 788.5 810.8 726.2 751.1 Total fixed maturity investments $ 7,794.2 $ 7,769.0 $ 7,201.5 $ 7,290.6 June 30, 2016 December 31, 2015 Fair Value Original Cost Fair Value Original Cost Equity securities $ 202.3 $ 205.3 $ 403.0 $ 395.3 Other invested assets 820.0 767.0 840.2 770.9 $ 1,022.3 $ 972.3 $ 1,243.2 $ 1,166.2 Other invested assets, included in the table above, include investments in private equity funds, hedge funds and a high yield loan fund that are accounted for at fair value, but excludes other private securities described below in Note 4(b) that are accounted for using the equity method of accounting. b) Other Invested Assets Details regarding the carrying value, redemption characteristics and unfunded investment commitments of the other invested assets portfolio as of June 30, 2016 and December 31, 2015 were as follows: Investment Type Carrying Value as of June 30, 2016 Investments Estimated Investments Redemption (1) Redemption (1) Unfunded Private equity (primary and secondary) $ 248.8 $ 248.8 1 - 7 Years $ — $ 245.7 Levered credit 218.4 218.4 4 - 8 Years — 200.6 Real estate 25.3 25.3 7 - 9 Years — 189.3 Distressed 5.1 5.1 2 Years — 3.8 Total private equity 497.6 497.6 — 639.4 Distressed 168.5 0.1 2 Years 168.4 Monthly 90 Days — Relative value credit 81.8 — 81.8 Quarterly 60 Days — Equity long/short 62.2 — 62.2 Quarterly 45 Days — Fund of funds 9.9 — 9.9 Annual 60 Days — Total hedge funds 322.4 0.1 322.3 — Total other invested assets at fair value 820.0 497.7 322.3 639.4 Other private securities 119.8 — 119.8 — Total other invested assets $ 939.8 $ 497.7 $ 442.1 $ 639.4 Investment Type Carrying Value as of December 31, 2015 Investments Estimated Investments Redemption (1) Redemption (1) Unfunded Private equity (primary and secondary) $ 236.4 $ 236.4 1 - 7 Years $ — $ 231.0 Levered credit 205.9 205.9 4 - 8 Years — 179.0 Distressed 5.1 5.1 2 Years — 3.8 Real estate — — 7 - 9 Years — 200.0 Total private equity 447.4 447.4 — 613.8 Distressed 215.6 54.6 2 Years 161.0 Monthly 90 Days — Equity long/short 58.0 — 58.0 Quarterly 45 Days — Relative value credit 105.4 — 105.4 Quarterly 60 Days — Total hedge funds 379.0 54.6 324.4 — High yield loan fund 13.8 — 13.8 Monthly 30 days — Total other invested assets at fair value 840.2 502.0 338.2 613.8 Other private securities 126.5 — 126.5 — Total other invested assets $ 966.7 $ 502.0 $ 464.7 $ 613.8 _______________________ (1) The redemption frequency and notice periods only apply to the investments without redemption restrictions. Some or all of these investments may be subject to a gate as described below. In general, the Company has invested in hedge funds that 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 lock-up periods ranging from one to three years from initial investment. A lock-up period refers to the initial amount of time an investor is contractually required to invest before having the ability to redeem. Funds that provide for periodic redemptions may, depending on the funds’ governing documents, have the ability to deny or delay a redemption request, called a “gate.” The fund may implement this restriction if the aggregate amount of redemption requests as of a particular date exceeds a specified level, generally ranging from 15% to 25% of the fund’s net assets. The gate is a method for executing an orderly redemption process to reduce the possibility of adversely affecting investors in the fund. Typically, the imposition of a gate delays a portion of the requested redemption, with the remaining portion settled in cash sometime after the redemption date. Certain funds may impose a redemption fee on early redemptions. Interests in private equity funds cannot be redeemed because the investments include restrictions that do not allow for redemption until termination of the fund. The following describes each investment type: • Private equity (primary and secondary): Primary equity funds includes funds that may invest in companies and general partnership interests, as well as direct investments. Secondary funds buy limited partnership interests from existing limited partners of primary private equity funds. As owners of private equity, funds may seek liquidity by selling their existing interests, plus any remaining commitment, to secondary market participants. These funds cannot be redeemed because the investments include restrictions that do not allow for redemption until termination of the funds. • Levered credit (including mezzanine debt): Levered credit funds invest across the capital structures of upper middle market and middle market companies in connection with leveraged buyouts, mergers and acquisitions, recapitalizations, growth financings, refinancings and other corporate purposes. The most common position in the capital structure of mezzanine funds will be between the senior secured debt holder and the equity; however, the funds in which we are invested may include secured debt, subordinated debt, preferred stock and/or private equity. These funds cannot be redeemed because the investments include restrictions that do not allow for redemption until termination of the funds. • Real estate funds: Private real estate funds invest directly (through debt and equity) in commercial real estate (multifamily, industrial, office, student housing and retail) as well as residential property. Real estate managers have diversified portfolios that generally follow core, core-plus, value-added or opportunistic strategies. These funds cannot be redeemed because the investments include restrictions that do not allow for redemption until termination of the funds. • Distressed funds: In distressed debt investing, managers take positions in the debt of companies experiencing significant financial difficulties, including bankruptcy, or in certain positions of the capital structure of structured securities. The manager relies on the fundamental analysis of these securities, including the claims on the assets and the likely return to bondholders. Certain funds cannot be redeemed because the investments include restrictions that do not allow for redemption until termination of the funds. • Relative value credit funds: These funds seek to take exposure to credit-sensitive securities, long and/or short, based upon credit analysis of issuers and securities and credit market views. • Equity long/short funds: In equity long/short funds, managers take long positions in companies they deem to be undervalued and short positions in companies they deem to be overvalued. Long/short managers may invest in countries, regions or sectors and vary by their use of leverage and by their targeted net long position. • Fund of funds: Fund of funds allocate assets among multiple investment managers unaffiliated with the fund of funds sponsor employing a variety of proprietary investment strategies. Fund of funds strategies will invest in a portfolio of funds that primarily pursue the following investment strategies: equity, macro, event driven and credit. • High yield loan fund: A long-only private mutual fund that invests in high yield fixed income securities. • Other private securities: These securities mostly include strategic non-controlling minority investments in private asset management companies and other insurance related investments that are accounted for using the equity method of accounting. Unconsolidated Variable Interest Entities As a result of the adoption of Accounting Standards Update 2015-02, “Amendments to the Consolidation Analysis”, which became effective January 1, 2016, certain limited partnership investments and similar legal entity investments were considered variable interest entities (“VIEs”) as there were no substantive kick-out or other participating rights. These VIEs will not be consolidated because the Company has determined it is not considered the primary beneficiary, as it does not have both the power to direct the activities that most significantly impact the economic performance of the entity and the obligation to absorb losses of the entity that could be potentially significant to the VIE or the right to receive benefits from the entity that could be potentially significant. As such, the Company continues to record its interests in these entities at fair value, with changes in fair value recorded in the consolidated income statements. The Company's interests in these entities are recorded in “other invested assets” in the unaudited condensed consolidated balance sheets (“consolidated balance sheets”). The Company's maximum exposure to loss in these entities, which is the sum of the carrying value and the unfunded commitment, was $984.8 million as of June 30, 2016 . c) Net Investment Income Three Months Ended Six Months Ended 2016 2015 2016 2015 Fixed maturity investments $ 48.9 $ 41.2 $ 96.9 $ 77.4 Equity securities 1.4 4.9 3.3 8.4 Other invested assets: hedge funds and private equity 7.6 4.6 12.3 13.0 Other invested assets: other private securities 1.7 (3.8 ) 4.7 (2.9 ) Cash and cash equivalents 0.8 0.4 1.3 0.9 Expenses (4.6 ) (4.5 ) (9.4 ) (9.5 ) Net investment income $ 55.8 $ 42.8 $ 109.1 $ 87.3 The loss from “other invested assets: other private securities” for the three and six months ended June 30, 2015 included an other-than-temporary impairment of $6.3 million related to one of the Company's equity method investments. The Company recorded the other-than-temporary impairment as the fair value of this investment was below its carrying value. d) Components of Realized Gains and Losses Three Months Ended Six Months Ended 2016 2015 2016 2015 Gross realized gains on sale of invested assets $ 46.1 $ 36.1 $ 100.2 $ 81.4 Gross realized losses on sale of invested assets (26.9 ) (10.1 ) (68.7 ) (23.1 ) Net realized and unrealized gains (losses) on derivatives 0.1 13.9 (22.9 ) 2.3 Mark-to-market gains (losses): Fixed maturity investments, trading 55.4 (52.7 ) 117.7 (27.2 ) Equity securities, trading 0.9 (0.3 ) (14.2 ) 5.1 Other invested assets, trading (1.1 ) (7.1 ) (18.7 ) (13.7 ) Net realized investment gains (losses) $ 74.5 $ (20.2 ) $ 93.4 $ 24.8 e) Pledged Assets As of June 30, 2016 and December 31, 2015 , $2,873.4 million and $2,748.9 million , respectively, of cash and cash equivalents and investments were deposited, pledged or held in trust accounts in favor of ceding companies and other counterparties or government authorities to comply with reinsurance contract provisions, insurance laws and other contract provisions. In addition, as of June 30, 2016 and December 31, 2015 , a further $587.1 million and $579.3 million , respectively, of cash and cash equivalents and investments were pledged as collateral for the Company’s letter of credit facilities. In June 2016, the Company entered into a $200.0 million committed unsecured credit facility with a syndication of lenders (the “Credit Agreement”). The Credit Agreement provides for a $200.0 million five -year senior unsecured revolving credit facility (the “Facility”) for the making of revolving loans and short-term swingline loans. The aggregate commitment of $200.0 million under the Facility may be increased by up to $150.0 million upon the Company's request and upon the agreement of one or more lenders or additional lenders. The Facility replaces the four-year senior secured credit facility under the Amended and Restated Credit Agreement, dated as of June 7, 2012. In addition, see Note 11(g) to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 for further details on the Company’s credit facilities.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS As of June 30, 2016 and December 31, 2015 , none of the Company’s derivatives were designated as hedges for accounting purposes. The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheets: June 30, 2016 December 31, 2015 Asset Derivative Notional Amount Asset Derivative Fair Value Liability Derivative Notional Amount Liability Derivative Fair Value Asset Derivative Notional Amount Asset Derivative Fair Value Liability Derivative Notional Amount Liability Derivative Fair Value Foreign exchange contracts $ 83.4 $ 1.5 $ 48.6 $ 0.4 $ 41.1 $ 0.1 $ 244.8 $ 3.0 Interest rate swaps — — — — — — 328.2 0.5 Total derivatives $ 83.4 $ 1.5 $ 48.6 $ 0.4 $ 41.1 $ 0.1 $ 573.0 $ 3.5 Derivative assets and derivative liabilities are classified within “other assets” or “accounts payable and accrued liabilities” on the consolidated balance sheets. As of June 30, 2016, all open interest rate swap contracts were closed-out. The following table provides the net realized and unrealized gains (losses) on derivatives not designated as hedges recorded on the consolidated income statements: Three Months Ended Six Months Ended 2016 2015 2016 2015 Foreign exchange contracts $ 3.3 $ 1.2 $ 1.1 $ (6.2 ) Total included in foreign exchange (gain) loss 3.3 1.2 1.1 (6.2 ) Foreign exchange contracts (0.4 ) (0.3 ) (15.3 ) 0.8 Interest rate swaps 0.5 14.2 (7.6 ) 1.5 Total included in net realized investment gains (losses) 0.1 13.9 (22.9 ) 2.3 Total realized and unrealized gains (losses) on derivatives $ 3.4 $ 15.1 $ (21.8 ) $ (3.9 ) Derivative Instruments Not Designated as Hedging Instruments The Company is exposed to foreign currency risk in its investment portfolio. Accordingly, the fair values of the Company’s investment portfolio are partially influenced by the change in foreign exchange rates. These foreign currency hedging activities have not been designated as specific hedges for financial reporting purposes. The Company’s insurance and reinsurance subsidiaries and branches operate in various foreign countries and consequently the Company’s underwriting portfolio is exposed to foreign currency risk. The Company manages foreign currency risk by seeking to match liabilities under the insurance policies and reinsurance contracts that it writes and that are payable in foreign currencies with cash and investments that are denominated in such currencies. When necessary, the Company may also use derivatives to economically hedge un-matched foreign currency exposures, specifically forward contracts and currency options. The Company also purchases and sells interest rate future and interest rate swap contracts to actively manage the duration and yield curve positioning of its fixed income portfolio. Interest rate futures and interest rate swaps can efficiently increase or decrease the overall duration of the portfolio. Additionally, interest rate future and interest rate swap contracts can be utilized to obtain the desired position along the yield curve in order to protect against certain future yield curve shapes. The Company also purchases options to actively manage its equity portfolio.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS In accordance with U.S. GAAP, fair value is defined as the price 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. There is a three-level valuation hierarchy for disclosure of fair value measurements. The valuation hierarchy is based upon whether the inputs to the valuation of an asset or liability are observable or unobservable in the market at the measurement date, with quoted market prices being the highest level (Level 1) and unobservable inputs being the lowest level (Level 3). A fair value measurement will fall within the level of the hierarchy based on the input that is significant to determining such measurement. The three levels are defined as follows: • Level 1 : Observable inputs to the valuation methodology that are quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2 : Observable inputs to the valuation methodology other than quoted market prices (unadjusted) for identical assets or liabilities in active markets. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical assets in markets that are not active and inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. • Level 3 : Inputs to the valuation methodology that are unobservable for the asset or liability. The following table shows the fair value of the Company’s financial instruments and where in the fair value hierarchy the fair value measurements are included as of the dates indicated below: June 30, 2016 Carrying Amount Total Fair Value Level 1 Level 2 Level 3 Fixed maturity investments: U.S. government and government agencies $ 1,805.5 $ 1,805.5 $ 1,765.2 $ 40.3 $ — Non-U.S. government and government agencies 469.6 469.6 — 469.6 — States, municipalities and political subdivisions 504.6 504.6 — 504.6 — Corporate debt: Financial institutions 1,223.6 1,223.6 — 1,223.6 — Industrials 1,476.8 1,476.8 — 1,476.8 — Utilities 140.4 140.4 — 140.4 — Mortgage-backed: Agency mortgage-backed 757.0 757.0 — 618.8 138.2 Non-agency residential mortgage-backed 24.0 24.0 — 24.0 — Commercial mortgage-backed 604.2 604.2 — 604.2 — Asset-backed 788.5 788.5 — 726.2 62.3 Total fixed maturity investments 7,794.2 7,794.2 1,765.2 5,828.5 200.5 Equity securities 202.3 202.3 202.3 — — Other invested assets (1) 820.0 820.0 — — — Total investments $ 8,816.5 $ 8,816.5 $ 1,967.5 $ 5,828.5 $ 200.5 Derivative assets: Foreign exchange contracts $ 1.5 $ 1.5 $ — $ 1.5 $ — Derivative liabilities: Foreign exchange contracts $ 0.4 $ 0.4 $ — $ 0.4 $ — Senior notes 1,293.7 $ 1,352.0 $ — $ 1,352.0 $ — Other long-term debt 23.1 $ 30.0 $ — $ 30.0 $ — December 31, 2015 Carrying Amount Total Fair Value Level 1 Level 2 Level 3 Fixed maturity investments: U.S. government and government agencies $ 1,434.0 $ 1,434.0 $ 1,396.4 $ 37.6 $ — Non-U.S. government and government agencies 556.8 556.8 — 556.8 — States, municipalities and political subdivisions 413.5 413.5 — 413.5 — Corporate debt: Financial institutions 1,275.4 1,275.4 — 1,275.4 — Industrials 1,308.1 1,308.1 — 1,308.1 — Utilities 118.9 118.9 — 118.9 — Mortgage-backed: Agency mortgage-backed 751.8 751.8 — 645.7 106.1 Non-agency residential mortgage-backed 34.0 34.0 — 34.0 — Commercial mortgage-backed 582.8 582.8 — 582.8 — Asset-backed 726.2 726.2 — 663.2 63.0 Total fixed maturity investments 7,201.5 7,201.5 1,396.4 5,636.0 169.1 Equity securities 403.0 403.0 403.0 — — Other invested assets (1) 840.2 840.2 — — — Total investments $ 8,444.7 $ 8,444.7 $ 1,799.4 $ 5,636.0 $ 169.1 Derivative assets: Foreign exchange contracts $ 0.1 $ 0.1 $ — $ 0.1 $ — Derivative liabilities: Foreign exchange contracts $ 3.0 $ 3.0 $ — $ 3.0 $ — Interest rate swaps $ 0.5 $ 0.5 $ — $ 0.5 $ — Senior notes $ 1,292.9 $ 1,337.9 $ — $ 1,337.9 $ — Other long-term debt $ 23.0 $ 27.7 $ — $ 27.7 $ — _______________________ (1) In accordance with U.S. GAAP, other invested assets, excluding other private securities, are measured at fair value using the net asset value per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy. “Other invested assets” exclude other private securities that the Company did not measure at fair value, but are accounted for using the equity method of accounting. Derivative assets and derivative liabilities relating to foreign exchange contracts and interest rate swaps are classified within “other assets” or “accounts payable and accrued liabilities” on the consolidated balance sheets. The following describes the valuation techniques used by the Company to determine the fair value of financial instruments held as of the balance sheet date. Fair Value of Financial Instruments U.S. government and government agencies: Comprised primarily of bonds issued by the U.S. Treasury, the Federal Home Loan Bank, the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association. The fair values of the Company’s U.S. government securities are based on quoted market prices in active markets and are included in the Level 1 fair value hierarchy. The Company believes the market for U.S. Treasury securities is an actively traded market given the high level of daily trading volume. The fair values of U.S. government agency securities are priced using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of U.S. government agency securities are included in the Level 2 fair value hierarchy. Non-U.S. government and government agencies: Comprised of fixed income obligations of non-U.S. governmental entities. The fair values of these securities are based on prices obtained from international indices and are included in the Level 2 fair value hierarchy. States, municipalities and political subdivisions: Comprised of fixed income obligations of U.S. domiciled state and municipality entities. The fair values of these securities are based on prices obtained from the new issue market, and are included in the Level 2 fair value hierarchy. Corporate debt: Comprised of bonds issued by or loan obligations of corporations that are diversified across a wide range of issuers and industries. The fair values of corporate debt that are short-term are priced using spread above the LIBOR yield curve, and the fair values of corporate debt that are long-term are priced using the spread above the risk-free yield curve. The spreads are sourced from broker-dealers, trade prices and the new issue market. As the significant inputs used to price corporate debt are observable market inputs, the fair values of corporate debt are included in the Level 2 fair value hierarchy. Mortgage-backed: Primarily comprised of residential and commercial mortgages originated by both U.S. government agencies (such as the Federal National Mortgage Association) and non-U.S. government agencies. The fair values of mortgage-backed securities originated by U.S. government agencies and non-U.S. government agencies are based on a pricing model that incorporates prepayment speeds and spreads to determine the appropriate average life of mortgage-backed securities. The spreads are sourced from broker-dealers, trade prices and the new issue market. As the significant inputs used to price the mortgage-backed securities are observable market inputs, the fair values of these securities are included in the Level 2 fair value hierarchy, unless the significant inputs used to price the mortgage-backed securities are broker-dealer quotes and the Company is not able to determine if those quotes are based on observable market inputs, in which case the fair value is included in the Level 3 hierarchy. Asset-backed: Principally comprised of bonds backed by pools of automobile loan receivables, home equity loans, credit card receivables and collateralized loan obligations originated by a variety of financial institutions. The fair values of asset-backed securities are priced using prepayment speed and spread inputs that are sourced from the new issue market or broker-dealer quotes. As the significant inputs used to price the asset-backed securities are observable market inputs, the fair values of these securities are included in the Level 2 fair value hierarchy, unless the significant inputs used to price the asset-backed securities are broker-dealer quotes and the Company is not able to determine if those quotes are based on observable market inputs, in which case the fair value is included in the Level 3 hierarchy. Equity securities: Comprised of U.S. and foreign common and preferred stocks and mutual funds. Equities are generally included in the Level 1 fair value hierarchy as prices are obtained from market exchanges in active markets. Non-U.S. mutual funds where the net asset value (the “NAV”) is not provided on a daily basis are included in the Level 3 fair value hierarchy. Other invested assets: Comprised of funds invested in a range of diversified strategies. In accordance with U.S. GAAP, the fair values of the funds are based on the NAV of the funds as reported by the fund manager. Derivative instruments: The fair value of foreign exchange contracts and interest rate futures and swaps are priced from quoted market prices for similar exchange-traded derivatives and pricing valuation models that utilize independent market data inputs. The fair value of derivatives are included in the Level 2 fair value hierarchy. Senior notes: The fair value of the senior notes is based on reported trades. The fair value of the senior notes is included in the Level 2 fair value hierarchy. Other long-term debt: Comprised of the mortgage and credit facility associated with the purchase of office space in Switzerland. The fair value of the other long-term debt is based on the value of the debt using current interest rates. The fair value of the other long-term debt is included in the Level 2 fair value hierarchy. Non-recurring Fair Value of Financial Instruments The Company measures the fair value of certain assets on a non-recurring basis, generally quarterly, annually, or when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. These assets include investments accounted for using the equity method, goodwill and intangible assets. The Company uses a variety of techniques to measure the fair value of these assets when appropriate, such as discounted expected future cash flows or market multiple models. Investments accounted for using the equity method: When the Company determines that the carrying value of these assets may not be recoverable, the Company records the assets at fair value with the loss recognized in income. In such cases, the Company measures the fair value of these assets using the techniques discussed above. Goodwill and intangible assets: The Company tests goodwill and intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable, but at least annually for goodwill and indefinite-lived intangibles. When the Company determines that goodwill and indefinite-lived intangible assets may be impaired, the Company uses techniques, including discounted expected future cash flows and market multiple models, to measure fair value. Rollforward of Level 3 Financial Instruments The following is a reconciliation of the beginning and ending balance of financial instruments using significant unobservable inputs (Level 3): Three Months Ended June 30, 2016 MBS CMBS Total mortgage-backed Asset-backed Equities Opening balance $ 146.1 $ — $ 146.1 $ 63.6 $ — Realized and unrealized gains included in net income 0.6 — 0.6 1.5 — Purchases — — 16.5 — Sales (8.5 ) — (8.5 ) (10.5 ) — Transfers into Level 3 from Level 2 — — — 0.5 — Transfers out of Level 3 into Level 2 (1) — — — (9.3 ) — Ending balance $ 138.2 $ — $ 138.2 $ 62.3 $ — Three Months Ended June 30, 2015 Opening balance $ 132.7 $ — $ 132.7 $ 92.9 $ 48.8 Realized and unrealized (losses) gains included in net income (2.4 ) — (2.4 ) (0.5 ) 9.0 Purchases 1.6 2.8 4.4 2.2 — Sales (35.3 ) — (35.3 ) (7.2 ) — Transfers into Level 3 from Level 2 — 0.3 0.3 17.4 — Transfers out of Level 3 into Level 2 (1) — — — (20.9 ) — Ending balance $ 96.6 $ 3.1 $ 99.7 $ 83.9 $ 57.8 Six Months Ended June 30, 2016 MBS CMBS Total mortgage-backed Asset-backed Equities Opening balance $ 106.1 $ — $ 106.1 $ 63.0 $ — Realized and unrealized gains (losses) included in net income 2.1 — 2.1 0.6 — Purchases 38.8 — 38.8 16.6 — Sales (10.3 ) — (10.3 ) (9.5 ) — Transfers into Level 3 from Level 2 1.5 — 1.5 7.9 — Transfers out of Level 3 into Level 2 (1) — — — (16.3 ) — Ending balance $ 138.2 $ — $ 138.2 $ 62.3 $ — Six Months Ended June 30, 2015 Opening balance $ 180.1 $ 1.7 $ 181.8 $ 55.4 $ 43.3 Realized and unrealized (losses) gains included in net income (1.1 ) 0.1 (1.0 ) (0.6 ) 14.5 Purchases 2.1 4.6 6.7 23.3 — Sales (84.5 ) (3.6 ) (88.1 ) (9.9 ) — Transfers into Level 3 from Level 2 — 0.3 0.3 43.9 — Transfers out of Level 3 into Level 2 (1) — — — (28.2 ) — Ending balance $ 96.6 $ 3.1 $ 99.7 $ 83.9 $ 57.8 _______________________ (1) Transfers out of Level 3 are primarily attributable to the availability of market observable information. The Company attempts to verify the significant inputs used by broker-dealers in determining the fair value of the securities priced by them. If the Company could not obtain sufficient information to determine if the broker-dealers were using significant observable inputs, then such securities have been transferred to the Level 3 fair value hierarchy. The Company believes the prices obtained from the broker-dealers are the best estimate of fair value of the securities being priced as the broker-dealers are typically involved in the initial pricing of the security, and the Company has compared the price per the broker-dealer to other pricing sources and noted no material differences. The Company recognizes transfers between levels at the end of the reporting period. There were no transfers between Level 1 and Level 2 during the period. The Company’s external investment accounting service provider receives prices from internationally recognized independent pricing services to measure the fair values of its fixed maturity investments. Pricing sources are evaluated and selected in a manner to ensure that the most reliable sources are used. The Company uses a pricing service ranking to consistently select the most appropriate pricing service in instances where it receives multiple quotes on the same security. The Company obtains multiple quotes for the majority of its securities. The independent pricing sources obtain market quotations and actual transaction prices for securities that have quoted prices in active markets. Each pricing service has its own proprietary method for determining the fair value of securities that are not actively traded. In general, these methods involve the use of “matrix pricing” in which the independent pricing service uses observable market inputs, including, but not limited to, reported trades, benchmark yields, broker-dealer quotes, interest rates, prepayment speeds, default rates and such other inputs as are available from market sources to determine a reasonable fair value. All of the Company’s securities classified as Level 3 are valued based on unadjusted broker-dealer quotes. This includes less liquid securities such as lower quality asset-backed securities, commercial mortgage-backed securities and residential mortgage-backed securities. The primary valuation inputs include monthly payment information, the probability of default, loss severity rates and estimated prepayment rates. Significant changes in these inputs in isolation would result in a significantly lower or higher fair value measurement. In general, a change in the assumption of the probability of default is accompanied by a directionally similar change in the assumption used for the loss severity in an event of default and prepayment rates. The Company records the unadjusted price provided and validates this price through a process that includes, but is not limited to, monthly and/or quarterly: (i) comparison of prices between two independent sources, with significant differences requiring additional price sources; (ii) quantitative analysis (e.g., comparing the quarterly return for each managed portfolio to their target benchmark, with significant differences identified and investigated); (iii) evaluation of methodologies used by external parties to calculate fair value, including a review of the inputs used for pricing; (iv) comparing the price to the Company’s knowledge of the current investment market; and (v) back-testing, which includes randomly selecting purchased or sold securities and comparing the executed prices to the fair value estimates from the pricing service. In addition to internal controls, management relies on the effectiveness of the valuation controls in place at the Company’s external investment accounting service provider (supported by a Statement on Standards for Attestation Engagements No. 16 report) in conjunction with regular discussion and analysis of the investment portfolio’s structure and performance.

Reserve For Losses And Loss Exp

Reserve For Losses And Loss Expenses	6 Months Ended
	Jun. 30, 2016
Insurance Loss Reserves [Abstract]
Reserve for Losses and Loss Expenses	RESERVE FOR LOSSES AND LOSS EXPENSES The reserve for losses and loss expenses consists of the following: June 30, December 31, Outstanding loss reserves $ 1,727.3 $ 1,678.5 Reserves for losses incurred but not reported 4,895.9 4,777.7 Reserve for losses and loss expenses $ 6,623.2 $ 6,456.2 The table below is a reconciliation of the beginning and ending liability for unpaid losses and loss expenses. Losses incurred and paid are reflected net of reinsurance recoverables. Three Months Ended Six Months Ended 2016 2015 2016 2015 Gross liability at beginning of period $ 6,575.1 $ 5,905.1 $ 6,456.2 $ 5,881.2 Reinsurance recoverable at beginning of period (1,512.0 ) (1,350.3 ) (1,480.0 ) (1,340.3 ) Net liability at beginning of period 5,063.1 4,554.8 4,976.2 4,540.9 Acquisition of net reserve for losses and loss expenses — 257.0 — 257.0 Net losses incurred related to: Current year 403.3 453.3 801.1 842.2 Prior years (37.9 ) (21.8 ) (63.3 ) (85.5 ) Total incurred 365.4 431.5 737.8 756.7 Net paid losses related to: Current year 34.5 28.0 41.2 34.6 Prior years 280.9 285.8 563.4 578.9 Total paid 315.4 313.8 604.6 613.5 Foreign exchange revaluation (6.6 ) 1.3 (2.9 ) (10.3 ) Net liability at end of period 5,106.5 4,930.8 5,106.5 4,930.8 Reinsurance recoverable at end of period 1,516.7 1,433.1 1,516.7 1,433.1 Gross liability at end of period $ 6,623.2 $ 6,363.9 $ 6,623.2 $ 6,363.9 The “Acquisition of net reserve for losses and loss expenses” during the three and six months ended June 30, 2015 represents the net reserves acquired from the Hong Kong and Singapore branches of RSA of $252.8 million and the net reserves from the Labuan branch of RSA of $4.2 million . For the three months ended June 30, 2016, the Company recorded net favorable prior year reserve development in each of its operating segments. The net favorable prior year reserve development in our North American Insurance segment was due to net favorable prior year reserve development in loss years 2010 and prior in our casualty and professional liability lines of business. The net favorable reserve development in the Global Markets Insurance segment was primarily related to the casualty and property lines of business across multiple loss years . The net favorable prior year reserve development in the Reinsurance segment was primarily related to our property reinsurance line of business in the 2014 and 2015 loss years. For the six months ended June 30, 2016, the Company recorded net favorable prior year reserve development in each of its operating segments primarily due to actual loss emergence being lower than initially expected. The net favorable prior year reserve development in the North American Insurance segment was primarily related to the professional liability line of business. The net favorable reserve development in the Global Markets Insurance segment was primarily related to the other specialty and property lines of business, partially offset by unfavorable reserve development in our professional liability line of business . The net favorable prior year reserve development in the Reinsurance segment was primarily related to our property reinsurance and specialty reinsurance lines of business, partially offset by net unfavorable prior year reserve development in our casualty reinsurance line of business. For the three months ended June 30, 2015, the Company had net unfavorable prior year reserve development in the North American Insurance segment and recorded net favorable prior year reserve development in the Global Markets Insurance and Reinsurance segments . T he net unfavorable prior year reserve development in the North American Insurance segment included unfavorable prior year reserve development related to the professional liability and healthcare lines of business . The net favorable prior year reserve development in the Global Markets Insurance and Reinsurance segments was due to actual loss emergence being lower than initially expected across several lines of business . For the six months ended June 30, 2015, the Company had net favorable prior year reserve development in each of its operating segments . The net unfavorable prior year reserve development in the North American Insurance segment for the 2012 through 2014 loss years was primarily related to our healthcare line of business and was due to adverse development on several claims being above our previous expectations . The net favorable prior year reserve development in our Reinsurance segment was primarily due to benign property loss activity, and therefore reported losses were less than our expectations across several lines of business. Although the Company has experienced favorable reserve development in its insurance and reinsurance lines, there is no assurance that conditions and trends that have affected the development of liabilities in the past will continue. It is not appropriate to extrapolate future redundancies based on prior years’ development. The methodology of estimating loss reserves is periodically reviewed to ensure that the key assumptions used in the actuarial models continue to be appropriate.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Under Swiss law, a resident company is subject to income tax at the federal, cantonal and communal levels that is levied on net income. Income attributable to permanent establishments or real estate located abroad is excluded from the Swiss tax base. Allied World Switzerland is a holding company and, therefore, is exempt from cantonal and communal income tax. As a result, Allied World Switzerland is subject to Swiss income tax only at the federal level. Allied World Switzerland is a resident of the Canton of Zug and, as such, is subject to an annual cantonal and communal capital tax on its taxable equity. Allied World Switzerland has a Swiss operating company resident in the Canton of Zug. The operating company is subject to federal, cantonal and communal income tax and to annual cantonal and communal capital tax. Under current Bermuda law, Allied World Assurance Company Holdings, Ltd (“Allied World Bermuda”) and its Bermuda subsidiaries are not required to pay taxes in Bermuda on either income or capital gains. Allied World Bermuda and Allied World Assurance Company, Ltd have received an assurance from the Bermuda Minister of Finance under the Exempted Undertakings Tax Protection Act 1966 of Bermuda, that in the event of any such taxes being imposed, Allied World Bermuda and Allied World Assurance Company, Ltd will be exempted until March 2035. Certain subsidiaries of Allied World Switzerland file U.S. federal income tax returns and various U.S. state income tax returns, as well as income tax returns in Canada, Hong Kong, Ireland, Singapore, and the United Kingdom. The U.S. Internal Revenue Service (the “IRS”) is currently conducting an audit of the the 2014 tax return of the U.S. services company. As the audit has just started, it is too early to determine if there will be any findings from the audit. During the quarter ended June 30, 2016, the IRS completed its audit of the 2012 consolidated tax return of the Company's U.S. subsidiaries. There were no findings as a result of the audit. To the best of the Company’s knowledge, there are no other examinations pending by any other tax authority. Management has deemed all material tax positions to have a greater than 50% likelihood of being sustained based on technical merits if challenged. The Company does not expect any material unrecognized tax benefits within 12 months of June 30, 2016 .

Shareholders' Equity

Shareholders' Equity	6 Months Ended
	Jun. 30, 2016
Stockholders' Equity Note [Abstract]
Shareholders' Equity	SHAREHOLDERS’ EQUITY a) Authorized shares The issued share capital consists of the following: June 30, December 31, Common shares issued and fully paid, 2016 and 2015: CHF 4.10 per share 93,586,418 95,523,230 Share capital at end of period $ 366.7 $ 386.7 Six Months Ended June 30, 2016 Shares issued at beginning of period 95,523,230 Shares canceled (1,936,812 ) Total shares issued at end of period 93,586,418 Treasury shares issued at beginning of period 4,563,595 Shares repurchased 3,952,243 Shares issued out of treasury (456,558 ) Shares canceled (1,936,812 ) Total treasury shares at end of period 6,122,468 Total shares outstanding at end of period 87,463,950 During the six months ended June 30, 2016 , 1,936,812 shares repurchased and designated for cancellation were constructively retired and canceled. b) Dividends The Company paid the following dividends during the six months ended June 30, 2016 : Dividend Paid Dividend Per Share Total Amount Paid June 30, 2016 $ 0.260 $ 22.8 March 31, 2016 $ 0.260 $ 23.4 On April 19, 2016, the shareholders approved the Company's proposal to pay cash dividends in the form of a distribution out of general legal reserve from capital contributions. The distribution amount will be paid to shareholders in quarterly installments of $0.26 per share. The first installment was distributed on June 30, 2016. The Company expects to distribute the remaining installments of the dividend in September 2016, December 2016 and March 2017. c) Share Repurchases On April 19, 2016, the shareholders approved a share repurchase program (the “2016 share repurchase program”) in order for the Company to repurchase up to $500 million of its common shares. The 2016 share repurchase program supersedes the 2014 share repurchase program and no further repurchases will be made under the 2014 share repurchase program. Repurchases may be effected from time to time through open market purchases, privately negotiated transactions, tender offers or otherwise. The timing, form and amount of the share repurchases under the 2016 share repurchase program will depend on a variety of factors, including market conditions, the Company’s capital position, legal requirements and other factors. Under the terms of the 2016 share repurchase program, the first three million of common shares repurchased will remain in treasury and will be used by the Company to satisfy share delivery obligations under its equity-based compensation plans. Any additional common shares repurchased will be designated for cancellation at acquisition and will be canceled upon shareholder approval. Shares repurchased and designated for cancellation are constructively retired and recorded as a share cancellation. The Company’s share repurchases were as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Common shares repurchased 2,491,355 4,776,224 3,952,243 6,047,437 Total cost of shares repurchased $ 90.0 $ 194.4 $ 140.0 $ 245.3 Average price per share $ 36.12 $ 40.69 $ 35.42 $ 40.56 On May 6, 2015, the Company repurchased 4,053,537 shares from Exor S.A. at a repurchase price of $40.546 per share, for an aggregate purchase price of $164.4 million . The repurchase was executed under the 2014 share repurchase program.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The following table sets forth the comparison of basic and diluted earnings per share: Three Months Ended Six Months Ended 2016 2015 2016 2015 Basic earnings per share: Net income $ 153.4 $ 9.5 $ 227.5 $ 133.8 Weighted average common shares outstanding 88,742,484 92,441,730 89,495,564 94,178,989 Basic earnings per share $ 1.73 $ 0.10 $ 2.54 $ 1.42 Three Months Ended Six Months Ended 2016 2015 2016 2015 Diluted earnings per share: Net income $ 153.4 $ 9.5 $ 227.5 $ 133.8 Weighted average common shares outstanding 88,742,484 92,441,730 89,495,564 94,178,989 Share equivalents: Stock options 829,584 1,075,735 832,432 1,102,252 RSUs and performance-based equity awards 443,336 452,938 479,038 534,653 Employee share purchase plan 25,105 13,823 23,780 14,561 Weighted average common shares and common share equivalents outstanding - diluted 90,040,509 93,984,226 90,830,814 95,830,455 Diluted earnings per share $ 1.70 $ 0.10 $ 2.50 $ 1.40 For the three and six months ended June 30, 2016 , there were 229,999 and 235,085 , respectively, common share equivalents considered anti-dilutive and therefore excluded from the calculation of diluted earnings per share. There were no anti-dilutive shares for the three and six months ended June 30, 2015 .

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION The determination of reportable segments is based on how senior management monitors the Company’s underwriting operations. Management monitors the performance of its direct underwriting operations based on the geographic location of the Company’s offices, the markets and customers served and the type of accounts written. The Company is currently organized into three operating segments: North American Insurance, Global Markets Insurance and Reinsurance. All lines of business fall within these classifications. The North American Insurance segment includes the Company’s specialty insurance operations in the United States, Bermuda and Canada, as well as the Company's claims administration services operation. This segment provides both property and specialty casualty insurance to North American domiciled accounts. The Global Markets Insurance segment includes the Company’s insurance operations in Europe and Asia Pacific, which includes offices in Dublin, Hong Kong, Labuan, London, Singapore, Sydney and Zug. This segment provides both property and casualty insurance primarily to non-North American domiciled accounts. The Reinsurance segment includes the Company’s reinsurance operations in Bermuda, Labuan, London, Singapore, the United States and Zug. This segment provides reinsurance of property, general casualty, professional liability, specialty lines and property catastrophe coverages written by insurance companies. The Company presently writes reinsurance on both a treaty and a facultative basis, targeting several niche reinsurance markets. Responsibility and accountability for the results of underwriting operations are assigned by major line of business within each segment. Because the Company does not manage its assets by segment, investment income, interest expense and total assets are not allocated to individual reportable segments. General and administrative expenses are allocated to segments based on various factors, including expenses directly attributable to individual segments, staff count and each segment’s proportional share of gross premiums written. The Company measures its segment profit or loss as underwriting income or loss plus other insurance-related income and expenses, which may include the net earnings from our claims administration services operations and other income or expense that is not directly related to our underwriting operations. Management measures results for each segment's underwriting income or loss on the basis of the “loss and loss expense ratio,” “acquisition cost ratio,” “general and administrative expense ratio,” “expense ratio” and the “combined ratio.” The “loss and loss expense ratio” is derived by dividing net losses and loss expenses by net premiums earned. The “acquisition cost ratio” is derived by dividing acquisition costs by net premiums earned. The “general and administrative expense ratio” is derived by dividing general and administrative expenses by net premiums earned. The expense ratio is the sum of the “acquisition cost ratio” and the “general and administrative expense ratio”. The “combined ratio” is the sum of the “loss and loss expense ratio,” the “acquisition cost ratio” and the “general and administrative expense ratio.” The following tables provide a summary of the segment results: Three Months Ended June 30, 2016 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 508.4 $ 125.4 $ 166.5 $ 800.3 Net premiums written 330.8 88.2 159.1 578.1 Net premiums earned 329.6 94.1 179.2 602.9 Net losses and loss expenses (209.9 ) (61.1 ) (94.4 ) (365.4 ) Acquisition costs (37.4 ) (16.3 ) (33.7 ) (87.4 ) General and administrative expenses (56.8 ) (31.5 ) (16.4 ) (104.7 ) Underwriting income (loss) 25.5 (14.8 ) 34.7 45.4 Other insurance-related income 0.9 — 4.3 5.2 Other insurance-related expenses (0.6 ) — (1.1 ) (1.7 ) Segment income (loss) 25.8 (14.8 ) 37.9 48.9 Net investment income 55.8 Net realized investment gains 74.5 Amortization of intangible assets (2.5 ) Interest expense (19.9 ) Foreign exchange gain 2.9 Income before income taxes $ 159.7 Loss and loss expense ratio 63.7 % 64.9 % 52.7 % 60.6 % Acquisition cost ratio 11.4 % 17.3 % 18.8 % 14.5 % General and administrative expense ratio 17.2 % 33.5 % 9.1 % 17.4 % Expense ratio 28.6 % 50.8 % 27.9 % 31.9 % Combined ratio 92.3 % 115.7 % 80.6 % 92.5 % Three Months Ended June 30, 2015 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 517.5 $ 135.0 $ 173.5 $ 826.0 Net premiums written 372.2 69.3 162.2 603.7 Net premiums earned 328.6 102.6 215.2 646.4 Net losses and loss expenses (237.7 ) (65.8 ) (128.0 ) (431.5 ) Acquisition costs (34.2 ) (24.3 ) (42.1 ) (100.6 ) General and administrative expenses (58.2 ) (30.7 ) (19.5 ) (108.4 ) Underwriting (loss) income (1.5 ) (18.2 ) 25.6 5.9 Other insurance-related income 0.9 — — 0.9 Other insurance-related expenses (0.6 ) (0.6 ) — (1.2 ) Segment (loss) income (1.2 ) (18.8 ) 25.6 5.6 Net investment income 42.8 Net realized investment losses (20.2 ) Amortization of intangible assets (2.8 ) Interest expense (14.5 ) Foreign exchange loss (1.3 ) Income before income taxes $ 9.6 Loss and loss expense ratio 72.4 % 64.1 % 59.5 % 66.8 % Acquisition cost ratio 10.4 % 23.7 % 19.6 % 15.6 % General and administrative expense ratio 17.7 % 29.9 % 9.1 % 16.8 % Expense ratio 28.1 % 53.6 % 28.7 % 32.4 % Combined ratio 100.5 % 117.7 % 88.2 % 99.2 % Six Months Ended June 30, 2016 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 887.5 $ 241.0 $ 535.3 $ 1,663.8 Net premiums written 597.0 175.8 509.3 1,282.1 Net premiums earned 645.9 188.3 348.8 1,183.0 Net losses and loss expenses (426.2 ) (128.9 ) (182.7 ) (737.8 ) Acquisition costs (71.3 ) (34.2 ) (70.2 ) (175.7 ) General and administrative expenses (109.0 ) (60.6 ) (31.5 ) (201.1 ) Underwriting (loss) income 39.4 (35.4 ) 64.4 68.4 Other insurance-related income 1.5 — 4.2 5.7 Other insurance-related expenses (1.3 ) — (1.5 ) (2.8 ) Segment income 39.6 (35.4 ) 67.1 71.3 Net investment income 109.1 Net realized investment gains 93.4 Amortization of intangible assets (5.0 ) Interest expense (39.8 ) Foreign exchange gain 5.9 Income before income taxes $ 234.9 Loss and loss expense ratio 66.0 % 68.4 % 52.4 % 62.4 % Acquisition cost ratio 11.0 % 18.1 % 20.1 % 14.9 % General and administrative expense ratio 16.9 % 32.1 % 9.0 % 17.0 % Expense ratio 27.9 % 50.2 % 29.1 % 31.9 % Combined ratio 93.9 % 118.6 % 81.5 % 94.3 % Six Months Ended June 30, 2015 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 898.2 $ 195.6 $ 612.8 $ 1,706.6 Net premiums written 669.1 112.2 594.9 1,376.2 Net premiums earned 641.5 152.7 420.7 1,214.9 Net losses and loss expenses (433.2 ) (86.3 ) (237.2 ) (756.7 ) Acquisition costs (65.3 ) (31.3 ) (82.7 ) (179.3 ) General and administrative expenses (117.5 ) (48.7 ) (39.3 ) (205.5 ) Underwriting income (loss) 25.5 (13.6 ) 61.5 73.4 Other insurance-related income 1.9 — — 1.9 Other insurance-related expenses (1.5 ) (1.6 ) — (3.1 ) Segment income (loss) 25.9 (15.2 ) 61.5 72.2 Net investment income 87.3 Net realized investment gains 24.8 Amortization of intangible assets (3.4 ) Interest expense (28.8 ) Foreign exchange loss (11.2 ) Income before income taxes $ 140.9 Loss and loss expense ratio 67.5 % 56.5 % 56.4 % 62.3 % Acquisition cost ratio 10.2 % 20.5 % 19.7 % 14.8 % General and administrative expense ratio 18.3 % 31.9 % 9.3 % 16.9 % Expense ratio 28.5 % 52.4 % 29.0 % 31.7 % Combined ratio 96.0 % 108.9 % 85.4 % 94.0 % The following table shows an analysis of the Company’s gross premiums written by geographic location of the Company’s subsidiaries and branches. All intercompany premiums have been eliminated. Three Months Ended Six Months Ended 2016 2015 2016 2015 United States $ 495.6 $ 483.1 $ 1,020.0 $ 1,019.8 Bermuda 140.9 167.9 285.0 364.5 Asia Pacific 91.4 93.2 193.6 133.3 Europe 65.1 76.3 153.7 180.2 Canada 7.3 5.5 11.5 8.8 Total gross premiums written $ 800.3 $ 826.0 $ 1,663.8 $ 1,706.6 Europe includes gross premiums written attributable to Switzerland of $2.5 million and $4.3 million for the three months ended June 30, 2016 and 2015 , respectively, and $38.1 million and $44.7 million for the six months ended June 30, 2016 and 2015 , respectively. The following table shows the Company's net premiums earned by line of business for each segment for each of the periods indicated. Three Months Ended Six Months Ended 2016 2015 2016 2015 North American Insurance: Professional liability $ 103.1 $ 94.7 $ 204.6 $ 183.5 Casualty 104.3 109.2 201.1 214.1 Programs 43.3 36.7 82.9 70.9 Property 34.6 42.5 68.3 83.9 Other specialty 28.1 17.3 53.3 32.9 Healthcare 16.2 28.2 35.7 56.2 Total 329.6 328.6 645.9 641.5 Global Markets Insurance: Other specialty 30.2 27.2 61.0 39.9 Casualty 22.2 31.0 45.8 37.0 Professional liability 25.5 26.1 49.0 49.3 Property 16.2 18.3 32.5 26.5 Total 94.1 102.6 188.3 152.7 Reinsurance: Property 83.4 104.8 167.8 209.1 Casualty 46.7 58.9 92.8 115.8 Specialty 49.1 51.5 88.2 95.8 Total 179.2 215.2 348.8 420.7 Total net premiums earned $ 602.9 $ 646.4 $ 1,183.0 $ 1,214.9

Commitments And Contingencies

Commitments And Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES The Company, in common with the insurance industry in general, is subject to litigation and arbitration in the normal course of its business. These legal proceedings generally relate to claims asserted by or against the Company in the ordinary course of insurance or reinsurance operations. Estimated amounts payable under these proceedings are included in the reserve for losses and loss expenses in the Company’s consolidated balance sheets. As of June 30, 2016 , the Company was not a party to any material legal proceedings arising outside the ordinary course of business that management believes will have a material adverse effect on the Company’s results of operations, financial position or cash flow.

Condensed Consolidated Guaranto

Condensed Consolidated Guarantor Financial Statements	6 Months Ended
	Jun. 30, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidated Guarantor Financial Statements	CONDENSED CONSOLIDATED GUARANTOR FINANCIAL STATEMENTS The following tables present unaudited condensed consolidating financial information as of June 30, 2016 and December 31, 2015 and for the three and six months ended June 30, 2016 and 2015 for Allied World Switzerland (the “Parent Guarantor”) and Allied World Bermuda (the “Subsidiary Issuer”). The Subsidiary Issuer is a direct, 100% -owned subsidiary of the Parent Guarantor. Investments in subsidiaries are accounted for by the Parent Guarantor under the equity method for purposes of the supplemental consolidating presentation. Earnings of subsidiaries are reflected in the Parent Guarantor’s investment accounts and earnings. The Parent Guarantor fully and unconditionally guarantees the senior notes issued by the Subsidiary Issuer. Unaudited Condensed Consolidating Balance Sheet: As of June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated ASSETS: Investments $ — $ — $ 8,936.3 $ — $ 8,936.3 Cash and cash equivalents 22.6 1.1 560.8 — 584.5 Insurance balances receivable — — 961.0 — 961.0 Funds held — — 279.1 — 279.1 Reinsurance recoverable — — 1,516.7 — 1,516.7 Reinsurance recoverable on paid losses — — 73.8 — 73.8 Net deferred acquisition costs — — 168.9 — 168.9 Goodwill and intangible assets — — 506.1 — 506.1 Balances receivable on sale of investments — — 114.6 — 114.6 Investments in subsidiaries 3,381.1 4,190.9 — (7,572.0 ) — Due from subsidiaries 186.3 275.6 11.3 (473.2 ) — Other assets 1.5 0.8 724.0 — 726.3 Total assets $ 3,591.5 $ 4,468.4 $ 13,852.6 $ (8,045.2 ) $ 13,867.3 LIABILITIES: Reserve for losses and loss expenses $ — $ — $ 6,623.2 $ — $ 6,623.2 Unearned premiums — — 1,822.1 — 1,822.1 Reinsurance balances payable — — 227.7 — 227.7 Balances due on purchases of investments — — 155.0 — 155.0 Senior notes — 1,293.7 — — 1,293.7 Other long-term debt — — 23.1 — 23.1 Due to subsidiaries 3.6 7.7 461.9 (473.2 ) — Other liabilities 3.4 21.4 113.2 — 138.0 Total liabilities 7.0 1,322.8 9,426.2 (473.2 ) 10,282.8 Total shareholders’ equity 3,584.5 3,145.6 4,426.4 (7,572.0 ) 3,584.5 Total liabilities and shareholders’ equity $ 3,591.5 $ 4,468.4 $ 13,852.6 $ (8,045.2 ) $ 13,867.3 As of December 31, 2015 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated ASSETS: Investments — — 8,571.2 — $ 8,571.2 Cash and cash equivalents 21.8 1.0 585.2 — 608.0 Insurance balances receivable — — 745.9 — 745.9 Funds held — — 640.8 — 640.8 Reinsurance recoverable — — 1,480.0 — 1,480.0 Reinsurance recoverable on paid losses — — 96.4 96.4 Net deferred acquisition costs — — 165.2 — 165.2 Goodwill and intangible assets — — 504.7 — 504.7 Balances receivable on sale of investments — — 36.9 — 36.9 Investments in subsidiaries 3,347.0 4,396.3 — (7,743.3 ) — Due from subsidiaries 173.1 36.4 16.8 (226.3 ) — Other assets 1.8 0.1 660.9 — 662.8 Total assets $ 3,543.7 $ 4,433.8 $ 13,504.0 $ (7,969.6 ) $ 13,511.9 LIABILITIES: Reserve for losses and loss expenses — — 6,456.2 — $ 6,456.2 Unearned premiums — — 1,683.3 — 1,683.3 Reinsurance balances payable — — 214.4 — 214.4 Balances due on purchases of investments — — 125.1 — 125.1 Senior notes — 1,292.9 — — 1,292.9 Other long-term debt — — 23.0 — 23.0 Due to subsidiaries 8.6 8.3 209.5 (226.4 ) — Other liabilities 2.6 22.2 159.7 — 184.5 Total liabilities 11.2 1,323.4 8,871.2 (226.4 ) 9,979.4 Total shareholders’ equity 3,532.5 3,110.4 4,632.8 (7,743.2 ) 3,532.5 Total liabilities and shareholders’ equity $ 3,543.7 $ 4,433.8 $ 13,504.0 $ (7,969.6 ) $ 13,511.9 Unaudited Condensed Consolidating Statement of Operations and Comprehensive Income: Three Months Ended June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated Net premiums earned $ — $ — $ 602.9 $ — $ 602.9 Net investment income — — 55.8 — 55.8 Net realized investment gains (losses) — — 74.5 — 74.5 Other income — — 5.2 — 5.2 Net losses and loss expenses — — (365.4 ) — (365.4 ) Acquisition costs — — (87.4 ) — (87.4 ) General and administrative expenses 2.0 (0.1 ) (106.6 ) — (104.7 ) Other expense — — (1.7 ) — (1.7 ) Amortization of intangible assets — — (2.5 ) — (2.5 ) Interest expense — (19.4 ) (0.5 ) — (19.9 ) Foreign exchange gain (loss) (0.1 ) — 3.0 — 2.9 Income tax (expense) benefit (1.0 ) — (5.3 ) — (6.3 ) Equity in earnings of consolidated subsidiaries 152.5 170.6 — (323.1 ) — NET INCOME (LOSS) $ 153.4 $ 151.1 $ 172.0 $ (323.1 ) $ 153.4 Other comprehensive loss 0.1 — 0.1 (0.1 ) 0.1 COMPREHENSIVE INCOME (LOSS) $ 153.5 $ 151.1 $ 172.1 $ (323.2 ) $ 153.5 Three Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated Net premiums earned $ — $ — $ 646.4 $ — $ 646.4 Net investment income — — 42.8 — 42.8 Net realized investment gains (losses) — — (20.2 ) — (20.2 ) Other income — — 0.9 — 0.9 Net losses and loss expenses — — (431.5 ) — (431.5 ) Acquisition costs — — (100.6 ) — (100.6 ) General and administrative expenses (10.2 ) (0.4 ) (97.8 ) — (108.4 ) Other expense — — (1.2 ) — (1.2 ) Amortization of intangible assets — — (2.8 ) — (2.8 ) Interest expense — (13.9 ) (0.6 ) — (14.5 ) Foreign exchange gain (loss) — — (1.3 ) — (1.3 ) Income tax (expense) benefit 0.6 — (0.7 ) — (0.1 ) Equity in earnings of consolidated subsidiaries 19.1 31.9 — (51.0 ) — NET INCOME (LOSS) $ 9.5 $ 17.6 $ 33.4 $ (51.0 ) $ 9.5 Other comprehensive loss (3.3 ) — (3.3 ) 3.3 (3.3 ) COMPREHENSIVE INCOME (LOSS) $ 6.2 $ 17.6 $ 30.1 $ (47.7 ) $ 6.2 Six Months Ended June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated Net premiums earned $ — $ — $ 1,183.0 $ — $ 1,183.0 Net investment income — — 109.1 — 109.1 Net realized investment gains (losses) — — 93.4 — 93.4 Other income — — 5.7 — 5.7 Net losses and loss expenses — — (737.8 ) — (737.8 ) Acquisition costs — — (175.7 ) — (175.7 ) General and administrative expenses 2.6 0.4 (204.1 ) — (201.1 ) Other expense — — (2.8 ) — (2.8 ) Amortization of intangible assets — — (5.0 ) — (5.0 ) Interest expense — (38.8 ) (1.0 ) — (39.8 ) Foreign exchange gain (loss) (0.1 ) — 6.0 — 5.9 Income tax (expense) benefit (1.3 ) — (6.1 ) — (7.4 ) Equity in earnings of consolidated subsidiaries 226.3 266.5 — (492.8 ) — NET INCOME (LOSS) $ 227.5 $ 228.1 $ 264.7 $ (492.8 ) $ 227.5 Other comprehensive loss 3.3 — 3.3 (3.3 ) 3.3 COMPREHENSIVE INCOME (LOSS) $ 230.8 $ 228.1 $ 268.0 $ (496.1 ) $ 230.8 Six Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated Net premiums earned $ — $ — $ 1,214.9 $ — $ 1,214.9 Net investment income — — 87.3 — 87.3 Net realized investment gains (losses) — — 24.8 — 24.8 Other income — — 1.9 — 1.9 Net losses and loss expenses — — (756.7 ) — (756.7 ) Acquisition costs — — (179.3 ) — (179.3 ) General and administrative expenses (19.6 ) (0.2 ) (185.7 ) — (205.5 ) Other expense — — (3.1 ) — (3.1 ) Amortization of intangible assets — — (3.4 ) — (3.4 ) Interest expense — (27.7 ) (1.1 ) — (28.8 ) Foreign exchange gain (loss) — — (11.2 ) — (11.2 ) Income tax (expense) benefit (0.1 ) — (7.0 ) — (7.1 ) Equity in earnings of consolidated subsidiaries 153.5 175.6 — (329.1 ) — NET INCOME (LOSS) $ 133.8 $ 147.7 $ 181.4 $ (329.1 ) $ 133.8 Other comprehensive loss (3.3 ) — (3.3 ) 3.3 (3.3 ) COMPREHENSIVE INCOME (LOSS) $ 130.5 $ 147.7 $ 178.1 $ (325.8 ) $ 130.5 Unaudited Condensed Consolidating Statement of Cash Flows: Six Months Ended June 30, 2016 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES $ 183.4 $ 194.7 $ 552.5 $ (429.1 ) $ 501.5 CASH FLOWS PROVIDED BY (USED IN) INVESTING ACTIVITIES: Purchases of trading securities — — (3,257.8 ) — (3,257.8 ) Purchases of other invested assets — — (33.2 ) — (33.2 ) Sales of trading securities — — 2,932.2 — 2,932.2 Sales of other invested assets — — 37.3 — 37.3 Net cash paid for acquisitions — — (1.2 ) — (1.2 ) Other — — (19.5 ) — (19.5 ) Net cash provided by (used in) investing activities — — (342.2 ) — (342.2 ) CASH FLOWS PROVIDED BY (USED IN) FINANCING ACTIVITIES: Dividends paid (46.2 ) — — — (46.2 ) Intercompany dividend paid — (194.6 ) (234.5 ) 429.1 — Proceeds from the exercise of stock options 3.1 — — — 3.1 Share repurchases (139.5 ) — — — (139.5 ) Repayment of other long-term debt — — (0.2 ) — (0.2 ) Net cash provided by (used in) financing activities (182.6 ) (194.6 ) (234.7 ) 429.1 (182.8 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 0.8 0.1 (24.4 ) — (23.5 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 21.8 1.0 585.2 — 608.0 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 22.6 $ 1.1 $ 560.8 $ — $ 584.5 Six Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES: $ 278.8 $ 298.6 $ 471.9 $ (624.1 ) $ 425.2 CASH FLOWS PROVIDED BY (USED IN) INVESTING ACTIVITIES: Purchases of trading securities — — (2,854.8 ) — (2,854.8 ) Purchases of other invested assets — — (73.1 ) — (73.1 ) Sales of trading securities — — 2,953.6 — 2,953.6 Sales of other invested assets — — 85.5 — 85.5 Net cash paid for acquisitions — — (141.5 ) — (141.5 ) Other — — (44.1 ) — (44.1 ) Net cash provided by (used in) investing activities — — (74.4 ) — (74.4 ) CASH FLOWS PROVIDED BY (USED IN) FINANCING ACTIVITIES: Dividends paid (43.2 ) — — — (43.2 ) Intercompany dividends paid — (298.4 ) (325.7 ) 624.1 — Proceeds from the exercise of stock options 7.4 — — — 7.4 Proceeds from other long-term debt — — 3.9 — 3.9 Share repurchases (246.4 ) — — — (246.4 ) Net cash provided by (used in) financing activities (282.2 ) (298.4 ) (321.8 ) 624.1 (278.3 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS (3.4 ) 0.2 75.7 — 72.5 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 32.6 1.7 555.0 — 589.3 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 29.2 $ 1.9 $ 630.7 $ — $ 661.8 Notes to Parent Company Condensed Financial Information a) Dividends Allied World Switzerland received cash dividends from its subsidiaries of $194.6 million and $298.4 million for the six months ended June 30, 2016 and 2015 , respectively. Such dividends are included in “cash flows provided by (used in) operating activities” in the unaudited condensed consolidating cash flows.

Basis of Preparation and Cons20

Basis of Preparation and Consolidation (Policies)	6 Months Ended
	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of accounting	Intercompany accounts and transactions have been eliminated on consolidation and all entities meeting consolidation requirements have been included in the unaudited condensed consolidated financial statements. To facilitate comparison of information across periods, certain reclassifications have been made to prior year amounts to conform to the current year's presentation. These unaudited condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with Article 10 of Regulation S-X as promulgated by the U.S. Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, these unaudited condensed consolidated financial statements reflect all adjustments that are normal and recurring in nature and necessary for a fair presentation of financial position and results of operations as of the end of and for the periods presented. The results of operations for any interim period are not necessarily indicative of the results for a full year.
Use of estimates	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts 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. Actual results could differ from those estimates. The significant estimates reflected in the Company’s financial statements, include, but are not limited to: • The premium estimates for certain reinsurance agreements, • Recoverability of deferred acquisition costs, • The reserve for outstanding losses and loss expenses, • Valuation of ceded reinsurance recoverables, • Determination of impairment of goodwill and other intangible assets, and • Valuation of financial instruments.

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2016
Investments [Abstract]
Schedule of trading securities	Securities accounted for at fair value with changes in fair value recognized in the unaudited condensed consolidated statements of operations and comprehensive income (the “consolidated income statements”) by category are as follows: June 30, 2016 December 31, 2015 Fair Value Amortized Cost Fair Value Amortized Cost U.S. government and government agencies $ 1,805.5 $ 1,792.2 $ 1,434.0 $ 1,437.9 Non-U.S. government and government agencies 469.6 479.8 556.8 579.2 States, municipalities and political subdivisions 504.6 476.4 413.5 396.0 Corporate debt: Financial institutions 1,223.6 1,205.8 1,275.4 1,277.3 Industrials 1,476.8 1,461.5 1,308.1 1,345.6 Utilities 140.4 140.3 118.9 125.4 Mortgage-backed Agency mortgage-backed 757.0 742.1 751.8 745.4 Non-agency residential mortgage-backed 24.0 23.1 34.0 32.4 Commercial mortgage-backed 604.2 637.0 582.8 600.1 Asset-backed 788.5 810.8 726.2 751.1 Total fixed maturity investments $ 7,794.2 $ 7,769.0 $ 7,201.5 $ 7,290.6 June 30, 2016 December 31, 2015 Fair Value Original Cost Fair Value Original Cost Equity securities $ 202.3 $ 205.3 $ 403.0 $ 395.3 Other invested assets 820.0 767.0 840.2 770.9 $ 1,022.3 $ 972.3 $ 1,243.2 $ 1,166.2
Schedule of other invested assets	Details regarding the carrying value, redemption characteristics and unfunded investment commitments of the other invested assets portfolio as of June 30, 2016 and December 31, 2015 were as follows: Investment Type Carrying Value as of June 30, 2016 Investments Estimated Investments Redemption (1) Redemption (1) Unfunded Private equity (primary and secondary) $ 248.8 $ 248.8 1 - 7 Years $ — $ 245.7 Levered credit 218.4 218.4 4 - 8 Years — 200.6 Real estate 25.3 25.3 7 - 9 Years — 189.3 Distressed 5.1 5.1 2 Years — 3.8 Total private equity 497.6 497.6 — 639.4 Distressed 168.5 0.1 2 Years 168.4 Monthly 90 Days — Relative value credit 81.8 — 81.8 Quarterly 60 Days — Equity long/short 62.2 — 62.2 Quarterly 45 Days — Fund of funds 9.9 — 9.9 Annual 60 Days — Total hedge funds 322.4 0.1 322.3 — Total other invested assets at fair value 820.0 497.7 322.3 639.4 Other private securities 119.8 — 119.8 — Total other invested assets $ 939.8 $ 497.7 $ 442.1 $ 639.4 Investment Type Carrying Value as of December 31, 2015 Investments Estimated Investments Redemption (1) Redemption (1) Unfunded Private equity (primary and secondary) $ 236.4 $ 236.4 1 - 7 Years $ — $ 231.0 Levered credit 205.9 205.9 4 - 8 Years — 179.0 Distressed 5.1 5.1 2 Years — 3.8 Real estate — — 7 - 9 Years — 200.0 Total private equity 447.4 447.4 — 613.8 Distressed 215.6 54.6 2 Years 161.0 Monthly 90 Days — Equity long/short 58.0 — 58.0 Quarterly 45 Days — Relative value credit 105.4 — 105.4 Quarterly 60 Days — Total hedge funds 379.0 54.6 324.4 — High yield loan fund 13.8 — 13.8 Monthly 30 days — Total other invested assets at fair value 840.2 502.0 338.2 613.8 Other private securities 126.5 — 126.5 — Total other invested assets $ 966.7 $ 502.0 $ 464.7 $ 613.8 _______________________ (1) The redemption frequency and notice periods only apply to the investments without redemption restrictions. Some or all of these investments may be subject to a gate as described below.
Schedule of net investment income	Three Months Ended Six Months Ended 2016 2015 2016 2015 Fixed maturity investments $ 48.9 $ 41.2 $ 96.9 $ 77.4 Equity securities 1.4 4.9 3.3 8.4 Other invested assets: hedge funds and private equity 7.6 4.6 12.3 13.0 Other invested assets: other private securities 1.7 (3.8 ) 4.7 (2.9 ) Cash and cash equivalents 0.8 0.4 1.3 0.9 Expenses (4.6 ) (4.5 ) (9.4 ) (9.5 ) Net investment income $ 55.8 $ 42.8 $ 109.1 $ 87.3
Components of realized gains and losses	Three Months Ended Six Months Ended 2016 2015 2016 2015 Gross realized gains on sale of invested assets $ 46.1 $ 36.1 $ 100.2 $ 81.4 Gross realized losses on sale of invested assets (26.9 ) (10.1 ) (68.7 ) (23.1 ) Net realized and unrealized gains (losses) on derivatives 0.1 13.9 (22.9 ) 2.3 Mark-to-market gains (losses): Fixed maturity investments, trading 55.4 (52.7 ) 117.7 (27.2 ) Equity securities, trading 0.9 (0.3 ) (14.2 ) 5.1 Other invested assets, trading (1.1 ) (7.1 ) (18.7 ) (13.7 ) Net realized investment gains (losses) $ 74.5 $ (20.2 ) $ 93.4 $ 24.8

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Unrealized and realized gains (losses) on derivatives recorded in the unaudited condensed consolidated income statements	The following table provides the net realized and unrealized gains (losses) on derivatives not designated as hedges recorded on the consolidated income statements: Three Months Ended Six Months Ended 2016 2015 2016 2015 Foreign exchange contracts $ 3.3 $ 1.2 $ 1.1 $ (6.2 ) Total included in foreign exchange (gain) loss 3.3 1.2 1.1 (6.2 ) Foreign exchange contracts (0.4 ) (0.3 ) (15.3 ) 0.8 Interest rate swaps 0.5 14.2 (7.6 ) 1.5 Total included in net realized investment gains (losses) 0.1 13.9 (22.9 ) 2.3 Total realized and unrealized gains (losses) on derivatives $ 3.4 $ 15.1 $ (21.8 ) $ (3.9 )
Location and amounts of derivative fair values on the unaudited condensed consolidated balance sheets	The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheets: June 30, 2016 December 31, 2015 Asset Derivative Notional Amount Asset Derivative Fair Value Liability Derivative Notional Amount Liability Derivative Fair Value Asset Derivative Notional Amount Asset Derivative Fair Value Liability Derivative Notional Amount Liability Derivative Fair Value Foreign exchange contracts $ 83.4 $ 1.5 $ 48.6 $ 0.4 $ 41.1 $ 0.1 $ 244.8 $ 3.0 Interest rate swaps — — — — — — 328.2 0.5 Total derivatives $ 83.4 $ 1.5 $ 48.6 $ 0.4 $ 41.1 $ 0.1 $ 573.0 $ 3.5

Fair Value Of Financial Instr23

Fair Value Of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair value hierarchy and related disclosures	The following table shows the fair value of the Company’s financial instruments and where in the fair value hierarchy the fair value measurements are included as of the dates indicated below: June 30, 2016 Carrying Amount Total Fair Value Level 1 Level 2 Level 3 Fixed maturity investments: U.S. government and government agencies $ 1,805.5 $ 1,805.5 $ 1,765.2 $ 40.3 $ — Non-U.S. government and government agencies 469.6 469.6 — 469.6 — States, municipalities and political subdivisions 504.6 504.6 — 504.6 — Corporate debt: Financial institutions 1,223.6 1,223.6 — 1,223.6 — Industrials 1,476.8 1,476.8 — 1,476.8 — Utilities 140.4 140.4 — 140.4 — Mortgage-backed: Agency mortgage-backed 757.0 757.0 — 618.8 138.2 Non-agency residential mortgage-backed 24.0 24.0 — 24.0 — Commercial mortgage-backed 604.2 604.2 — 604.2 — Asset-backed 788.5 788.5 — 726.2 62.3 Total fixed maturity investments 7,794.2 7,794.2 1,765.2 5,828.5 200.5 Equity securities 202.3 202.3 202.3 — — Other invested assets (1) 820.0 820.0 — — — Total investments $ 8,816.5 $ 8,816.5 $ 1,967.5 $ 5,828.5 $ 200.5 Derivative assets: Foreign exchange contracts $ 1.5 $ 1.5 $ — $ 1.5 $ — Derivative liabilities: Foreign exchange contracts $ 0.4 $ 0.4 $ — $ 0.4 $ — Senior notes 1,293.7 $ 1,352.0 $ — $ 1,352.0 $ — Other long-term debt 23.1 $ 30.0 $ — $ 30.0 $ — December 31, 2015 Carrying Amount Total Fair Value Level 1 Level 2 Level 3 Fixed maturity investments: U.S. government and government agencies $ 1,434.0 $ 1,434.0 $ 1,396.4 $ 37.6 $ — Non-U.S. government and government agencies 556.8 556.8 — 556.8 — States, municipalities and political subdivisions 413.5 413.5 — 413.5 — Corporate debt: Financial institutions 1,275.4 1,275.4 — 1,275.4 — Industrials 1,308.1 1,308.1 — 1,308.1 — Utilities 118.9 118.9 — 118.9 — Mortgage-backed: Agency mortgage-backed 751.8 751.8 — 645.7 106.1 Non-agency residential mortgage-backed 34.0 34.0 — 34.0 — Commercial mortgage-backed 582.8 582.8 — 582.8 — Asset-backed 726.2 726.2 — 663.2 63.0 Total fixed maturity investments 7,201.5 7,201.5 1,396.4 5,636.0 169.1 Equity securities 403.0 403.0 403.0 — — Other invested assets (1) 840.2 840.2 — — — Total investments $ 8,444.7 $ 8,444.7 $ 1,799.4 $ 5,636.0 $ 169.1 Derivative assets: Foreign exchange contracts $ 0.1 $ 0.1 $ — $ 0.1 $ — Derivative liabilities: Foreign exchange contracts $ 3.0 $ 3.0 $ — $ 3.0 $ — Interest rate swaps $ 0.5 $ 0.5 $ — $ 0.5 $ — Senior notes $ 1,292.9 $ 1,337.9 $ — $ 1,337.9 $ — Other long-term debt $ 23.0 $ 27.7 $ — $ 27.7 $ — _______________________ (1) In accordance with U.S. GAAP, other invested assets, excluding other private securities, are measured at fair value using the net asset value per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy.
Fair value measurements using significant unobservable inputs (Level 3)	The following is a reconciliation of the beginning and ending balance of financial instruments using significant unobservable inputs (Level 3): Three Months Ended June 30, 2016 MBS CMBS Total mortgage-backed Asset-backed Equities Opening balance $ 146.1 $ — $ 146.1 $ 63.6 $ — Realized and unrealized gains included in net income 0.6 — 0.6 1.5 — Purchases — — 16.5 — Sales (8.5 ) — (8.5 ) (10.5 ) — Transfers into Level 3 from Level 2 — — — 0.5 — Transfers out of Level 3 into Level 2 (1) — — — (9.3 ) — Ending balance $ 138.2 $ — $ 138.2 $ 62.3 $ — Three Months Ended June 30, 2015 Opening balance $ 132.7 $ — $ 132.7 $ 92.9 $ 48.8 Realized and unrealized (losses) gains included in net income (2.4 ) — (2.4 ) (0.5 ) 9.0 Purchases 1.6 2.8 4.4 2.2 — Sales (35.3 ) — (35.3 ) (7.2 ) — Transfers into Level 3 from Level 2 — 0.3 0.3 17.4 — Transfers out of Level 3 into Level 2 (1) — — — (20.9 ) — Ending balance $ 96.6 $ 3.1 $ 99.7 $ 83.9 $ 57.8 Six Months Ended June 30, 2016 MBS CMBS Total mortgage-backed Asset-backed Equities Opening balance $ 106.1 $ — $ 106.1 $ 63.0 $ — Realized and unrealized gains (losses) included in net income 2.1 — 2.1 0.6 — Purchases 38.8 — 38.8 16.6 — Sales (10.3 ) — (10.3 ) (9.5 ) — Transfers into Level 3 from Level 2 1.5 — 1.5 7.9 — Transfers out of Level 3 into Level 2 (1) — — — (16.3 ) — Ending balance $ 138.2 $ — $ 138.2 $ 62.3 $ — Six Months Ended June 30, 2015 Opening balance $ 180.1 $ 1.7 $ 181.8 $ 55.4 $ 43.3 Realized and unrealized (losses) gains included in net income (1.1 ) 0.1 (1.0 ) (0.6 ) 14.5 Purchases 2.1 4.6 6.7 23.3 — Sales (84.5 ) (3.6 ) (88.1 ) (9.9 ) — Transfers into Level 3 from Level 2 — 0.3 0.3 43.9 — Transfers out of Level 3 into Level 2 (1) — — — (28.2 ) — Ending balance $ 96.6 $ 3.1 $ 99.7 $ 83.9 $ 57.8 _______________________ (1) Transfers out of Level 3 are primarily attributable to the availability of market observable information.

Reserve For Losses And Loss E24

Reserve For Losses And Loss Expenses (Tables)	6 Months Ended
	Jun. 30, 2016
Insurance Loss Reserves [Abstract]
Components of liabilty for unpaid losses and loss expenses	The reserve for losses and loss expenses consists of the following: June 30, December 31, Outstanding loss reserves $ 1,727.3 $ 1,678.5 Reserves for losses incurred but not reported 4,895.9 4,777.7 Reserve for losses and loss expenses $ 6,623.2 $ 6,456.2
Reconciliation of beginning and ending liability for unpaid losses and loss expenses	The table below is a reconciliation of the beginning and ending liability for unpaid losses and loss expenses. Losses incurred and paid are reflected net of reinsurance recoverables. Three Months Ended Six Months Ended 2016 2015 2016 2015 Gross liability at beginning of period $ 6,575.1 $ 5,905.1 $ 6,456.2 $ 5,881.2 Reinsurance recoverable at beginning of period (1,512.0 ) (1,350.3 ) (1,480.0 ) (1,340.3 ) Net liability at beginning of period 5,063.1 4,554.8 4,976.2 4,540.9 Acquisition of net reserve for losses and loss expenses — 257.0 — 257.0 Net losses incurred related to: Current year 403.3 453.3 801.1 842.2 Prior years (37.9 ) (21.8 ) (63.3 ) (85.5 ) Total incurred 365.4 431.5 737.8 756.7 Net paid losses related to: Current year 34.5 28.0 41.2 34.6 Prior years 280.9 285.8 563.4 578.9 Total paid 315.4 313.8 604.6 613.5 Foreign exchange revaluation (6.6 ) 1.3 (2.9 ) (10.3 ) Net liability at end of period 5,106.5 4,930.8 5,106.5 4,930.8 Reinsurance recoverable at end of period 1,516.7 1,433.1 1,516.7 1,433.1 Gross liability at end of period $ 6,623.2 $ 6,363.9 $ 6,623.2 $ 6,363.9

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2016
Stockholders' Equity Note [Abstract]
Issued share capital	The issued share capital consists of the following: June 30, December 31, Common shares issued and fully paid, 2016 and 2015: CHF 4.10 per share 93,586,418 95,523,230 Share capital at end of period $ 366.7 $ 386.7
Schedule of common stock outstanding roll forward	Six Months Ended June 30, 2016 Shares issued at beginning of period 95,523,230 Shares canceled (1,936,812 ) Total shares issued at end of period 93,586,418 Treasury shares issued at beginning of period 4,563,595 Shares repurchased 3,952,243 Shares issued out of treasury (456,558 ) Shares canceled (1,936,812 ) Total treasury shares at end of period 6,122,468 Total shares outstanding at end of period 87,463,950
Dividends paid	The Company paid the following dividends during the six months ended June 30, 2016 : Dividend Paid Dividend Per Share Total Amount Paid June 30, 2016 $ 0.260 $ 22.8 March 31, 2016 $ 0.260 $ 23.4
Share repurchases	The Company’s share repurchases were as follows: Three Months Ended Six Months Ended 2016 2015 2016 2015 Common shares repurchased 2,491,355 4,776,224 3,952,243 6,047,437 Total cost of shares repurchased $ 90.0 $ 194.4 $ 140.0 $ 245.3 Average price per share $ 36.12 $ 40.69 $ 35.42 $ 40.56

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Comparison of basic and diluted earnings per share	The following table sets forth the comparison of basic and diluted earnings per share: Three Months Ended Six Months Ended 2016 2015 2016 2015 Basic earnings per share: Net income $ 153.4 $ 9.5 $ 227.5 $ 133.8 Weighted average common shares outstanding 88,742,484 92,441,730 89,495,564 94,178,989 Basic earnings per share $ 1.73 $ 0.10 $ 2.54 $ 1.42 Three Months Ended Six Months Ended 2016 2015 2016 2015 Diluted earnings per share: Net income $ 153.4 $ 9.5 $ 227.5 $ 133.8 Weighted average common shares outstanding 88,742,484 92,441,730 89,495,564 94,178,989 Share equivalents: Stock options 829,584 1,075,735 832,432 1,102,252 RSUs and performance-based equity awards 443,336 452,938 479,038 534,653 Employee share purchase plan 25,105 13,823 23,780 14,561 Weighted average common shares and common share equivalents outstanding - diluted 90,040,509 93,984,226 90,830,814 95,830,455 Diluted earnings per share $ 1.70 $ 0.10 $ 2.50 $ 1.40

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Summary of segment results	The following tables provide a summary of the segment results: Three Months Ended June 30, 2016 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 508.4 $ 125.4 $ 166.5 $ 800.3 Net premiums written 330.8 88.2 159.1 578.1 Net premiums earned 329.6 94.1 179.2 602.9 Net losses and loss expenses (209.9 ) (61.1 ) (94.4 ) (365.4 ) Acquisition costs (37.4 ) (16.3 ) (33.7 ) (87.4 ) General and administrative expenses (56.8 ) (31.5 ) (16.4 ) (104.7 ) Underwriting income (loss) 25.5 (14.8 ) 34.7 45.4 Other insurance-related income 0.9 — 4.3 5.2 Other insurance-related expenses (0.6 ) — (1.1 ) (1.7 ) Segment income (loss) 25.8 (14.8 ) 37.9 48.9 Net investment income 55.8 Net realized investment gains 74.5 Amortization of intangible assets (2.5 ) Interest expense (19.9 ) Foreign exchange gain 2.9 Income before income taxes $ 159.7 Loss and loss expense ratio 63.7 % 64.9 % 52.7 % 60.6 % Acquisition cost ratio 11.4 % 17.3 % 18.8 % 14.5 % General and administrative expense ratio 17.2 % 33.5 % 9.1 % 17.4 % Expense ratio 28.6 % 50.8 % 27.9 % 31.9 % Combined ratio 92.3 % 115.7 % 80.6 % 92.5 % Three Months Ended June 30, 2015 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 517.5 $ 135.0 $ 173.5 $ 826.0 Net premiums written 372.2 69.3 162.2 603.7 Net premiums earned 328.6 102.6 215.2 646.4 Net losses and loss expenses (237.7 ) (65.8 ) (128.0 ) (431.5 ) Acquisition costs (34.2 ) (24.3 ) (42.1 ) (100.6 ) General and administrative expenses (58.2 ) (30.7 ) (19.5 ) (108.4 ) Underwriting (loss) income (1.5 ) (18.2 ) 25.6 5.9 Other insurance-related income 0.9 — — 0.9 Other insurance-related expenses (0.6 ) (0.6 ) — (1.2 ) Segment (loss) income (1.2 ) (18.8 ) 25.6 5.6 Net investment income 42.8 Net realized investment losses (20.2 ) Amortization of intangible assets (2.8 ) Interest expense (14.5 ) Foreign exchange loss (1.3 ) Income before income taxes $ 9.6 Loss and loss expense ratio 72.4 % 64.1 % 59.5 % 66.8 % Acquisition cost ratio 10.4 % 23.7 % 19.6 % 15.6 % General and administrative expense ratio 17.7 % 29.9 % 9.1 % 16.8 % Expense ratio 28.1 % 53.6 % 28.7 % 32.4 % Combined ratio 100.5 % 117.7 % 88.2 % 99.2 % Six Months Ended June 30, 2016 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 887.5 $ 241.0 $ 535.3 $ 1,663.8 Net premiums written 597.0 175.8 509.3 1,282.1 Net premiums earned 645.9 188.3 348.8 1,183.0 Net losses and loss expenses (426.2 ) (128.9 ) (182.7 ) (737.8 ) Acquisition costs (71.3 ) (34.2 ) (70.2 ) (175.7 ) General and administrative expenses (109.0 ) (60.6 ) (31.5 ) (201.1 ) Underwriting (loss) income 39.4 (35.4 ) 64.4 68.4 Other insurance-related income 1.5 — 4.2 5.7 Other insurance-related expenses (1.3 ) — (1.5 ) (2.8 ) Segment income 39.6 (35.4 ) 67.1 71.3 Net investment income 109.1 Net realized investment gains 93.4 Amortization of intangible assets (5.0 ) Interest expense (39.8 ) Foreign exchange gain 5.9 Income before income taxes $ 234.9 Loss and loss expense ratio 66.0 % 68.4 % 52.4 % 62.4 % Acquisition cost ratio 11.0 % 18.1 % 20.1 % 14.9 % General and administrative expense ratio 16.9 % 32.1 % 9.0 % 17.0 % Expense ratio 27.9 % 50.2 % 29.1 % 31.9 % Combined ratio 93.9 % 118.6 % 81.5 % 94.3 % Six Months Ended June 30, 2015 North American Insurance Global Markets Insurance Reinsurance Total Gross premiums written $ 898.2 $ 195.6 $ 612.8 $ 1,706.6 Net premiums written 669.1 112.2 594.9 1,376.2 Net premiums earned 641.5 152.7 420.7 1,214.9 Net losses and loss expenses (433.2 ) (86.3 ) (237.2 ) (756.7 ) Acquisition costs (65.3 ) (31.3 ) (82.7 ) (179.3 ) General and administrative expenses (117.5 ) (48.7 ) (39.3 ) (205.5 ) Underwriting income (loss) 25.5 (13.6 ) 61.5 73.4 Other insurance-related income 1.9 — — 1.9 Other insurance-related expenses (1.5 ) (1.6 ) — (3.1 ) Segment income (loss) 25.9 (15.2 ) 61.5 72.2 Net investment income 87.3 Net realized investment gains 24.8 Amortization of intangible assets (3.4 ) Interest expense (28.8 ) Foreign exchange loss (11.2 ) Income before income taxes $ 140.9 Loss and loss expense ratio 67.5 % 56.5 % 56.4 % 62.3 % Acquisition cost ratio 10.2 % 20.5 % 19.7 % 14.8 % General and administrative expense ratio 18.3 % 31.9 % 9.3 % 16.9 % Expense ratio 28.5 % 52.4 % 29.0 % 31.7 % Combined ratio 96.0 % 108.9 % 85.4 % 94.0 %
Analysis of gross written premium by geographic location	The following table shows an analysis of the Company’s gross premiums written by geographic location of the Company’s subsidiaries and branches. All intercompany premiums have been eliminated. Three Months Ended Six Months Ended 2016 2015 2016 2015 United States $ 495.6 $ 483.1 $ 1,020.0 $ 1,019.8 Bermuda 140.9 167.9 285.0 364.5 Asia Pacific 91.4 93.2 193.6 133.3 Europe 65.1 76.3 153.7 180.2 Canada 7.3 5.5 11.5 8.8 Total gross premiums written $ 800.3 $ 826.0 $ 1,663.8 $ 1,706.6
Net premiums earned by segment and line of business	The following table shows the Company's net premiums earned by line of business for each segment for each of the periods indicated. Three Months Ended Six Months Ended 2016 2015 2016 2015 North American Insurance: Professional liability $ 103.1 $ 94.7 $ 204.6 $ 183.5 Casualty 104.3 109.2 201.1 214.1 Programs 43.3 36.7 82.9 70.9 Property 34.6 42.5 68.3 83.9 Other specialty 28.1 17.3 53.3 32.9 Healthcare 16.2 28.2 35.7 56.2 Total 329.6 328.6 645.9 641.5 Global Markets Insurance: Other specialty 30.2 27.2 61.0 39.9 Casualty 22.2 31.0 45.8 37.0 Professional liability 25.5 26.1 49.0 49.3 Property 16.2 18.3 32.5 26.5 Total 94.1 102.6 188.3 152.7 Reinsurance: Property 83.4 104.8 167.8 209.1 Casualty 46.7 58.9 92.8 115.8 Specialty 49.1 51.5 88.2 95.8 Total 179.2 215.2 348.8 420.7 Total net premiums earned $ 602.9 $ 646.4 $ 1,183.0 $ 1,214.9

Condensed Consolidated Guaran28

Condensed Consolidated Guarantor Financial Statements (Tables)	6 Months Ended
	Jun. 30, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of condensed consolidating balance sheet	Unaudited Condensed Consolidating Balance Sheet: As of June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated ASSETS: Investments $ — $ — $ 8,936.3 $ — $ 8,936.3 Cash and cash equivalents 22.6 1.1 560.8 — 584.5 Insurance balances receivable — — 961.0 — 961.0 Funds held — — 279.1 — 279.1 Reinsurance recoverable — — 1,516.7 — 1,516.7 Reinsurance recoverable on paid losses — — 73.8 — 73.8 Net deferred acquisition costs — — 168.9 — 168.9 Goodwill and intangible assets — — 506.1 — 506.1 Balances receivable on sale of investments — — 114.6 — 114.6 Investments in subsidiaries 3,381.1 4,190.9 — (7,572.0 ) — Due from subsidiaries 186.3 275.6 11.3 (473.2 ) — Other assets 1.5 0.8 724.0 — 726.3 Total assets $ 3,591.5 $ 4,468.4 $ 13,852.6 $ (8,045.2 ) $ 13,867.3 LIABILITIES: Reserve for losses and loss expenses $ — $ — $ 6,623.2 $ — $ 6,623.2 Unearned premiums — — 1,822.1 — 1,822.1 Reinsurance balances payable — — 227.7 — 227.7 Balances due on purchases of investments — — 155.0 — 155.0 Senior notes — 1,293.7 — — 1,293.7 Other long-term debt — — 23.1 — 23.1 Due to subsidiaries 3.6 7.7 461.9 (473.2 ) — Other liabilities 3.4 21.4 113.2 — 138.0 Total liabilities 7.0 1,322.8 9,426.2 (473.2 ) 10,282.8 Total shareholders’ equity 3,584.5 3,145.6 4,426.4 (7,572.0 ) 3,584.5 Total liabilities and shareholders’ equity $ 3,591.5 $ 4,468.4 $ 13,852.6 $ (8,045.2 ) $ 13,867.3 As of December 31, 2015 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated ASSETS: Investments — — 8,571.2 — $ 8,571.2 Cash and cash equivalents 21.8 1.0 585.2 — 608.0 Insurance balances receivable — — 745.9 — 745.9 Funds held — — 640.8 — 640.8 Reinsurance recoverable — — 1,480.0 — 1,480.0 Reinsurance recoverable on paid losses — — 96.4 96.4 Net deferred acquisition costs — — 165.2 — 165.2 Goodwill and intangible assets — — 504.7 — 504.7 Balances receivable on sale of investments — — 36.9 — 36.9 Investments in subsidiaries 3,347.0 4,396.3 — (7,743.3 ) — Due from subsidiaries 173.1 36.4 16.8 (226.3 ) — Other assets 1.8 0.1 660.9 — 662.8 Total assets $ 3,543.7 $ 4,433.8 $ 13,504.0 $ (7,969.6 ) $ 13,511.9 LIABILITIES: Reserve for losses and loss expenses — — 6,456.2 — $ 6,456.2 Unearned premiums — — 1,683.3 — 1,683.3 Reinsurance balances payable — — 214.4 — 214.4 Balances due on purchases of investments — — 125.1 — 125.1 Senior notes — 1,292.9 — — 1,292.9 Other long-term debt — — 23.0 — 23.0 Due to subsidiaries 8.6 8.3 209.5 (226.4 ) — Other liabilities 2.6 22.2 159.7 — 184.5 Total liabilities 11.2 1,323.4 8,871.2 (226.4 ) 9,979.4 Total shareholders’ equity 3,532.5 3,110.4 4,632.8 (7,743.2 ) 3,532.5 Total liabilities and shareholders’ equity $ 3,543.7 $ 4,433.8 $ 13,504.0 $ (7,969.6 ) $ 13,511.9
Schedule of condensed consolidating income statement	Unaudited Condensed Consolidating Statement of Operations and Comprehensive Income: Three Months Ended June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated Net premiums earned $ — $ — $ 602.9 $ — $ 602.9 Net investment income — — 55.8 — 55.8 Net realized investment gains (losses) — — 74.5 — 74.5 Other income — — 5.2 — 5.2 Net losses and loss expenses — — (365.4 ) — (365.4 ) Acquisition costs — — (87.4 ) — (87.4 ) General and administrative expenses 2.0 (0.1 ) (106.6 ) — (104.7 ) Other expense — — (1.7 ) — (1.7 ) Amortization of intangible assets — — (2.5 ) — (2.5 ) Interest expense — (19.4 ) (0.5 ) — (19.9 ) Foreign exchange gain (loss) (0.1 ) — 3.0 — 2.9 Income tax (expense) benefit (1.0 ) — (5.3 ) — (6.3 ) Equity in earnings of consolidated subsidiaries 152.5 170.6 — (323.1 ) — NET INCOME (LOSS) $ 153.4 $ 151.1 $ 172.0 $ (323.1 ) $ 153.4 Other comprehensive loss 0.1 — 0.1 (0.1 ) 0.1 COMPREHENSIVE INCOME (LOSS) $ 153.5 $ 151.1 $ 172.1 $ (323.2 ) $ 153.5 Three Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated Net premiums earned $ — $ — $ 646.4 $ — $ 646.4 Net investment income — — 42.8 — 42.8 Net realized investment gains (losses) — — (20.2 ) — (20.2 ) Other income — — 0.9 — 0.9 Net losses and loss expenses — — (431.5 ) — (431.5 ) Acquisition costs — — (100.6 ) — (100.6 ) General and administrative expenses (10.2 ) (0.4 ) (97.8 ) — (108.4 ) Other expense — — (1.2 ) — (1.2 ) Amortization of intangible assets — — (2.8 ) — (2.8 ) Interest expense — (13.9 ) (0.6 ) — (14.5 ) Foreign exchange gain (loss) — — (1.3 ) — (1.3 ) Income tax (expense) benefit 0.6 — (0.7 ) — (0.1 ) Equity in earnings of consolidated subsidiaries 19.1 31.9 — (51.0 ) — NET INCOME (LOSS) $ 9.5 $ 17.6 $ 33.4 $ (51.0 ) $ 9.5 Other comprehensive loss (3.3 ) — (3.3 ) 3.3 (3.3 ) COMPREHENSIVE INCOME (LOSS) $ 6.2 $ 17.6 $ 30.1 $ (47.7 ) $ 6.2 Six Months Ended June 30, 2016 Allied World Guarantor) Allied World Issuer) Other Allied Subsidiaries Consolidating Adjustments Allied World Consolidated Net premiums earned $ — $ — $ 1,183.0 $ — $ 1,183.0 Net investment income — — 109.1 — 109.1 Net realized investment gains (losses) — — 93.4 — 93.4 Other income — — 5.7 — 5.7 Net losses and loss expenses — — (737.8 ) — (737.8 ) Acquisition costs — — (175.7 ) — (175.7 ) General and administrative expenses 2.6 0.4 (204.1 ) — (201.1 ) Other expense — — (2.8 ) — (2.8 ) Amortization of intangible assets — — (5.0 ) — (5.0 ) Interest expense — (38.8 ) (1.0 ) — (39.8 ) Foreign exchange gain (loss) (0.1 ) — 6.0 — 5.9 Income tax (expense) benefit (1.3 ) — (6.1 ) — (7.4 ) Equity in earnings of consolidated subsidiaries 226.3 266.5 — (492.8 ) — NET INCOME (LOSS) $ 227.5 $ 228.1 $ 264.7 $ (492.8 ) $ 227.5 Other comprehensive loss 3.3 — 3.3 (3.3 ) 3.3 COMPREHENSIVE INCOME (LOSS) $ 230.8 $ 228.1 $ 268.0 $ (496.1 ) $ 230.8 Six Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated Net premiums earned $ — $ — $ 1,214.9 $ — $ 1,214.9 Net investment income — — 87.3 — 87.3 Net realized investment gains (losses) — — 24.8 — 24.8 Other income — — 1.9 — 1.9 Net losses and loss expenses — — (756.7 ) — (756.7 ) Acquisition costs — — (179.3 ) — (179.3 ) General and administrative expenses (19.6 ) (0.2 ) (185.7 ) — (205.5 ) Other expense — — (3.1 ) — (3.1 ) Amortization of intangible assets — — (3.4 ) — (3.4 ) Interest expense — (27.7 ) (1.1 ) — (28.8 ) Foreign exchange gain (loss) — — (11.2 ) — (11.2 ) Income tax (expense) benefit (0.1 ) — (7.0 ) — (7.1 ) Equity in earnings of consolidated subsidiaries 153.5 175.6 — (329.1 ) — NET INCOME (LOSS) $ 133.8 $ 147.7 $ 181.4 $ (329.1 ) $ 133.8 Other comprehensive loss (3.3 ) — (3.3 ) 3.3 (3.3 ) COMPREHENSIVE INCOME (LOSS) $ 130.5 $ 147.7 $ 178.1 $ (325.8 ) $ 130.5
Schedule of condensed consolidating statement of cash flows	Unaudited Condensed Consolidating Statement of Cash Flows: Six Months Ended June 30, 2016 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES $ 183.4 $ 194.7 $ 552.5 $ (429.1 ) $ 501.5 CASH FLOWS PROVIDED BY (USED IN) INVESTING ACTIVITIES: Purchases of trading securities — — (3,257.8 ) — (3,257.8 ) Purchases of other invested assets — — (33.2 ) — (33.2 ) Sales of trading securities — — 2,932.2 — 2,932.2 Sales of other invested assets — — 37.3 — 37.3 Net cash paid for acquisitions — — (1.2 ) — (1.2 ) Other — — (19.5 ) — (19.5 ) Net cash provided by (used in) investing activities — — (342.2 ) — (342.2 ) CASH FLOWS PROVIDED BY (USED IN) FINANCING ACTIVITIES: Dividends paid (46.2 ) — — — (46.2 ) Intercompany dividend paid — (194.6 ) (234.5 ) 429.1 — Proceeds from the exercise of stock options 3.1 — — — 3.1 Share repurchases (139.5 ) — — — (139.5 ) Repayment of other long-term debt — — (0.2 ) — (0.2 ) Net cash provided by (used in) financing activities (182.6 ) (194.6 ) (234.7 ) 429.1 (182.8 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 0.8 0.1 (24.4 ) — (23.5 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 21.8 1.0 585.2 — 608.0 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 22.6 $ 1.1 $ 560.8 $ — $ 584.5 Six Months Ended June 30, 2015 Allied World Switzerland (Parent Guarantor) Allied World Bermuda (Subsidiary Issuer) Other Allied World Subsidiaries Consolidating Adjustments Allied World Switzerland Consolidated CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES: $ 278.8 $ 298.6 $ 471.9 $ (624.1 ) $ 425.2 CASH FLOWS PROVIDED BY (USED IN) INVESTING ACTIVITIES: Purchases of trading securities — — (2,854.8 ) — (2,854.8 ) Purchases of other invested assets — — (73.1 ) — (73.1 ) Sales of trading securities — — 2,953.6 — 2,953.6 Sales of other invested assets — — 85.5 — 85.5 Net cash paid for acquisitions — — (141.5 ) — (141.5 ) Other — — (44.1 ) — (44.1 ) Net cash provided by (used in) investing activities — — (74.4 ) — (74.4 ) CASH FLOWS PROVIDED BY (USED IN) FINANCING ACTIVITIES: Dividends paid (43.2 ) — — — (43.2 ) Intercompany dividends paid — (298.4 ) (325.7 ) 624.1 — Proceeds from the exercise of stock options 7.4 — — — 7.4 Proceeds from other long-term debt — — 3.9 — 3.9 Share repurchases (246.4 ) — — — (246.4 ) Net cash provided by (used in) financing activities (282.2 ) (298.4 ) (321.8 ) 624.1 (278.3 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS (3.4 ) 0.2 75.7 — 72.5 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 32.6 1.7 555.0 — 589.3 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 29.2 $ 1.9 $ 630.7 $ — $ 661.8

Investments (Schedule Of Tradin

Investments (Schedule Of Trading Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Equity securities and other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	$ 1,022.3	$ 1,243.2
Trading securities, Amortized Cost	972.3	1,166.2
Equity securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	202.3	403
Trading securities, Amortized Cost	205.3	395.3
Other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	820	840.2
Trading securities, Amortized Cost	767	770.9
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	7,794.2	7,201.5
Trading securities, Amortized Cost	7,769	7,290.6
U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,805.5	1,434
Trading securities, Amortized Cost	1,792.2	1,437.9
Non-U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	469.6	556.8
Trading securities, Amortized Cost	479.8	579.2
States, Municipalities And Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	504.6	413.5
Trading securities, Amortized Cost	476.4	396
Corporate Debt, Financial Institutions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,223.6	1,275.4
Trading securities, Amortized Cost	1,205.8	1,277.3
Corporate Debt, Industrials [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,476.8	1,308.1
Trading securities, Amortized Cost	1,461.5	1,345.6
Corporate Debt, Utilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	140.4	118.9
Trading securities, Amortized Cost	140.3	125.4
Agency mortgage-backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	757	751.8
Trading securities, Amortized Cost	742.1	745.4
Non-agency residential mortgage-backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	24	34
Trading securities, Amortized Cost	23.1	32.4
Commercial mortgage-backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	604.2	582.8
Trading securities, Amortized Cost	637	600.1
Asset-backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	788.5	726.2
Trading securities, Amortized Cost	$ 810.8	$ 751.1

Investments (Schedule Of Other

Investments (Schedule Of Other Investments) (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2016	Dec. 31, 2015
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 939.8	$ 966.7
Unfunded Commitments		639.4	613.8
Investments with redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		497.7	502
Investments without redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 442.1	464.7
Investments without redemption restrictions [Member] | Hedge Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption notice period		30 days
Total Fair Value [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 820	840.2
Unfunded Commitments		639.4	613.8
Total Fair Value [Member] | Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		497.6	447.4
Unfunded Commitments		639.4	613.8
Total Fair Value [Member] | Private Equity [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		248.8	236.4
Unfunded Commitments		245.7	231
Total Fair Value [Member] | Levered Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		218.4	205.9
Unfunded Commitments		200.6	179
Total Fair Value [Member] | Real Estate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		25.3	0
Unfunded Commitments		189.3	200
Total Fair Value [Member] | Distressed [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		5.1	5.1
Unfunded Commitments		3.8	3.8
Total Fair Value [Member] | Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		322.4	379
Unfunded Commitments		0	0
Total Fair Value [Member] | Distressed Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		168.5	215.6
Unfunded Commitments		0	0
Total Fair Value [Member] | Relative Value Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		81.8	105.4
Unfunded Commitments		0	0
Total Fair Value [Member] | Equity Long/Short [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		62.2	58
Unfunded Commitments		0	0
Total Fair Value [Member] | Fund of Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		9.9
Unfunded Commitments		0
Total Fair Value [Member] | High Yield Loan Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets			13.8
Unfunded Commitments			0
Total Fair Value [Member] | Investments with redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		497.7	502
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		497.6	447.4
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Private Equity [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 248.8	$ 236.4
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Private Equity [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		1 year	1 year
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Private Equity [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		7 years	7 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Levered Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 218.4	$ 205.9
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Levered Credit [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		4 years	4 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Levered Credit [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		8 years	8 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Real Estate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 25.3	$ 0
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Real Estate [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		7 years	7 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Real Estate [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated remaining restriction period		9 years	9 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Distressed [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 5.1	$ 5.1
Estimated remaining restriction period		2 years	2 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 0.1	$ 54.6
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Distressed Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 0.1	$ 54.6
Estimated remaining restriction period		2 years	2 years
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Relative Value Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 0	$ 0
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Equity Long/Short [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments with redemption restrictions [Member] | Fund of Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0
Total Fair Value [Member] | Investments with redemption restrictions [Member] | High Yield Loan Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets			0
Total Fair Value [Member] | Investments without redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		322.3	338.2
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Private Equity [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Levered Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Real Estate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Distressed [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		322.3	324.4
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Distressed Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 168.4	$ 161
Redemption frequency	[1]	Monthly	Monthly
Redemption notice period	[1]	90 days	90 days
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Relative Value Credit [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 81.8	$ 105.4
Redemption frequency	[1]	Quarterly	Quarterly
Redemption notice period	[1]	60 days	60 days
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Equity Long/Short [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 62.2	$ 58
Redemption frequency	[1]	Quarterly	Quarterly
Redemption notice period	[1]	45 days	45 days
Total Fair Value [Member] | Investments without redemption restrictions [Member] | Fund of Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 9.9
Redemption frequency	[1]	Annual
Redemption notice period	[1]	60 days
Total Fair Value [Member] | Investments without redemption restrictions [Member] | High Yield Loan Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets			$ 13.8
Redemption frequency	[1]		Monthly
Redemption notice period	[1]		30 days
Carrying Value [Member] | Other Private Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 119.8	$ 126.5
Unfunded Commitments		0	0
Carrying Value [Member] | Investments with redemption restrictions [Member] | Other Private Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		0	0
Carrying Value [Member] | Investments without redemption restrictions [Member] | Other Private Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other invested assets		$ 119.8	$ 126.5
[1]	The redemption frequency and notice periods only apply to the investments without redemption restrictions. Some or all of these investments may be subject to a gate as described below.

Investments (Schedule Of Net In

Investments (Schedule Of Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Investment Income [Line Items]
Net investment income	$ 55.8	$ 42.8	$ 109.1	$ 87.3
Fixed maturity investments [Member]
Net Investment Income [Line Items]
Net investment income	48.9	41.2	96.9	77.4
Equity securities [Member]
Net Investment Income [Line Items]
Net investment income	1.4	4.9	3.3	8.4
Other invested assets: hedge funds and private equity [Member]
Net Investment Income [Line Items]
Net investment income	7.6	4.6	12.3	13
Other invested assets: other private securities [Member]
Net Investment Income [Line Items]
Net investment income	1.7	(3.8)	4.7	(2.9)
Cash and cash equivalents [Member]
Net Investment Income [Line Items]
Net investment income	0.8	0.4	1.3	0.9
Expenses [Member]
Net Investment Income [Line Items]
Net investment income	$ (4.6)	$ (4.5)	$ (9.4)	$ (9.5)

Investments (Components Of Real

Investments (Components Of Realized Gains And Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Gain (Loss) on Investments [Line Items]
Gross realized gains on sale of invested assets	$ 46.1	$ 36.1	$ 100.2	$ 81.4
Gross realized losses on sale of invested assets	(26.9)	(10.1)	(68.7)	(23.1)
Net realized and unrealized losses on derivatives	0.1	13.9	(22.9)	2.3
Net realized investment gains (losses)	74.5	(20.2)	93.4	24.8
Fixed maturity investments, trading [Member]
Gain (Loss) on Investments [Line Items]
Mark-to-market changes	55.4	(52.7)	117.7	(27.2)
Equity securities, trading [Member]
Gain (Loss) on Investments [Line Items]
Mark-to-market changes	0.9	(0.3)	(14.2)	5.1
Other invested assets [Member]
Gain (Loss) on Investments [Line Items]
Mark-to-market changes	$ (1.1)	$ (7.1)	$ (18.7)	$ (13.7)

Investments (Pledged Assets) (D

Investments (Pledged Assets) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Revolving Credit Facility [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Maximum borrowing capacity	$ 200
Term of credit facility	5 years
Additional commitments subject to lender approval	$ 150
Compliance With Reinsurance Contract Provisions Or Insurance Laws [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Restricted cash and investments	2,873.4	$ 2,748.9
Pledged As Collateral For Letter Of Credit Facilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Restricted cash and investments	$ 587.1	$ 579.3

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
VIE - maximum exposure to loss		$ 984.8
Other invested assets [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other-than-temporary impairments	$ 6.3		$ 6.3
Minimum [Member] | Investments with redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction, Period in Effect		1 year
Minimum [Member] | Investments without redemption restrictions [Member] | Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption notice period		30 days
Gate trigger, percentage		15.00%
Maximum [Member] | Investments with redemption restrictions [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction, Period in Effect		3 years
Maximum [Member] | Investments without redemption restrictions [Member] | Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Gate trigger, percentage		25.00%

Derivative Instruments (Locatio

Derivative Instruments (Location and Amounts of Derivative Fair Values On The Condensed Consolidated Balance Sheets) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Asset Derivative Notional Amount	$ 83.4	$ 41.1
Asset Derivative Fair Value	1.5	0.1
Liability Derivative Notional Amount	48.6	573
Liability Derivative Fair Value	0.4	3.5
Foreign exchange contracts | Other assets
Derivatives, Fair Value [Line Items]
Asset Derivative Notional Amount	83.4	41.1
Asset Derivative Fair Value	1.5	0.1
Foreign exchange contracts | Accounts payable and accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivative Notional Amount	48.6	244.8
Liability Derivative Fair Value	0.4	3
Interest rate swaps | Other assets
Derivatives, Fair Value [Line Items]
Asset Derivative Notional Amount	0	0
Asset Derivative Fair Value	0	0
Interest rate swaps | Accounts payable and accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivative Notional Amount	0	328.2
Liability Derivative Fair Value	$ 0	$ 0.5

Derivative Instruments (Locat36

Derivative Instruments (Location and Amounts of Unrealized And Realized Gains (Losses) On Derivatives Recorded In The Condensed Consolidated Income Statements) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ 3.4	$ 15.1	$ (21.8)	$ (3.9)
Foreign exchange (loss) gain
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	3.3	1.2	1.1	(6.2)
Foreign exchange (loss) gain | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	3.3	1.2	1.1	(6.2)
Net realized investment gains
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	0.1	13.9	(22.9)	2.3
Net realized investment gains | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(0.4)	(0.3)	(15.3)	0.8
Net realized investment gains | Interest rate futures
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ 0.5	$ 14.2	$ (7.6)	$ 1.5

Fair Value Of Financial Instr37

Fair Value Of Financial Instruments (Schedule Of Fair Value Of Financial Instruments) (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		$ 7,794.2	$ 7,201.5
Equity securities		202.3	403
Other invested assets		939.8	966.7
Total investments		8,936.3	8,571.2
Senior notes		1,293.7	1,292.9
Other long-term debt		23.1	23
Total Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets		820	840.2
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		7,794.2	7,201.5
Equity securities		202.3	403
Other invested assets	[1]	820	840.2
Total investments		8,816.5	8,444.7
Senior notes		1,293.7	1,292.9
Other long-term debt		23.1	23
Fair Value, Measurements, Recurring [Member] | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1.5	0.1
Derivative liabilities		0.4	3
Fair Value, Measurements, Recurring [Member] | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0.5
Fair Value, Measurements, Recurring [Member] | U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,805.5	1,434
Fair Value, Measurements, Recurring [Member] | Non-U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		469.6	556.8
Fair Value, Measurements, Recurring [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		504.6	413.5
Fair Value, Measurements, Recurring [Member] | Corporate Debt, Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,223.6	1,275.4
Fair Value, Measurements, Recurring [Member] | Corporate Debt, Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,476.8	1,308.1
Fair Value, Measurements, Recurring [Member] | Corporate Debt, Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		140.4	118.9
Fair Value, Measurements, Recurring [Member] | Agency mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		757	751.8
Fair Value, Measurements, Recurring [Member] | Non-agency residential mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		24	34
Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		604.2	582.8
Fair Value, Measurements, Recurring [Member] | Asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		788.5	726.2
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,765.2	1,396.4
Equity securities		202.3	403
Other invested assets	[1]	0	0
Total investments		1,967.5	1,799.4
Senior notes		0	0
Other long-term debt		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,765.2	1,396.4
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Non-U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt, Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt, Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt, Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Agency mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Non-agency residential mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commercial mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		5,828.5	5,636
Equity securities		0	0
Other invested assets	[1]	0	0
Total investments		5,828.5	5,636
Senior notes		1,352	1,337.9
Other long-term debt		30	27.7
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1.5	0.1
Derivative liabilities		0.4	3
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0.5
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		40.3	37.6
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Non-U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		469.6	556.8
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		504.6	413.5
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt, Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,223.6	1,275.4
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt, Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,476.8	1,308.1
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt, Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		140.4	118.9
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		618.8	645.7
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Non-agency residential mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		24	34
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commercial mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		604.2	582.8
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		726.2	663.2
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		200.5	169.1
Equity securities		0	0
Other invested assets	[1]	0	0
Total investments		200.5	169.1
Senior notes		0	0
Other long-term debt		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Non-U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt, Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt, Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt, Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Agency mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		138.2	106.1
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Non-agency residential mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commercial mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		62.3	63
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		7,794.2	7,201.5
Equity securities		202.3	403
Other invested assets	[1]	820	840.2
Total investments		8,816.5	8,444.7
Senior notes		1,352	1,337.9
Other long-term debt		30	27.7
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1.5	0.1
Derivative liabilities		0.4	3
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0.5
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,805.5	1,434
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Non-U.S. Government And Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		469.6	556.8
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		504.6	413.5
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Corporate Debt, Financial Institutions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,223.6	1,275.4
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Corporate Debt, Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		1,476.8	1,308.1
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Corporate Debt, Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		140.4	118.9
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Agency mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		757	751.8
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Non-agency residential mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		24	34
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Commercial mortgage-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		604.2	582.8
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading fixed maturity investments		$ 788.5	$ 726.2
[1]	In accordance with U.S. GAAP, other invested assets, excluding other private securities, are measured at fair value using the net asset value per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy.

Fair Value Of Financial Instr38

Fair Value Of Financial Instruments (Schedule Of Fair Value Measurement Using Significant Unobservable Inputs Level Three) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		$ 146.1	$ 132.7	$ 106.1	$ 181.8
Realized and unrealized gains (losses) included in net income		0.6	(2.4)	2.1	(1)
Purchases		0	4.4	38.8	6.7
Sales		(8.5)	(35.3)	(10.3)	(88.1)
Transfers into Level 3 from Level 2		0	0.3	1.5	0.3
Transfers out of Level 3 to Level 2		0	0	0	0
Ending balance		138.2	99.7	138.2	99.7
Agency mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		146.1	132.7	106.1	180.1
Realized and unrealized gains (losses) included in net income		0.6	(2.4)	2.1	(1.1)
Purchases			1.6	38.8	2.1
Sales		(8.5)	(35.3)	(10.3)	(84.5)
Transfers into Level 3 from Level 2		0	0	1.5	0
Transfers out of Level 3 to Level 2		0	0	0	0
Ending balance		138.2	96.6	138.2	96.6
Commercial mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		0	0	0	1.7
Realized and unrealized gains (losses) included in net income		0	0	0	0.1
Purchases		0	2.8	0	4.6
Sales		0	0	0	(3.6)
Transfers into Level 3 from Level 2		0	0.3	0	0.3
Transfers out of Level 3 to Level 2		0	0	0	0
Ending balance		0	3.1	0	3.1
Asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		63.6	92.9	63	55.4
Realized and unrealized gains (losses) included in net income		1.5	(0.5)	0.6	(0.6)
Purchases		16.5	2.2	16.6	23.3
Sales		(10.5)	(7.2)	(9.5)	(9.9)
Transfers into Level 3 from Level 2		0.5	17.4	7.9	43.9
Transfers out of Level 3 to Level 2	[1]	(9.3)	(20.9)	(16.3)	(28.2)
Ending balance		62.3	83.9	62.3	83.9
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		0	48.8	0	43.3
Realized and unrealized gains (losses) included in net income		0	9	0	14.5
Purchases		0	0	0	0
Sales		0	0	0	0
Transfers into Level 3 from Level 2		0	0	0	0
Transfers out of Level 3 to Level 2	[1]	0	0	0	0
Ending balance		$ 0	$ 57.8	$ 0	$ 57.8
[1]	Transfers out of Level 3 are primarily attributable to the availability of market observable information.

Reserve For Losses And Loss E39

Reserve For Losses And Loss Expenses (Schedule Of Reserve For Losses And Loss Expenses) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Insurance Loss Reserves [Abstract]
Outstanding loss reserves	$ 1,727.3		$ 1,678.5
Reserves for losses incurred but not reported	4,895.9		4,777.7
Reserve for losses and loss expenses	$ 6,623.2	$ 6,575.1	$ 6,456.2	$ 6,363.9	$ 5,905.1	$ 5,881.2

Reserve For Losses And Loss E40

Reserve For Losses And Loss Expenses (Schedule Of Reconciliation Of Unpaid Losses And Loss Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Insurance Loss Reserves [Abstract]
Gross liability at beginning of year	$ 6,575.1	$ 5,905.1	$ 6,456.2	$ 5,881.2
Reinsurance recoverable at beginning of year	(1,512)	(1,350.3)	(1,480)	(1,340.3)
Net liability at beginning of year	5,063.1	4,554.8	4,976.2	4,540.9
Acquisition of net reserve for losses and loss expenses	0	257	0	257
Net losses incurred related to:
Current year	403.3	453.3	801.1	842.2
Prior years	(37.9)	(21.8)	(63.3)	(85.5)
Total incurred	365.4	431.5	737.8	756.7
Net paid losses related to:
Current year	34.5	28	41.2	34.6
Prior years	280.9	285.8	563.4	578.9
Total paid	315.4	313.8	604.6	613.5
Foreign exchange revaluation	(6.6)	1.3	(2.9)	(10.3)
Net liability at end of year	5,106.5	4,930.8	5,106.5	4,930.8
Reinsurance recoverable at end of year	1,516.7	1,433.1	1,516.7	1,433.1
Gross liability at end of year	6,623.2	6,363.9	6,623.2	6,363.9
Business Acquisition [Line Items]
Acquisition of net reserve for losses and loss expenses	$ 0	257	$ 0	257
Hong Kong And Singapore Operations Of Royal Sun Alliance Insurance Plc [Member]
Insurance Loss Reserves [Abstract]
Acquisition of net reserve for losses and loss expenses		252.8		252.8
Business Acquisition [Line Items]
Acquisition of net reserve for losses and loss expenses		252.8		252.8
Royal and Sun Alliance Labuan branch
Insurance Loss Reserves [Abstract]
Acquisition of net reserve for losses and loss expenses		4.2		4.2
Business Acquisition [Line Items]
Acquisition of net reserve for losses and loss expenses		$ 4.2		$ 4.2

Shareholders' Equity (Issued Sh

Shareholders' Equity (Issued Share Capital) (Details) $ in Millions	Jun. 30, 2016USD ($)shares	Jun. 30, 2016SFr / shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2015SFr / shares
Stockholders' Equity Note [Abstract]
Common shares issued and fully paid, 2016 and 2015: CHF 4.10 per share | shares	93,586,418		95,523,230
Common shares, par value | SFr / shares		SFr 4.1		SFr 4.1
Total share capital | $	$ 366.7		$ 386.7

Shareholders' Equity (Schedule

Shareholders' Equity (Schedule Of Common Stock Outstanding Roll Forward) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued at beginning of year			95,523,230
Shares cancelled, shares			(1,936,812)
Shares issued at end of year	93,586,418		93,586,418
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Treasury shares issued at beginning of year			4,563,595
Shares repurchased, shares	2,491,355	4,776,224	3,952,243	6,047,437
Shares issued out of treasury, shares			(456,558)
Shares cancelled, shares			(1,936,812)
Total treasury shares at end of year	6,122,468		6,122,468
Total shares outstanding at end of year	87,463,950		87,463,950

Shareholders' Equity (Schedul43

Shareholders' Equity (Schedule Of Dividends Paid) (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Dividends, Common Stock [Abstract]
Dividends paid per common share			$ 0.26	$ 0.225	$ 0.52	$ 0.45
Common shares
Dividends, Common Stock [Abstract]
Dividends paid per common share	$ 0.26	$ 0.260
Payment of quarterly dividends	$ 22.8	$ 23.4

Shareholders' Equity (Schedul44

Shareholders' Equity (Schedule Of Share Repurchases) (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 19, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 500
Shares repurchased, shares		2,491,355	4,776,224	3,952,243	6,047,437
Cost of shares repurchased		$ 90	$ 194.4	$ 140	$ 245.3
Shares repurchased, average price per share		$ 36.12	$ 40.69	$ 35.42	$ 40.56
Treasury shares held for issuance pursuant to equity-based compensation plans	3,000,000
Exor SA [Member]
Class of Stock [Line Items]
Shares repurchased, shares			4,053,537
Cost of shares repurchased			$ 164.4
Shares repurchased, average price per share			$ 40.546

Earnings Per Share (Comparison

Earnings Per Share (Comparison Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Basic earnings per share:
Net income	$ 153.4	$ 9.5	$ 227.5	$ 133.8
Weighted average common shares outstanding	88,742,484	92,441,730	89,495,564	94,178,989
Basic earnings per share	$ 1.73	$ 0.10	$ 2.54	$ 1.42
Diluted earnings per share:
Net income	$ 153.4	$ 9.5	$ 227.5	$ 133.8
Weighted average common shares outstanding	88,742,484	92,441,730	89,495,564	94,178,989
Share equivalents:
Warrants and options	829,584	1,075,735	832,432	1,102,252
RSUs and LTIP awards	443,336	452,938	479,038	534,653
Employee share purchase plan	25,105	13,823	23,780	14,561
Weighted average common shares and common share equivalents outstanding - diluted	90,040,509	93,984,226	90,830,814	95,830,455
Diluted earnings per share	$ 1.70	$ 0.10	$ 2.50	$ 1.40

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	229,999	0	235,085	0

Segment Information (Summary Of

Segment Information (Summary Of Segment Results) (Details) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2015segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 800.3	$ 826	$ 1,663.8	$ 1,706.6
Net premiums written	578.1	603.7	1,282.1	1,376.2
Net premiums earned	602.9	646.4	1,183	1,214.9
Net losses and loss expenses	(365.4)	(431.5)	(737.8)	(756.7)
Acquisition costs	(87.4)	(100.6)	(175.7)	(179.3)
General and administrative expenses	(104.7)	(108.4)	(201.1)	(205.5)
Underwriting income (loss)	45.4	5.9	68.4	73.4
Other insurance-related income	5.2	0.9	5.7	1.9
Other insurance-related expenses	(1.7)	(1.2)	(2.8)	(3.1)
Segment income (loss)	48.9	5.6	71.3	72.2
Net investment income	55.8	42.8	109.1	87.3
Net realized investment gains (losses)	74.5	(20.2)	93.4	24.8
Amortization of intangible assets	(2.5)	(2.8)	(5)	(3.4)
Interest expense	(19.9)	(14.5)	(39.8)	(28.8)
Foreign exchange loss	2.9	(1.3)	5.9	(11.2)
Income before income taxes	$ 159.7	$ 9.6	$ 234.9	$ 140.9
Loss and loss expense ratio	60.60%	66.80%	62.40%	62.30%
Acquisition cost ratio	14.50%	15.60%	14.90%	14.80%
General and administrative expense ratio	17.40%	16.80%	17.00%	16.90%
Expense ratio	31.90%	32.40%	31.90%	31.70%
Combined ratio	92.50%	99.20%	94.30%	94.00%
Number of operating segments | segments					3
Operating Segments [Member] | North American Insurance [Member]
Segment Reporting Information [Line Items]
Gross premiums written	$ 508.4	$ 517.5	$ 887.5	$ 898.2
Net premiums written	330.8	372.2	597	669.1
Net premiums earned	329.6	328.6	645.9	641.5
Net losses and loss expenses	(209.9)	(237.7)	(426.2)	(433.2)
Acquisition costs	(37.4)	(34.2)	(71.3)	(65.3)
General and administrative expenses	(56.8)	(58.2)	(109)	(117.5)
Underwriting income (loss)	25.5	(1.5)	39.4	25.5
Other insurance-related income	0.9	0.9	1.5	1.9
Other insurance-related expenses	(0.6)	(0.6)	(1.3)	(1.5)
Segment income (loss)	$ 25.8	$ (1.2)	$ 39.6	$ 25.9
Loss and loss expense ratio	63.70%	72.40%	66.00%	67.50%
Acquisition cost ratio	11.40%	10.40%	11.00%	10.20%
General and administrative expense ratio	17.20%	17.70%	16.90%	18.30%
Expense ratio	28.60%	28.10%	27.90%	28.50%
Combined ratio	92.30%	100.50%	93.90%	96.00%
Operating Segments [Member] | Global Markets Insurance [Member]
Segment Reporting Information [Line Items]
Gross premiums written	$ 125.4	$ 135	$ 241	$ 195.6
Net premiums written	88.2	69.3	175.8	112.2
Net premiums earned	94.1	102.6	188.3	152.7
Net losses and loss expenses	(61.1)	(65.8)	(128.9)	(86.3)
Acquisition costs	(16.3)	(24.3)	(34.2)	(31.3)
General and administrative expenses	(31.5)	(30.7)	(60.6)	(48.7)
Underwriting income (loss)	(14.8)	(18.2)	(35.4)	(13.6)
Other insurance-related income	0	0	0	0
Other insurance-related expenses	0	(0.6)	0	(1.6)
Segment income (loss)	$ (14.8)	$ (18.8)	$ (35.4)	$ (15.2)
Loss and loss expense ratio	64.90%	64.10%	68.40%	56.50%
Acquisition cost ratio	17.30%	23.70%	18.10%	20.50%
General and administrative expense ratio	33.50%	29.90%	32.10%	31.90%
Expense ratio	50.80%	53.60%	50.20%	52.40%
Combined ratio	115.70%	117.70%	118.60%	108.90%
Operating Segments [Member] | Reinsurance [Member]
Segment Reporting Information [Line Items]
Gross premiums written	$ 166.5	$ 173.5	$ 535.3	$ 612.8
Net premiums written	159.1	162.2	509.3	594.9
Net premiums earned	179.2	215.2	348.8	420.7
Net losses and loss expenses	(94.4)	(128)	(182.7)	(237.2)
Acquisition costs	(33.7)	(42.1)	(70.2)	(82.7)
General and administrative expenses	(16.4)	(19.5)	(31.5)	(39.3)
Underwriting income (loss)	34.7	25.6	64.4	61.5
Other insurance-related income	4.3	0	4.2	0
Other insurance-related expenses	(1.1)	0	(1.5)	0
Segment income (loss)	$ 37.9	$ 25.6	$ 67.1	$ 61.5
Loss and loss expense ratio	52.70%	59.50%	52.40%	56.40%
Acquisition cost ratio	18.80%	19.60%	20.10%	19.70%
General and administrative expense ratio	9.10%	9.10%	9.00%	9.30%
Expense ratio	27.90%	28.70%	29.10%	29.00%
Combined ratio	80.60%	88.20%	81.50%	85.40%

Segment Information (Gross Prem

Segment Information (Gross Premiums Written By Geographic Location) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 800.3	$ 826	$ 1,663.8	$ 1,706.6
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	495.6	483.1	1,020	1,019.8
Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	140.9	167.9	285	364.5
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	91.4	93.2	193.6	133.3
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	65.1	76.3	153.7	180.2
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	7.3	5.5	11.5	8.8
Switzerland
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 2.5	$ 4.3	$ 38.1	$ 44.7

Segment Information (Net Premiu

Segment Information (Net Premiums Earned By Line of Business) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Total net premiums earned	$ 602.9	$ 646.4	$ 1,183	$ 1,214.9
Operating Segments [Member] | North American Insurance [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	329.6	328.6	645.9	641.5
Operating Segments [Member] | North American Insurance [Member] | Professional Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	103.1	94.7	204.6	183.5
Operating Segments [Member] | North American Insurance [Member] | General Casualty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	104.3	109.2	201.1	214.1
Operating Segments [Member] | North American Insurance [Member] | Programs [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	43.3	36.7	82.9	70.9
Operating Segments [Member] | North American Insurance [Member] | General Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	34.6	42.5	68.3	83.9
Operating Segments [Member] | North American Insurance [Member] | Other specialty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	28.1	17.3	53.3	32.9
Operating Segments [Member] | North American Insurance [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	16.2	28.2	35.7	56.2
Operating Segments [Member] | Global Markets Insurance [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	94.1	102.6	188.3	152.7
Operating Segments [Member] | Global Markets Insurance [Member] | Professional Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	25.5	26.1	49	49.3
Operating Segments [Member] | Global Markets Insurance [Member] | General Casualty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	22.2	31	45.8	37
Operating Segments [Member] | Global Markets Insurance [Member] | General Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	16.2	18.3	32.5	26.5
Operating Segments [Member] | Global Markets Insurance [Member] | Other specialty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	30.2	27.2	61	39.9
Operating Segments [Member] | Reinsurance [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	179.2	215.2	348.8	420.7
Operating Segments [Member] | Reinsurance [Member] | Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	83.4	104.8	167.8	209.1
Operating Segments [Member] | Reinsurance [Member] | Casualty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	46.7	58.9	92.8	115.8
Operating Segments [Member] | Reinsurance [Member] | Specialty [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	$ 49.1	$ 51.5	$ 88.2	$ 95.8

Condensed Consolidated Guaran50

Condensed Consolidated Guarantor Financial Statements (Schedule Of Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
ASSETS:
Investments	$ 8,936.3		$ 8,571.2
Cash and cash equivalents	584.5		608	$ 661.8		$ 589.3
Insurance balances receivable	961		745.9
Funds held	279.1		640.8
Reinsurance recoverable	1,516.7	$ 1,512	1,480	1,433.1	$ 1,350.3	1,340.3
Reinsurance recoverable on paid losses	73.8		96.4
Net deferred acquisition costs	168.9		165.2
Goodwill and intangible assets	506.1		504.7
Balances receivable on sale of investments	114.6		36.9
Investments in subsidiaries	0		0
Due from subsidiaries	0		0
Other assets	726.3		662.8
Total assets	13,867.3		13,511.9
LIABILITIES:
Reserve for losses and loss expenses	6,623.2	$ 6,575.1	6,456.2	6,363.9	$ 5,905.1	5,881.2
Unearned premiums	1,822.1		1,683.3
Reinsurance balances payable	227.7		214.4
Balances due on purchases of investments	155		125.1
Senior notes	1,293.7		1,292.9
Other long-term debt	23.1		23
Due to subsidiaries	0		0
Other liabilities	138		184.5
Total liabilities	10,282.8		9,979.4
Total shareholders’ equity	3,584.5		3,532.5	3,624.7		3,778.2
Total liabilities and shareholders’ equity	$ 13,867.3		13,511.9
Percentage ownership of Subsidiary Issuer	100.00%
Consolidating Adjustments [Member]
ASSETS:
Investments	$ 0		0
Cash and cash equivalents	0		0	0		0
Insurance balances receivable	0		0
Funds held	0		0
Reinsurance recoverable	0		0
Reinsurance recoverable on paid losses	0
Net deferred acquisition costs	0		0
Goodwill and intangible assets	0		0
Balances receivable on sale of investments	0		0
Investments in subsidiaries	(7,572)		(7,743.3)
Due from subsidiaries	(473.2)		(226.3)
Other assets	0		0
Total assets	(8,045.2)		(7,969.6)
LIABILITIES:
Reserve for losses and loss expenses	0		0
Unearned premiums	0		0
Reinsurance balances payable	0		0
Balances due on purchases of investments	0		0
Senior notes	0		0
Other long-term debt	0		0
Due to subsidiaries	(473.2)		(226.4)
Other liabilities	0		0
Total liabilities	(473.2)		(226.4)
Total shareholders’ equity	(7,572)		(7,743.2)
Total liabilities and shareholders’ equity	(8,045.2)		(7,969.6)
Allied World Switzerland (Parent Guarantor) [Member]
ASSETS:
Investments	0		0
Cash and cash equivalents	22.6		21.8	29.2		32.6
Insurance balances receivable	0		0
Funds held	0		0
Reinsurance recoverable	0		0
Reinsurance recoverable on paid losses	0		0
Net deferred acquisition costs	0		0
Goodwill and intangible assets	0		0
Balances receivable on sale of investments	0		0
Investments in subsidiaries	3,381.1		3,347
Due from subsidiaries	186.3		173.1
Other assets	1.5		1.8
Total assets	3,591.5		3,543.7
LIABILITIES:
Reserve for losses and loss expenses	0		0
Unearned premiums	0		0
Reinsurance balances payable	0		0
Balances due on purchases of investments	0		0
Senior notes	0		0
Other long-term debt	0		0
Due to subsidiaries	3.6		8.6
Other liabilities	3.4		2.6
Total liabilities	7		11.2
Total shareholders’ equity	3,584.5		3,532.5
Total liabilities and shareholders’ equity	3,591.5		3,543.7
Allied World Bermuda (Subsidiary Issuer) [Member]
ASSETS:
Investments	0		0
Cash and cash equivalents	1.1		1	1.9		1.7
Insurance balances receivable	0		0
Funds held	0		0
Reinsurance recoverable	0		0
Reinsurance recoverable on paid losses	0		0
Net deferred acquisition costs	0		0
Goodwill and intangible assets	0		0
Balances receivable on sale of investments	0		0
Investments in subsidiaries	4,190.9		4,396.3
Due from subsidiaries	275.6		36.4
Other assets	0.8		0.1
Total assets	4,468.4		4,433.8
LIABILITIES:
Reserve for losses and loss expenses	0		0
Unearned premiums	0		0
Reinsurance balances payable	0		0
Balances due on purchases of investments	0		0
Senior notes	1,293.7		1,292.9
Other long-term debt	0		0
Due to subsidiaries	7.7		8.3
Other liabilities	21.4		22.2
Total liabilities	1,322.8		1,323.4
Total shareholders’ equity	3,145.6		3,110.4
Total liabilities and shareholders’ equity	4,468.4		4,433.8
Other Allied World Subsidiaries [Member]
ASSETS:
Investments	8,936.3		8,571.2
Cash and cash equivalents	560.8		585.2	$ 630.7		$ 555
Insurance balances receivable	961		745.9
Funds held	279.1		640.8
Reinsurance recoverable	1,516.7		1,480
Reinsurance recoverable on paid losses	73.8		96.4
Net deferred acquisition costs	168.9		165.2
Goodwill and intangible assets	506.1		504.7
Balances receivable on sale of investments	114.6		36.9
Investments in subsidiaries	0		0
Due from subsidiaries	11.3		16.8
Other assets	724		660.9
Total assets	13,852.6		13,504
LIABILITIES:
Reserve for losses and loss expenses	6,623.2		6,456.2
Unearned premiums	1,822.1		1,683.3
Reinsurance balances payable	227.7		214.4
Balances due on purchases of investments	155		125.1
Senior notes	0		0
Other long-term debt	23.1		23
Due to subsidiaries	461.9		209.5
Other liabilities	113.2		159.7
Total liabilities	9,426.2		8,871.2
Total shareholders’ equity	4,426.4		4,632.8
Total liabilities and shareholders’ equity	$ 13,852.6		$ 13,504

Condensed Consolidated Guaran51

Condensed Consolidated Guarantor Financial Statements (Schedule Of Condensed Consolidating Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Income Statements, Captions [Line Items]
Net premiums earned	$ 602.9	$ 646.4	$ 1,183	$ 1,214.9
Net investment income	55.8	42.8	109.1	87.3
Net realized investment gains (losses)	74.5	(20.2)	93.4	24.8
Other insurance-related income	5.2	0.9	5.7	1.9
Net losses and loss expenses	(365.4)	(431.5)	(737.8)	(756.7)
Acquisition costs	(87.4)	(100.6)	(175.7)	(179.3)
General and administrative expenses	(104.7)	(108.4)	(201.1)	(205.5)
Other insurance-related expenses	(1.7)	(1.2)	(2.8)	(3.1)
Amortization of intangible assets	(2.5)	(2.8)	(5)	(3.4)
Interest expense	(19.9)	(14.5)	(39.8)	(28.8)
Foreign exchange loss	2.9	(1.3)	5.9	(11.2)
Income tax (expense) benefit	(6.3)	(0.1)	(7.4)	(7.1)
Equity in earnings of consolidated subsidiaries	0	0	0	0
NET INCOME	153.4	9.5	227.5	133.8
Other comprehensive loss	0.1	(3.3)	3.3	(3.3)
COMPREHENSIVE INCOME (LOSS)	153.5	6.2	230.8	130.5
Consolidating Adjustments [Member]
Condensed Income Statements, Captions [Line Items]
Net premiums earned	0	0	0	0
Net investment income	0	0	0	0
Net realized investment gains (losses)	0	0	0	0
Other insurance-related income	0	0	0	0
Net losses and loss expenses	0	0	0	0
Acquisition costs	0	0	0	0
General and administrative expenses	0	0	0	0
Other insurance-related expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Interest expense	0	0	0	0
Foreign exchange loss	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Equity in earnings of consolidated subsidiaries	(323.1)	(51)	(492.8)	(329.1)
NET INCOME	(323.1)	(51)	(492.8)	(329.1)
Other comprehensive loss	(0.1)	3.3	(3.3)	3.3
COMPREHENSIVE INCOME (LOSS)	(323.2)	(47.7)	(496.1)	(325.8)
Allied World Switzerland (Parent Guarantor) [Member]
Condensed Income Statements, Captions [Line Items]
Net premiums earned	0	0	0	0
Net investment income	0	0	0	0
Net realized investment gains (losses)	0	0	0	0
Other insurance-related income	0	0	0	0
Net losses and loss expenses	0	0	0	0
Acquisition costs	0	0	0	0
General and administrative expenses	2	(10.2)	2.6	(19.6)
Other insurance-related expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Interest expense	0	0	0	0
Foreign exchange loss	(0.1)	0	(0.1)	0
Income tax (expense) benefit	(1)	0.6	(1.3)	(0.1)
Equity in earnings of consolidated subsidiaries	152.5	19.1	226.3	153.5
NET INCOME	153.4	9.5	227.5	133.8
Other comprehensive loss	0.1	(3.3)	3.3	(3.3)
COMPREHENSIVE INCOME (LOSS)	153.5	6.2	230.8	130.5
Allied World Bermuda (Subsidiary Issuer) [Member]
Condensed Income Statements, Captions [Line Items]
Net premiums earned	0	0	0	0
Net investment income	0	0	0	0
Net realized investment gains (losses)	0	0	0	0
Other insurance-related income	0	0	0	0
Net losses and loss expenses	0	0	0	0
Acquisition costs	0	0	0	0
General and administrative expenses	(0.1)	(0.4)	0.4	(0.2)
Other insurance-related expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Interest expense	(19.4)	(13.9)	(38.8)	(27.7)
Foreign exchange loss	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Equity in earnings of consolidated subsidiaries	170.6	31.9	266.5	175.6
NET INCOME	151.1	17.6	228.1	147.7
Other comprehensive loss	0	0	0	0
COMPREHENSIVE INCOME (LOSS)	151.1	17.6	228.1	147.7
Other Allied World Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net premiums earned	602.9	646.4	1,183	1,214.9
Net investment income	55.8	42.8	109.1	87.3
Net realized investment gains (losses)	74.5	(20.2)	93.4	24.8
Other insurance-related income	5.2	0.9	5.7	1.9
Net losses and loss expenses	(365.4)	(431.5)	(737.8)	(756.7)
Acquisition costs	(87.4)	(100.6)	(175.7)	(179.3)
General and administrative expenses	(106.6)	(97.8)	(204.1)	(185.7)
Other insurance-related expenses	(1.7)	(1.2)	(2.8)	(3.1)
Amortization of intangible assets	(2.5)	(2.8)	(5)	(3.4)
Interest expense	(0.5)	(0.6)	(1)	(1.1)
Foreign exchange loss	3	(1.3)	6	(11.2)
Income tax (expense) benefit	(5.3)	(0.7)	(6.1)	(7)
Equity in earnings of consolidated subsidiaries	0	0	0	0
NET INCOME	172	33.4	264.7	181.4
Other comprehensive loss	0.1	(3.3)	3.3	(3.3)
COMPREHENSIVE INCOME (LOSS)	$ 172.1	$ 30.1	$ 268	$ 178.1

Condensed Consolidated Guaran52

Condensed Consolidated Guarantor Financial Statements (Schedule Of Condensed Consolidating Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Condensed Cash Flow Statements, Captions [Line Items]
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:	$ 501.5	$ 425.2
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	(3,257.8)	(2,854.8)
Purchases of other invested assets	(33.2)	(73.1)
Sales of trading securities	2,932.2	2,953.6
Sales of other invested assets	37.3	85.5
Net cash paid for acquisitions	(1.2)	(141.5)
Other	(19.5)	(44.1)
Net cash used in investing activities	(342.2)	(74.4)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	(46.2)	(43.2)
Intercompany dividend paid	0	0
Proceeds from the exercise of stock options	3.1	7.4
Share repurchases	(139.5)	(246.4)
Repayment of other long-term debt	(0.2)	0
Proceeds from other long-term debt	0	3.9
Net cash used in financing activities	(182.8)	(278.3)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(23.5)	72.5
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	608	589.3
CASH AND CASH EQUIVALENTS, END OF PERIOD	584.5	661.8
Consolidating Adjustments [Member]
Condensed Cash Flow Statements, Captions [Line Items]
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:	(429.1)	(624.1)
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	0	0
Purchases of other invested assets	0	0
Sales of trading securities	0	0
Sales of other invested assets	0	0
Net cash paid for acquisitions	0	0
Other	0	0
Net cash used in investing activities	0	0
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	0	0
Intercompany dividend paid	429.1	624.1
Proceeds from the exercise of stock options	0	0
Share repurchases	0	0
Repayment of other long-term debt	0
Proceeds from other long-term debt		0
Net cash used in financing activities	429.1	624.1
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	0
Allied World Switzerland (Parent Guarantor) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:	183.4	278.8
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	0	0
Purchases of other invested assets	0	0
Sales of trading securities	0	0
Sales of other invested assets	0	0
Net cash paid for acquisitions	0	0
Other	0	0
Net cash used in investing activities	0	0
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	(46.2)	(43.2)
Intercompany dividend paid	0	0
Proceeds from the exercise of stock options	3.1	7.4
Share repurchases	(139.5)	(246.4)
Repayment of other long-term debt	0
Proceeds from other long-term debt		0
Net cash used in financing activities	(182.6)	(282.2)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	0.8	(3.4)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	21.8	32.6
CASH AND CASH EQUIVALENTS, END OF PERIOD	22.6	29.2
Allied World Bermuda (Subsidiary Issuer) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:	194.7	298.6
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	0	0
Purchases of other invested assets	0	0
Sales of trading securities	0	0
Sales of other invested assets	0	0
Net cash paid for acquisitions	0	0
Other	0	0
Net cash used in investing activities	0	0
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	0	0
Intercompany dividend paid	(194.6)	(298.4)
Proceeds from the exercise of stock options	0	0
Share repurchases	0	0
Repayment of other long-term debt	0
Proceeds from other long-term debt		0
Net cash used in financing activities	(194.6)	(298.4)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	0.1	0.2
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1	1.7
CASH AND CASH EQUIVALENTS, END OF PERIOD	1.1	1.9
Other Allied World Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:	552.5	471.9
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	(3,257.8)	(2,854.8)
Purchases of other invested assets	(33.2)	(73.1)
Sales of trading securities	2,932.2	2,953.6
Sales of other invested assets	37.3	85.5
Net cash paid for acquisitions	(1.2)	(141.5)
Other	(19.5)	(44.1)
Net cash used in investing activities	(342.2)	(74.4)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	0	0
Intercompany dividend paid	(234.5)	(325.7)
Proceeds from the exercise of stock options	0	0
Share repurchases	0	0
Repayment of other long-term debt	(0.2)
Proceeds from other long-term debt		3.9
Net cash used in financing activities	(234.7)	(321.8)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(24.4)	75.7
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	585.2	555
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 560.8	$ 630.7

Condensed Consolidated Guaran53

Condensed Consolidated Guarantor Financial Statements (Notes to Consolidated Guarantor Financial Statements) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries	$ 194.6	$ 298.4