Argo Group International (ARGO-PA) 10-Q 8 May 20 2020 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2020	May 06, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	1-15259
Entity Registrant Name	ARGO GROUP INTERNATIONAL HOLDINGS, LTD.
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	98-0214719
Entity Address, Address Line One	110 Pitts Bay Road
Entity Address, City or Town	Pembroke
Entity Address, Postal Zip Code	HM08
Entity Address, Country	BM
City Area Code	441
Local Phone Number	296-5858
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		34,634,776
Entity Central Index Key	0001091748
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value of $1.00 per share
Trading Symbol	ARGO
Security Exchange Name	NYSE
Guarantee of Argo Group U.S., Inc. 6.500% Senior Notes due 2042 [Member]
Document Information [Line Items]
Title of 12(b) Security	Guarantee of Argo Group U.S., Inc.  6.500% Senior Notes due 2042
Trading Symbol	ARGD
Security Exchange Name	NYSE

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	[1]
Investments:
Fixed maturities available-for-sale, at fair value (cost: 2020 - $3,634.4, 2019 - $3,605.0; allowance for expected credit losses: 2020 - $31.6)	$ 3,523.5	$ 3,633.5
Equity securities, at fair value (cost: 2020 - $170.6; 2019 - $122.8)	132.9	124.4
Other investments (cost: 2020 - $422.5; 2019 - $482.5)	422.4	496.5
Short-term investments, at fair value (cost: 2020 - $732.7; 2019 - $844.8)	732.6	845
Total investments	4,811.4	5,099.4
Cash	158.7	137.8
Accrued investment income	23.2	25.7
Premiums receivable	739.1	688.2
Reinsurance recoverables	2,820.9	3,104.6
Goodwill	161.4	161.4
Intangible assets, net of accumulated amortization	91.5	91.8
Deferred tax asset, net	44.5	6.1
Deferred acquisition costs, net	158	160.2
Ceded unearned premiums	652.9	545
Operating lease right-of-use assets	89.1	91.8
Other assets	435.4	387.1
Assets held for sale	15.2	15.4
Total assets	10,201.3	10,514.5
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	5,067.6	5,157.6
Unearned premiums	1,460	1,410.9
Accrued underwriting expenses and other liabilities	185.3	226
Ceded reinsurance payable, net	1,094.8	1,203.1
Funds held	60	50.6
Senior unsecured fixed rate notes	140	140
Other indebtedness	180	181.3
Junior subordinated debentures	257.5	257.4
Current income taxes payable, net	17.7	0.8
Operating lease liabilities	101.6	105.7
Total liabilities	8,564.5	8,733.4
Commitments and contingencies (Note 14)
Shareholders' equity:
Common shares - $1.00 par, 500,000,000 shares authorized; 45,867,812 and 45,698,470 shares issued at March 31, 2020 and December 31, 2019, respectively	45.9	45.7
Additional paid-in capital	1,374.2	1,376.6
Treasury shares (11,315,889 shares at March 31, 2020 and December 31, 2019, respectively)	(455.1)	(455.1)
Retained earnings	773.7	811.1
Accumulated other comprehensive (loss) income, net of taxes	(101.9)	2.8
Total shareholders' equity	1,636.8	1,781.1
Total liabilities and shareholders' equity	$ 10,201.3	$ 10,514.5
[1]	Derived from audited consolidated financial statements.

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturities available-for-sale, cost	$ 3,634.4	$ 3,605
Allowance for Credit Losses	31.6	0
Equity securities, cost	170.6	122.8
Other investments, cost	422.5	482.5
Short-term investments, cost	$ 732.7	$ 844.8
Common shares, par value (in dollars per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	500,000,000	500,000,000
Common shares, shares issued (in shares)	45,867,812	45,698,470
Treasury shares (in shares)	11,315,889	11,315,889

Condensed Consolidated Statemen

Condensed Consolidated Statements of (Loss) Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Premiums and other revenue:
Earned premiums	$ 435	$ 420.5
Net investment income	35.5	33.9
Fee and other income	2.1	2.3
Net realized investment (losses) gains:
Net realized investment gains (losses)	27.9	(1.7)
Change in fair value of equity securities	(39.3)	54.2
Credit losses on fixed maturity securities	(24.7)	0
Net realized investment (losses) gains	(36.1)	52.5
Total revenue	436.5	509.2
Expenses:
Losses and loss adjustment expenses	280.9	237.9
Underwriting, acquisition and insurance expenses	168	160.2
Other corporate expenses	3.3	0.5
Interest expense	7.7	8.5
Fee and other expense	1.2	1.3
Foreign currency exchange (gains) loss	(3)	0.7
Total expenses	458.1	409.1
(Loss) income before income taxes	(21.6)	100.1
Income tax (benefit) provision	(2.8)	8.9
Net (loss) income	$ (18.8)	$ 91.2
Net (loss) income per common share:
Basic (in dollars per share)	$ (0.55)	$ 2.68
Diluted (in dollars per share)	(0.55)	2.63
Dividends declared per common share (in dollars per share)	$ 0.31	$ 0.31
Weighted average common shares:
Basic (in shares)	34,469,516	33,984,329
Diluted (in shares)	34,469,516	34,737,939
Net realized investment (losses) gains before other-than-temporary impairment losses	$ (36.1)	$ 56.8
Other-than-temporary impairment losses recognized in earnings:
Other-than-temporary impairment losses on fixed maturities	0	(4.3)
Impairment losses recognized in earnings	0	(4.3)
Net realized investment (losses) gains	$ 27.9	$ (1.7)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (18.8)	$ 91.2
Other comprehensive income (loss):
Foreign currency translation adjustments	(3.4)	0.2
Unrealized (losses) gains on securities:
(Losses) gains arising during the year	(122.8)	56.8
Reclassification adjustment for (gains) losses included in net income	(3.4)	3.1
Other comprehensive (loss) income before tax	(129.6)	60.1
Income tax provision related to other comprehensive income:
(Losses) gain arising during the year	(21.1)	9.1
Reclassification adjustment for losses (gains) included in net income	1.9	0.5
Income tax (benefit) provision related to other comprehensive income	(19.2)	9.6
Other comprehensive (loss) income, net of tax	(110.4)	50.5
Comprehensive (loss) income	$ (129.2)	$ 141.7

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total		Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Shares [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) Member]
Beginning Balance at Dec. 31, 2018	$ 1,746.7		$ 45.3	$ 1,372	$ (455.1)	$ 862.6	$ (78.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	91.2					91.2
Other comprehensive income (loss) - change in fair value of fixed maturities, net of taxes	50.3						50.3
Other comprehensive income (loss) - other	0.2						0.2
Activity under stock incentive plans	4.2		0.1	4.1
Retirement of common shares (tax payments on equity compensation)	(1.6)		0	(1.6)
Employee stock purchase plan	0.4			0.4
Cash dividends declared - common shares	(10.8)					(10.8)
Ending Balance at Mar. 31, 2019	1,880.6		45.4	1,374.9	(455.1)	943	(27.6)
Beginning Balance at Dec. 31, 2019	1,781.1	[1]	45.7	1,376.6	(455.1)	811.1	2.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(18.8)					(18.8)
Other comprehensive income (loss) - change in fair value of fixed maturities, net of taxes	(107)						(107)
Other comprehensive income (loss) - other	(3.4)						(3.4)
Activity under stock incentive plans	3.1		0.3	2.8
Retirement of common shares (tax payments on equity compensation)	(5.8)		(0.1)	(5.7)
Employee stock purchase plan	0.5			0.5
Cash dividends declared - common shares	(10.7)					(10.7)
Ending Balance at Mar. 31, 2020	$ 1,636.8		$ 45.9	$ 1,374.2	$ (455.1)	$ 773.7	$ (101.9)
[1]	Derived from audited consolidated financial statements.

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	Feb. 18, 2020	Feb. 20, 2019	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.31	$ 0.31	$ 0.31	$ 0.31

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ (18.8)	$ 91.2
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Amortization and depreciation	5	6.7
Share-based payments expense	2.9	4.6
Deferred income tax (benefit) provision, net	(19.8)	5.3
Net realized investment loss (gains)	36.1	(52.5)
Undistributed earnings from alternative investment portfolio	(2.5)	(1.9)
Loss on disposals of long-lived assets, net	0.2	0
Change in:
Accrued investment income	2.5	(0.3)
Receivables	217.6	1.8
Deferred acquisition costs	1.1	(0.5)
Ceded unearned premiums	(111.5)	(104.9)
Reserves for losses and loss adjustment expenses	(78.8)	15.2
Unearned premiums	59.2	43.9
Ceded reinsurance payable and funds held	(96)	75.8
Income taxes	16.3	3.2
Accrued underwriting expenses and other liabilities	(30.2)	6.7
Other, net	(14.7)	(38.7)
Cash (used in) provided by operating activities	(31.4)	55.6
Cash flows from investing activities:
Sales of fixed maturity investments	594.1	235.5
Maturities and mandatory calls of fixed maturity investments	158.2	65.8
Sales of equity securities	24.8	15
Sales of other investments	19.2	22
Purchases of fixed maturity investments	(831.1)	(358.9)
Purchases of equity securities	(12.2)	(12.1)
Purchases of other investments	(5.9)	(13.2)
Change in foreign regulatory deposits and voluntary pools	3.9	(0.3)
Change in short-term investments	112.3	38.3
Settlements of foreign currency exchange forward contracts	3.1	3.6
Purchases of fixed assets	(2.3)	(7.3)
Other, net	(2.8)	(20.1)
Cash provided by (used in) investing activities	61.3	(31.7)
Cash flows from financing activities:
Activity under stock incentive plans	0.3	0.3
Payment of cash dividends to common shareholders	(10.7)	(10.8)
Cash used in financing activities	(10.4)	(10.5)
Effect of exchange rate changes on cash	1.4	0.1
Change in cash	20.9	13.5
Cash, beginning of year	137.8	139.2
Cash, end of period	$ 158.7	$ 152.7

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of Argo Group International Holdings, Ltd. (“Argo Group,” “we” or the “Company”) and its subsidiaries have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance and reinsurance products in the property and casualty market. The preparation of interim financial statements in conformity with 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 reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our consolidated financial statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; estimates of written and earned premiums; reinsurance premium receivable; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of goodwill and intangibles and our deferred tax asset valuation allowance. Actual results could differ from those estimates. Certain financial information that normally is included in annual financial statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the Securities and Exchange Commission ("SEC") on February 28, 2020. The interim financial information as of, and for the three months ended, March 31, 2020 and 2019 is unaudited. However, in the opinion of management, the interim information includes all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the results presented for the interim periods. The operating results for the interim periods are not necessarily indicative of the results to be expected for the full year. All significant intercompany amounts have been eliminated in consolidation. Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation. During the first quarters of 2020 and 2019, we incurred non-recurring costs associated with a number of activities that began with proxy solicitation efforts and shareholder engagement. For the three months ended March 31, 2019, these costs were $0.5 million and were previously included in the line item "Underwriting, Acquisition and Insurance Expenses" in the Consolidated Statements of Income in our Quarterly Report on Form 10-Q for the three-month period ended March 31, 2019. To conform to the current year's presentation, these amounts have been reclassified out of "Underwriting, Acquisition and Insurance Expenses" and into "Other Corporate Expenses" in the Consolidated Statements of (Loss) Income herein. Please see Note 12, "Underwriting, Acquisition and Insurance Expenses & Other Corporate Expenses" for further discussion. Risks and Uncertainties Certain risks and uncertainties are inherent to our day-to-day operations. Adverse changes in the economy could lower demand for our insurance products or negatively impact our investment results, both of which could have an adverse effect on the revenue and profitability of our operations. The global COVID-19 pandemic has resulted in and is expected to continue to result in significant disruptions in economic activity and financial markets. The cumulative effects of COVID-19 on the Company, and the effect of any other public health outbreak, cannot be predicted at this time, but could reduce demand for our insurance policies, result in increased level of losses, settlement expenses or other operating costs, reduce the market value of invested assets held by the Company or negatively impact the fair value of our goodwill.

Recently Adopted Accounting Pro

Recently Adopted Accounting Pronouncements	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements & Updates to Accounting Policies Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-13, “Measurement of Credit Losses on Financial Instruments” (Topic 326), commonly referred to as current expected credit losses or "CECL." ASU 2016-13 requires organizations to estimate credit losses on certain types of financial instruments, including receivables and available-for-sale debt securities, by introducing an approach based on expected losses. The expected loss approach will require entities to incorporate considerations of historical information, current information and reasonable and supportable forecasts. The updated guidance also amends the previous other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within the year of adoption. The guidance requires a modified retrospective transition method. We adopted the updated guidance effective January 1, 2020 using the modified retrospective approach, which resulted in a $7.9 million net of tax reduction to retained earnings. Partially offsetting this reduction of retained earnings was a $5.7 million net of tax increase in other comprehensive income representing the reclassification of unrealized investment losses to credit losses under this accounting update. The cumulative effect adjustment decreased shareholders’ equity $2.2 million. In January 2020, the FASB issued ASU 2020-01, "Investments — Equity Securities" (Topic 321), "Investments — Equity Method and Joint Ventures" (Topic 323), and "Derivatives and Hedging" (Topic 815). ASU 2020-01 clarifies that entities that apply the measurement alternative in ASC 321 should consider observable transactions that result in entities initially applying or discontinuing the use of the equity method of accounting under ASC 323. The guidance also says that certain forward contracts and purchased options on equity securities that are not deemed to be in-substance common stock under ASC 323 or accounted for as derivatives under ASC 815 are in the scope of ASC 321. The guidance is effective for public business entities ("PBEs") for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years, with early adoption is permitted. The guidance should be applied prospectively. We are currently in the process of evaluating the impact that the adoption of the ASU will have on our financial results and disclosures, but it is not expected to have a material impact upon adoption. In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform" (Topic 848). ASU 2020-04 provides temporary optional expedients and exceptions to the US GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens of the expected market transition from the London Interbank Offered Rate (LIBOR) and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate. Entities can elect not to apply certain modification accounting requirements to contracts affected by what the guidance calls reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Entities can elect various optional expedients for hedging relationships affected by reference rate reform, if certain criteria are met. The guidance is effective upon issuance and generally can be applied through December 31, 2022. We have certain debt agreements for which the interest rate is based on LIBOR rates. We are currently investigating the impacts of the transition from LIBOR to other rates on these contracts and the resulting accounting requirements, but do not expect the change in rates to have a material impact on our financial statements. Updates to Accounting Policies The following accounting policies have been updated to reflect the adoption of ASU 2016-13, as described above. Investment Impairments of Available for Sale Fixed Maturities We regularly review our investments to identify and evaluate those that may have credit impairments. For fixed maturity securities, the evaluation for credit losses is generally based on the present value of expected cash flows of the security as compared to the amortized book value, the financial condition, near-term and long-term prospects for the issuer, including industry conditions, implications of rating agency actions, the likelihood of principal and interest recoverability and whether it is more likely than not we will be required to sell the investment prior to the anticipated recovery in value. Effective January 1, 2020 with the adoption of ASU 2016-13 Financial Instruments-Credit Losses, we recognize credit losses on fixed maturities through an allowance account. For fixed maturities that we do not intend to sell or for which it is more likely than not we will not be required to sell prior to the anticipated recovery in value, we separate the credit component of the impairment from the component related to all other market factors and report the credit loss component to net realized investment gains (losses) in the Consolidated Statement of Income. The impairment related to all other market factors is reported as a separate component of shareholder’s equity in other comprehensive income (loss). The credit loss allowance account is adjusted for any additional credit losses or subsequent recoveries and the cost basis of the fixed maturity security is not adjusted. For fixed maturity securities that we intend to sell or for which it is more likely that not that we will be required to sell before an anticipated recovery in value, the full amount of the impairment is recognized in net realized investment gains (losses) in the Consolidated Statement of Income and the cost basis of the fixed maturity security is adjusted to reflect the recognized realized loss. The new cost basis is not adjusted for any recoveries in fair value. We report accrued investment income separately from fixed maturity securities and have elected to not measure an allowance for credit losses for accrued investment income. The write-off of investment income accrued for fixed maturities that have defaulted on interest payments is recognized as a loss in net realized investment gains (losses), in the period of the default, in the Consolidated Statement of Income. Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. We report our reinsurance recoverables net of an allowance for estimated uncollectible reinsurance. The allowance is based upon our ongoing review of amounts outstanding, length of collection periods, changes in reinsurer credit standing, disputes, applicable coverage defenses and other relevant factors. We use the rating-based method to estimate the uncollectible reinsurance reserves due to credit losses. Under this method, reinsurance credit risk is estimated by considering the reinsurers probability of default. Reinsurance recoverables are forecasted out of the assumed billing periods and a liquidation factor is applied based on the rating of the reinsurer and adjusted as needed based on our historical experience with the reinsurers. Additionally, reinsurance receivable balances are evaluated to identify any dispute risk and when required, an additional reserve is recorded. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as any subsequent collections of amounts previously written off, are reported as part of underwriting expense. We evaluate and monitor the financial condition of its reinsurers under voluntary reinsurance arrangements to minimize its exposure to significant losses from reinsurer insolvencies. Premiums and Unearned Premium Reserves Premiums are recognized as revenues pro rata over the policy period. Unearned premium reserves represent the unexpired portion of policy premiums. Accrued retrospective premiums are included in premium balances receivable. Premiums receivable balances are reported net of an allowance for expected losses, both dispute and credit related. The allowance is based upon our ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. Credit risk is partially mitigated by our ability to cancel the policy if the policyholder does not pay the premium.

Investments

Investments	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments	InvestmentsIncluded in “Total investments” in our Consolidated Balance Sheets at March 31, 2020 and December 31, 2019 is $120.9 million and $158.6 million, respectively, of assets managed on behalf of the trade capital providers, who are third-party participants that provide underwriting capital to the operations of Syndicates 1200 and 1910. Fixed Maturities The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: March 31, 2020 (in millions) Amortized Gross Gross Allowance for Credit Losses (1) Fair Fixed maturities U.S. Governments $ 320.2 $ 18.5 $ — $ — $ 338.7 Foreign Governments 245.9 4.6 10.4 0.4 239.7 Obligations of states and political subdivisions 143.8 5.4 0.7 — 148.5 Corporate bonds 1,705.4 17.8 98.3 31.1 1,593.8 Commercial mortgage-backed securities 242.9 2.4 3.5 — 241.8 Residential mortgage-backed securities 534.0 18.8 6.4 — 546.4 Asset-backed securities 166.9 1.1 6.2 0.1 161.7 Collateralized loan obligations 275.3 0.4 22.8 — 252.9 Total fixed maturities $ 3,634.4 $ 69.0 $ 148.3 $ 31.6 $ 3,523.5 (1) Effective January 1, 2020 we adopted ASC-326 and as a result any credit impairment losses on our available-for-sale fixed maturities are recorded as an allowance, subject to reversal. Prior periods have not been restated to conform with the current year presentation. See Note 1. December 31, 2019 (in millions) Amortized Gross Gross Fair Fixed maturities U.S. Governments $ 353.5 $ 2.3 $ 1.2 $ 354.6 Foreign Governments 244.8 4.6 0.7 248.7 Obligations of states and political subdivisions 145.8 6.9 0.1 152.6 Corporate bonds 1,777.4 37.7 34.7 1,780.4 Commercial mortgage-backed securities 213.5 4.6 1.1 217.0 Residential mortgage-backed securities 479.1 10.4 0.6 488.9 Asset-backed securities 164.2 1.5 0.2 165.5 Collateralized loan obligations 226.7 0.5 1.4 225.8 Total fixed maturities $ 3,605.0 $ 68.5 $ 40.0 $ 3,633.5 Contractual Maturity The amortized cost and fair values of fixed maturity investments as of March 31, 2020, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 306.6 $ 301.6 Due after one year through five years 1,489.7 1,419.3 Due after five years through ten years 554.2 536.8 Thereafter 64.8 63.0 Structured securities 1,219.1 1,202.8 Total $ 3,634.4 $ 3,523.5 The expected maturities may differ from the contractual maturities because debtors may have the right to call or prepay obligations. Other Investments Details regarding the carrying value and unfunded investment commitments of other investments as of March 31, 2020 and December 31, 2019 were as follows: March 31, 2020 (in millions) Carrying Unfunded Investment Type Hedge funds $ 105.7 $ — Private equity 220.1 104.6 Overseas deposits 92.3 — Other 4.3 — Total other investments $ 422.4 $ 104.6 December 31, 2019 (in millions) Carrying Unfunded Investment Type Hedge funds $ 109.5 $ — Private equity 268.1 110.0 Overseas deposits 114.6 — Other 4.3 — Total other investments $ 496.5 $ 110.0 The following describes each investment type: • Hedge funds: Hedge funds include funds that primarily buy and sell stocks, including short sales, multi-strategy credit, relative value credit and distressed credit. • Private equity: Private equity includes buyout funds, real asset/infrastructure funds, credit special situations funds, mezzanine lending funds and direct investments and strategic non-controlling minority investments in private companies that are principally accounted for using the equity method of accounting. • Overseas deposits: Overseas deposits are principally invested in short-term sovereign fixed income and investment grade corporate securities and international stocks. • Other: Other includes participation in investment pools. Unrealized Losses and Other-Than-Temporary Impairments An aging of unrealized losses on our investments in fixed maturities is presented below: March 31, 2020 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments (1) $ 1.4 $ — $ — $ — $ 1.4 $ — Foreign Governments 143.6 10.4 — — 143.6 10.4 Obligations of states and political subdivisions 24.2 0.7 — — 24.2 0.7 Corporate bonds 850.3 75.7 29.7 22.6 880.0 98.3 Commercial mortgage-backed securities 132.6 3.5 — — 132.6 3.5 Residential mortgage-backed securities 101.1 5.5 8.9 0.9 110.0 6.4 Asset-backed securities 103.3 5.8 4.7 0.4 108.0 6.2 Collateralized loan obligations 194.9 19.0 54.9 3.8 249.8 22.8 Total fixed maturities $ 1,551.4 $ 120.6 $ 98.2 $ 27.7 $ 1,649.6 $ 148.3 (1) Unrealized losses are less than $0.1 million. December 31, 2019 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 114.6 $ 1.1 $ 17.0 $ 0.1 $ 131.6 $ 1.2 Foreign Governments (1) 117.6 0.7 5.1 — 122.7 0.7 Obligations of states and political subdivisions (1) 0.7 — 2.1 0.1 2.8 0.1 Corporate bonds 249.4 18.9 63.6 15.8 313.0 34.7 Commercial mortgage-backed securities (1) 74.8 1.1 4.9 — 79.7 1.1 Residential mortgage-backed securities 66.9 0.3 25.2 0.3 92.1 0.6 Asset-backed securities 22.5 0.1 18.9 0.1 41.4 0.2 Collateralized loan obligations 54.7 0.8 116.7 0.6 171.4 1.4 Total fixed maturities $ 701.2 $ 23.0 $ 253.5 $ 17.0 $ 954.7 $ 40.0 (1) Unrealized losses are less than $0.1 million. We hold a total of 4,842 fixed income securities, of which 2,480 were in an unrealized loss position for less than one year and 194 were in an unrealized loss position for a period one year or greater as of March 31, 2020. Following the adoption of ASC 326, as described in Note 1, beginning January 1, 2020 we complete a detailed analysis each quarter to assess whether the decline in the fair value of a fixed maturity security below its amortized cost basis is the result of a credit loss. All available-for-sale securities with unrealized losses are reviewed. We consider many factors in completing this detailed analysis to determine where a credit loss exists, including the extent to which fair value is below cost, the implied yield to maturity, rating downgrades of the security and whether or not the issuer has failed to make scheduled principal or interest payments. We also take into consideration information about the financial condition of the issuer and industry factors that could negatively impact the capital markets If the decline in fair value of an available-for-sale fixed maturity security below its amortized cost is considered to be the result of a credit loss, we compare the estimated present value of the cash flows expected to be collected to the amortized cost of the security. The extent to which the estimated present value of the cash flows expected to be collected is less than the amortized cost of the security represents the credit loss, which is recorded as an allowance and recognized in net realized gains (losses) in the Statement of (Loss) Income. The allowance is limited to the difference between the fair value and the amortized cost of the security. Any remaining decline in fair value represents the non-credit portion of the impairment, which is recognized in other comprehensive income. We also consider whether we intend to sell an available-for-sale security or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in net realized gains (losses) in the Statement of Income based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security. The following table presents a reconciliation of the beginning and ending balances for the allowance for credit losses on available-for-sale fixed maturity securities: For the Three Months Ended (in millions) 2020 Beginning balance, January 1, 2020 $ — Additions related to initial adoption of accounting standard 6.9 Provision for expected credit losses 24.7 Reductions due to sales/defaults of credit-impaired securities — Ending balance, March 31, 2020 $ 31.6 Total credit impairment charges included in net realized investment gains (losses) in the Consolidated Statement of (Loss) Income was $24.7 million for the three months ended March 31, 2020. Total other-than-temporary impairment charges included in net realized investments (gains) losses was $4.3 million for the three months ended March 31, 2019. Net Realized Investment Gains and Losses The following table presents our gross realized investment gains (losses): For the Three Months Ended (in millions) 2020 2019 Realized gains on fixed maturities and other Fixed maturities $ 20.8 $ 3.6 Other investments 48.2 8.8 69.0 12.4 Realized losses on fixed maturities and other Fixed maturities (7.7) (2.4) Other investments (31.8) (8.1) Credit losses on fixed maturities (24.7) (4.3) (64.2) (14.8) Equity securities Net realized (losses) gains on equity securities (1.6) 0.7 Change in unrealized (losses) gains on equity securities held at the end of the period (39.3) 54.2 Net realized (losses) gains on equity securities (40.9) 54.9 Net realized investment (losses) gains before income taxes (36.1) 52.5 Income tax benefit (provision) 8.0 (9.7) Net realized investment (losses) gains net of income taxes $ (28.1) $ 42.8 The cost of securities sold is based on the specific identification method. Changes in unrealized (losses) gains related to investments are summarized as follows: For the Three Months Ended (in millions) 2020 2019 Change in unrealized (losses) gains Fixed maturities $ (111.8) $ 59.9 Other investments (14.2) — Other and short-term investments (0.2) — Net unrealized investment (losses) gains before income taxes (126.2) 59.9 Income tax benefit (provision) 19.2 (9.6) Net unrealized investment (losses) gains, net of income taxes $ (107.0) $ 50.3 Foreign Currency Exchange Forward Contracts We entered into foreign currency exchange forward contracts to manage operational currency exposure on our Canadian dollar investment portfolio and certain catastrophic events, minimize negative impacts to investment portfolio returns, and gain exposure to a total return strategy which invests in multiple currencies. The currency forward contracts are carried at fair value in our Consolidated Balance Sheets in “Other assets.” The net gains are included in “Net realized investment (losses) gains” in our Consolidated Statements of (Loss) Income. The fair value of our foreign currency exchange forward contracts as of March 31, 2020 and December 31, 2019 was as follows: (in millions) March 31, 2020 December 31, 2019 Operational currency exposure $ 7.0 $ (0.8) Asset manager investment exposure 0.2 (0.3) Total return strategy (2.3) 2.2 Total $ 4.9 $ 1.1 The following table represents our gross investment realized gains and losses on our foreign currency exchange forward contracts: For the Three Months Ended (in millions) 2020 2019 Realized gains Operational currency exposure $ 5.4 $ 0.3 Asset manager investment exposure 0.8 1.1 Total return strategy 25.0 6.3 Gross realized investment gains 31.2 7.7 Realized losses Operational currency exposure (1.7) (2.1) Asset manager investment exposure (0.4) (0.2) Total return strategy (28.0) (4.7) Gross realized investment losses (30.1) (7.0) Net realized investment gains on foreign currency exchange forward contracts $ 1.1 $ 0.7 Regulatory Deposits, Pledged Securities and Letters of Credit We are required to maintain assets on deposit with various regulatory authorities to support our insurance and reinsurance operations. We maintain assets pledged as collateral in support of irrevocable letters of credit issued under the terms of certain reinsurance agreements for reported loss and loss expense reserves. The following table presents our components of restricted assets: (in millions) March 31, 2020 December 31, 2019 Securities on deposit for regulatory and other purposes $ 228.3 $ 192.5 Securities pledged as collateral for letters of credit and other 170.8 169.9 Securities and cash on deposit supporting Lloyd’s business 400.7 412.8 Total restricted investments $ 799.8 $ 775.2 Fair Value Measurements Fair value is 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. Fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market. Market participants are buyers and sellers in the principal (or most advantageous) market that are independent, knowledgeable, able to transact for the asset or liability and willing to transfer the asset or liability. Valuation techniques consistent with the market approach, income approach and/or cost approach are used to measure fair value. The inputs of these valuation techniques are categorized into three levels. • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the reporting date. We define actively traded as a security that has traded in the past seven days. We receive one quote per instrument for Level 1 inputs. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. We receive one quote per instrument for Level 2 inputs. • Level 3 inputs are unobservable inputs. Unobservable inputs reflect our own judgments about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. We receive fair value prices from third-party pricing services and our outside investment managers. These prices are determined using observable market information such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2020 and December 31, 2019. A description of the valuation techniques we use to measure assets at fair value is as follows: Fixed Maturities (Available-for-Sale) Levels 1 and 2: • United States Treasury securities are typically valued using Level 1 inputs. For these securities, we obtain fair value measurements from third-party pricing services using quoted prices (unadjusted) in active markets at the reporting date. • United States Government agencies, non-U.S. Government securities, obligations of states and political subdivisions, credit securities and foreign denominated government and credit securities are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, yield curves, live trading levels, trade execution data, credit information and the security’s terms and conditions, among other things. • Asset and mortgage-backed securities and collateralized loan obligations are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. Fixed Maturities (Available-for-Sale) Levels 3: We own term loans that are valued using unobservable inputs. Equity Securities Level 1: Equity securities are principally reported at fair value using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Equity Securities Level 3: We own certain equity securities that are reported at fair value using Level 3 inputs. The valuation techniques for these securities include the following: • Fair value measurements for an investment in an equity fund obtained by applying final prices provided by the administrator of the fund, which is based upon certain estimates and assumptions. • Fair value measurements from a broker and an independent valuation service, both based upon estimates and assumptions. Other Investments Level 2: Foreign regulatory deposits are assets held in trust in jurisdictions where there is a legal and regulatory requirement to maintain funds locally in order to protect policyholders. Lloyd’s is the appointed investment manager for the funds. These assets are invested in short-term government securities, agency securities and corporate bonds and are valued using Level 2 inputs based upon values obtained from Lloyd’s. Short-term Investments: Short-term investments are principally reported at fair value using Level 1 inputs, with the exception of short-term corporate and governmental bonds reported at fair value using Level 2 inputs as described in the fixed maturities section above. Values for the investments categorized as Level 1 are obtained from various financial institutions as of the reporting date. Based on an analysis of the inputs, our financial assets measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 338.7 $ 336.6 $ 2.1 $ — Foreign Governments 239.7 — 239.7 — Obligations of states and political subdivisions 148.5 — 148.5 — Corporate bonds 1,593.8 — 1,586.4 7.4 Commercial mortgage-backed securities 241.8 — 241.8 — Residential mortgage-backed securities 546.4 — 546.4 — Asset-backed securities 161.7 — 161.7 — Collateralized loan obligations 252.9 — 252.9 — Total fixed maturities 3,523.5 336.6 3,179.5 7.4 Equity securities 132.9 127.2 — 5.7 Other investments 92.3 — 92.3 — Short-term investments 732.6 708.3 24.3 — $ 4,481.3 $ 1,172.1 $ 3,296.1 $ 13.1 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 354.6 $ 349.1 $ 5.5 $ — Foreign Governments 248.7 — 248.7 — Obligations of states and political subdivisions 152.6 — 152.6 — Corporate bonds 1,780.4 — 1,773.0 7.4 Commercial mortgage-backed securities 217.0 — 217.0 — Residential mortgage-backed securities 488.9 — 488.9 — Asset-backed securities 165.5 — 165.5 — Collateralized loan obligations 225.8 — 225.8 — Total fixed maturities 3,633.5 349.1 3,277.0 7.4 Equity securities 124.4 117.8 — 6.6 Other investments 400.2 — 400.2 — Short-term investments 845.0 823.5 21.5 — $ 5,003.1 $ 1,290.4 $ 3,698.7 $ 14.0 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs The fair value measurements in the tables above do not equal “Total investments” on our Consolidated Balance Sheets as they exclude certain other investments that are accounted for under the equity-method of accounting. A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Observable Inputs (Level 3) (in millions) Credit Financial Equity Total Beginning balance, January 1, 2020 $ 7.4 $ 6.6 $ 14.0 Transfers into Level 3 — — — Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — (0.9) (0.9) Purchases, issuances, sales, and settlements: Purchases — — — Issuances — — — Sales — — — Settlements — — — Ending balance, March 31, 2020 $ 7.4 $ 5.7 $ 13.1 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at March 31, 2020 $ — $ — $ — (in millions) Credit Financial Equity Total Beginning balance, January 1, 2019 $ 2.2 $ 8.2 $ 10.4 Transfers into Level 3 3.5 — 3.5 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income (0.4) (1.6) (2.0) Included in other comprehensive loss 0.6 — 0.6 Purchases, issuances, sales, and settlements: Purchases 1.9 — 1.9 Issuances — — — Sales (0.4) — (0.4) Settlements — — — Ending balance, December 31, 2019 $ 7.4 $ 6.6 $ 14.0 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2019 $ — $ — $ — At March 31, 2020 and December 31, 2019, we did not have any financial assets or financial liabilities measured at fair value on a nonrecurring basis or any financial liabilities on a recurring basis.

Allowance for Credit Losses

Allowance for Credit Losses	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Allowance for Credit Losses	Allowance for Credit Losses Premiums receivable The following table represents the balances of premiums receivable, net of allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months ended March 31, 2020. (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Balance, January 1, 2020 $ 688.2 $ 7.9 Cumulative effect of adoption of ASU 2016-13 at January 1, 2020 — Current period change for estimated uncollectible premiums 0.8 Write-offs of uncollectible premiums receivable — Balance, March 31, 2020 $ 739.1 $ 8.7 Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2020 and January 1, 2020, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2020. (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2020 $ 3,104.6 $ 1.1 Cumulative effect of adoption of ASU 2016-13 at January 1, 2020 2.5 Current period change for estimated uncollectible reinsurance — Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2020 $ 2,820.9 $ 3.6

Reserves for Losses and Loss Ad

Reserves for Losses and Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	Reserves for Losses and Loss Adjustment Expenses The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): For the Three Months Ended (in millions) 2020 2019 Net reserves beginning of the year $ 2,722.7 $ 2,562.9 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 278.2 240.4 Prior accident years 2.7 (2.5) Losses and LAE incurred during calendar year, net of reinsurance 280.9 237.9 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 72.6 34.7 Prior accident years 263.8 221.0 Losses and LAE payments made during current calendar year, net of reinsurance: 336.4 255.7 Change in participation interest (1) 32.5 (14.6) Foreign exchange adjustments (25.6) (9.1) Net reserves - end of period 2,674.1 2,521.4 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,393.5 2,147.5 Gross reserves - end of period $ 5,067.6 $ 4,668.9 (1) Amount represents the change in reserves due to changing our participation in Syndicates 1200 and 1910. Reserves for losses and LAE represent the estimated indemnity cost and related adjustment expenses necessary to investigate and settle claims. Such estimates are based upon individual case estimates for reported claims, estimates from ceding companies for reinsurance assumed and actuarial estimates for losses that have been incurred but not yet reported to the insurer. Any change in probable ultimate liabilities is reflected in current operating results. Underwriting results for the three months ended March 31, 2020 included $26.2 million of net losses and loss adjustment expenses attributed to the COVID-19 pandemic, primarily resulting from contingency and property exposures in the company’s International Operations and property exposures in its U.S. Operations. Property losses relate to sub-limited affirmative business interruption coverage, primarily in certain International markets, as well as expected costs associated with claims handling. The impact from the unfavorable (favorable) development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: For the Three Months Ended (in millions) 2020 2019 U.S. Operations $ 3.3 $ (4.0) International Operations (0.4) 0.8 Run-off Lines (0.2) 0.7 Total unfavorable (favorable) prior-year development $ 2.7 $ (2.5) The following describes the primary factors behind each segment’s prior accident year reserve development for the three months ended March 31, 2020 and 2019: Three months ended March 31, 2020: • U.S. Operations: Unfavorable development in professional lines and liability, partially offset by favorable development in specialty related to our surety business unit. • International Operations: Favorable development in property and assumed reinsurance largely offset by unfavorable development in professional lines. • Run-off Lines: Favorable development in risk management workers compensation, partially offset by unfavorable development in other run-off lines. Three months ended March 31, 2019: • U.S. Operations: Favorable development in liability and specialty lines, partially offset by unfavorable development in workers compensation and commercial multi-peril lines. • International Operations: Unfavorable development in general liability, partially offset by unfavorable movements in property re insurance . • Run-off Lines: Unfavorable development in other run-off lines. In the opinion of management, our reserves represent the best estimate of our ultimate liabilities, based on currently known facts, current law, current technology and assumptions considered reasonable where facts are not known. Due to the significant uncertainties and related management judgments, there can be no assurance that future favorable or unfavorable loss development, which may be material, will not occur. The spread of COVID-19 and related economic shutdown has increased the uncertainty that is always present in our estimate of the ultimate cost of loss and settlement expense. Actuarial models base future emergence on historic experience, with adjustments for current trends, and the appropriateness of these assumptions involved more uncertainty as of March 31, 2020. We expect there will be impacts to the timing of loss emergence and ultimate loss ratios for certain coverages we underwrite. The industry is experiencing new issues, including the temporary suspension of civil court cases in most states, the extension of certain statutes of limitations and the impact on our insureds from a significant reduction in economic activity. Our booked reserves include consideration of these factors, but legislative, regulatory or judicial actions could result in loss reserve deficiencies and reduce earnings in future periods.

Disclosures about Fair Value of

Disclosures about Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Disclosures about Fair Value of Financial Instruments	Disclosures about Fair Value of Financial Instruments Cash. The carrying amount approximates fair value. Investment securities and short-term investments. See Note 3, “Investments,” for additional information. Premiums receivable and reinsurance recoverables on paid losses. The carrying value of current receivables and reinsurance recoverables on paid losses approximates fair value. Debt. At March 31, 2020 and December 31, 2019, the fair value of our debt instruments is determined using both Level 1 and Level 2 inputs, as previously defined in Note 3, "Investments". We receive fair value prices from third-party pricing services for our financial instruments as well as for similar financial instruments. These prices are determined using observable market information such as publicly traded quoted prices, and trading prices for similar financial instruments actively being traded in the current market. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2020 and December 31, 2019. A description of the valuation techniques we use to measure these liabilities at fair value is as follows: Senior Unsecured Fixed Rate Notes Level 1: • Our senior unsecured fixed rate notes are valued using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Junior Subordinated Debentures and Floating Rate Loan Stock Level 2: • Our trust preferred debentures, subordinated debentures and floating rate loan stock are typically valued using Level 2 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices for similar securities being traded in active markets at the reporting date, as our specific debt instruments are more infrequently traded. A summary of our financial instruments whose carrying value did not equal fair value is shown below: March 31, 2020 December 31, 2019 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 172.7 $ 173.6 $ 172.7 $ 174.0 Subordinated debentures 84.8 92.3 84.7 92.5 Total junior subordinated debentures 257.5 265.9 257.4 266.5 Senior unsecured fixed rate notes 140.0 125.9 140.0 144.2 Floating rate loan stock 55.0 55.3 56.3 56.8 Based on an analysis of the inputs, our financial instruments measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, 2020 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 173.6 $ — $ 173.6 $ — Subordinated debentures 92.3 — 92.3 — Total junior subordinated debentures 265.9 — 265.9 — Senior unsecured fixed rate notes 125.9 125.9 — — Floating rate loan stock 55.3 — 55.3 — 447.1 125.9 321.2 — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2019 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 174.0 $ — $ 174.0 $ — Subordinated debentures 92.5 — 92.5 — Total junior subordinated debentures 266.5 — 266.5 — Senior unsecured fixed rate notes 144.2 144.2 — — Floating rate loan stock 56.8 — 56.8 — 467.5 144.2 323.3 — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity On February 18, 2020, our Board of Directors declared a quarterly cash dividend in the amount of $0.31 on each share of common stock outstanding. On March 16, 2020, we paid $10.7 million to our shareholders of record on March 2, 2020. On February 20, 2019, our Board of Directors declared a quarterly cash dividend in the amount of $0.31 on each share of common stock outstanding. On March 15, 2019, we paid $10.8 million to our shareholders of record on March 1, 2019. On May 3, 2016, our Board of Directors authorized the repurchase of up to $150.0 million of our common shares (“2016 Repurchase Authorization”). The 2016 Repurchase Authorization supersedes all previous repurchase authorizations. As of March 31, 2020, availability under the 2016 Repurchase Authorization for future repurchases of our common shares was $53.3 million. We did not repurchase any common shares for the three months ended March 31, 2020.

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive (Loss) Income	Accumulated Other Comprehensive (Loss) Income A summary of changes in accumulated other comprehensive (loss) income, net of taxes (where applicable) by component for the three months ended March 31, 2020, and 2019 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2020 $ (22.6) $ 33.5 $ (8.1) $ 2.8 Other comprehensive loss before reclassifications (3.4) (101.7) — (105.1) Amounts reclassified from accumulated other comprehensive loss — (5.3) — (5.3) Net current-period other comprehensive loss (3.4) (107.0) — (110.4) Cumulative effect of adoption of ASU 2016-13 — 5.7 — 5.7 Balance at March 31, 2020 $ (26.0) $ (67.8) $ (8.1) $ (101.9) (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2019 $ (22.4) $ (49.0) $ (6.7) $ (78.1) Other comprehensive income before reclassifications 0.2 47.7 — 47.9 Amounts reclassified from accumulated other comprehensive income — 2.6 — 2.6 Net current-period other comprehensive income 0.2 50.3 — 50.5 Balance at March 31, 2019 $ (22.2) $ 1.3 $ (6.7) $ (27.6) The amounts reclassified from accumulated other comprehensive (loss) income shown in the above table have been included in the following captions in our Consolidated Statements of (Loss) Income: For the Three Months Ended (in millions) 2020 2019 Unrealized gains and losses on securities: Net realized investment (gains) loss $ (3.4) $ 3.1 Benefit for income taxes (1.9) (0.5) Net of taxes $ (5.3) $ 2.6

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net (Loss) Income Per Common Share	Net (Loss) Income Per Common Share The following table presents the calculation of net (loss) income per common share on a basic and diluted basis: For the Three Months Ended (in millions, except number of shares and per share amounts) 2020 2019 Net (loss) income $ (18.8) $ 91.2 Weighted average common shares outstanding - basic 34,469,516 33,984,329 Effect of dilutive securities: Equity compensation awards — 753,610 Weighted average common shares outstanding - diluted 34,469,516 34,737,939 Net (loss) income per common share: Basic $ (0.55) $ 2.68 Diluted $ (0.55) $ 2.63 Excluded from the weighted average common shares outstanding calculation at March 31, 2020 and 2019 are 11,315,889 shares, which are held as treasury shares. The shares are excluded as of their repurchase date. For the three months ended March 31, 2020, 294,869 shares were not included in the calculation of diluted net income per common share as these instruments were anti-dilutive. For the three months ended March 31, 2019, there were no anti-dilutive shares of common stock to be excluded from the computation of diluted net income per common share.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Interest paid and income taxes paid (recovered) were as follows: For the Three Months Ended (in millions) 2020 2019 Senior unsecured fixed rate notes $ 2.3 $ 2.3 Junior subordinated debentures 3.7 4.1 Other indebtedness 1.9 2.4 Total interest paid $ 7.9 $ 8.8 Income taxes paid 0.3 0.2 Income taxes recovered — — Income taxes paid, net $ 0.3 $ 0.2

Share-based Compensation

Share-based Compensation	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Share-based Compensation	Share-based Compensation Argo Group’s 2019 Omnibus Incentive Plan In May 2019, our shareholders approved the 2019 Omnibus Incentive Plan (the “2019 Plan”), which provides equity-based and cash-based performance-related incentives to key employees, non-employee directors and other service providers. The intent of the 2019 Plan is to encourage and provide for the acquisition of an ownership interest in Argo Group, enabling us to attract and retain qualified and competent persons to serve as members of our management team and the Board of Directors. The 2019 Plan authorizes 1,885,000 shares of common stock to be granted as equity-based awards. No further grants will be made under any prior plan; however, any awards under a prior plan that are outstanding as of the effective date shall remain subject to the terms and conditions of, and be governed by, such prior plan. Awards granted under the 2019 Plan may be in the form of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards, other stock-based awards or other cash-based awards. Awards may be granted either alone or in addition to or in tandem with other awards authorized under the 2019 Plan. Awards that are settled in stock will count as one share for the purposes of reducing the share reserve under the 2019 Plan. Shares issued under this plan may be shares that are authorized and unissued or shares that we reacquired, including shares purchased on the open market. Stock options and stock appreciation rights are required to have an exercise price that is not less than the fair market value on the date of grant. The term of these awards is not to exceed ten years. Restricted Shares A summary of restricted share activity as of March 31, 2020 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2020 471,271 $ 60.09 Vested and issued (134,983) $ 55.87 Expired or forfeited (45,482) $ 61.19 Outstanding at March 31, 2020 290,806 $ 61.94 The restricted shares vest over one Stock-Settled SARs A summary of stock-settled SARs activity as of March 31, 2020 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2020 625,368 $ 33.60 Exercised (369,362) $ 32.59 Expired or forfeited — $ — Outstanding at March 31, 2020 256,006 $ 35.05 As of March 31, 2020, all stock-settled SARs are fully vested. Upon exercise of the stock-settled SARs, the employee is entitled to receive shares of our common stock equal to the appreciation of the stock as compared to the exercise price. There was no expense recognized for the three months ending March 31, 2020 for stock-settled SARs. Expense recognized for the stock-settled SARs was $0.4 million for the three months ended March 31, 2019. As of March 31, 2020, there was no unrecognized compensation cost related to stock-settled SARs outstanding.

Underwriting, Acquisition and I

Underwriting, Acquisition and Insurance Expenses	3 Months Ended
	Mar. 31, 2020
Underwriting Acquisition And Insurance Expenses [Abstract]
Underwriting, Acquisition and Insurance Expenses	Underwriting, Acquisition and Insurance Expenses & Other Corporate Expenses Underwriting, Acquisition and Insurance Expenses Underwriting, acquisition and insurance expenses were as follows: For the Three Months Ended (in millions) 2020 2019 Commissions $ 65.3 $ 63.3 General expenses 98.9 88.6 Premium taxes, boards and bureaus 8.0 8.3 172.2 160.2 Net deferral of policy acquisition costs (4.2) — Total underwriting, acquisition and insurance expenses $ 168.0 $ 160.2 Other Corporate Expenses During the three months ended March 31, 2020 and 2019, we incurred costs of $3.3 million and $0.5 million, respectively, in connection with ongoing corporate governance and compensation matters, including responding to the 2019 subpoena from the SEC related to the Company's disclosure of certain compensation-related perquisites received by the Company's former CEO. These non-recurring costs are included in the line item “Other corporate expenses” in the Company’s Consolidated Statements of (Loss) Income, and have been excluded from the calculation of our expense ratio.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are incorporated under the laws of Bermuda and, under current Bermuda law, are not obligated to pay any taxes in Bermuda based upon income or capital gains. We have received an undertaking from the Supervisor of Insurance in Bermuda pursuant to the provisions of the Exempted Undertakings Tax Protection Act, 2011, which exempts us from any Bermuda taxes computed on profits, income or any capital asset, gain or appreciation or any tax in the nature of estate, duty or inheritance tax, at least until the year 2035. We do not consider ourselves to be engaged in a trade or business in the United States or the United Kingdom and, accordingly, do not expect to be subject to direct United States or United Kingdom income taxation. We have subsidiaries based in the United Kingdom that are subject to the tax laws of that country. Under current law, these subsidiaries are taxed at the applicable corporate tax rates. Certain of the United Kingdom subsidiaries are deemed to be engaged in business in the United States, and therefore, are subject to United States corporate tax in respect of a proportion of their United States underwriting business only. Relief is available against the United Kingdom tax liabilities in respect of overseas taxes paid that arise from the underwriting business. Our United Kingdom subsidiaries file separate United Kingdom income tax returns. We have subsidiaries based in the United States that are subject to United States tax laws. Under current law, these subsidiaries are taxed at the applicable corporate tax rates. Our United States subsidiaries generally file a consolidated United States federal income tax return. We also have operations in Belgium, Brazil, France, Ireland, Italy, Malta, Spain, and Switzerland, which also are subject to income taxes imposed by the jurisdiction in which they operate. We have operations in Barbados and the United Arab Emirates, which are not subject to income tax under the laws of those countries. Our expected income tax provision computed on pre-tax income (loss) at the weighted average tax rate has been calculated as the sum of the pre-tax income (loss) in each jurisdiction multiplied by that jurisdiction’s applicable statutory tax rate. For the three months ended March 31, 2020 and 2019, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: For the Three Months Ended March 31, 2020 2019 (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ (21.7) — % $ 32.0 — % United States (10.7) 55.0 % 69.4 14.4 % United Kingdom 1.7 183.2 % (3.5) 31.5 % Belgium — (1) 68.8 % — (1) 30.8 % Brazil 2.2 — % 1.8 — % United Arab Emirates 0.9 — % 0.2 — % Ireland — (1) — % — (1) — % Italy 3.4 — % (0.7) — % Malta 2.6 — % 0.9 — % Luxembourg — — % — — % Switzerland — (1) — % — (1) — % Pre-tax (loss) income $ (21.6) 12.8 % $ 100.1 8.9 % (1) Pre-tax income (loss) for the respective year was less than $0.1 million. Our effective tax rate may vary significantly from period to period depending on the jurisdiction generating the pre-tax income (loss) and its corresponding statutory tax rate. The geographic distribution of pre-tax income (loss) can fluctuate significantly between periods given the inherit nature of our business. A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate is as follows: For the Three Months Ended (in millions) 2020 2019 Income tax provision (benefit) at expected rate $ 0.8 $ 14.9 Tax effect of: Nontaxable investment income (0.1) (0.4) Foreign exchange adjustments (2.0) 0.5 Withholding taxes — (1) — (1) Prior period adjustments — (1) — Change in valuation allowance — (1) (0.6) Other (1.5) (5.5) Income tax (benefit) provision $ (2.8) $ 8.9 (1) Tax effect of the adjustment for the respective year was less than $0.1 million. Our gross deferred tax assets are supported by taxes paid in previous periods, reversal of taxable temporary differences and recognition of future taxable income. Management regularly evaluates the recoverability of the deferred tax assets and makes any necessary adjustments to them based upon any changes in management’s expectations of future taxable income. Realization of deferred tax assets is dependent upon our generation of future taxable income sufficient to recover tax benefits that cannot be recovered from taxes paid in the carryback period, generally for our US property and casualty insurers two years for net operating losses and for all our US subsidiaries three years for capital losses. If a company determines that any of its deferred tax assets will not result in future tax benefits, a valuation allowance must be established for the portion of these assets that are not expected to be realized. The net change in valuation allowance for deferred tax assets during 2020, which was negligible, related to the following: Internal Revenue Code Section 382 limited net operating loss carryforwards within the United States, cumulative losses incurred since inception, and valuation allowances acquired through or related to acquisitions. Based upon a review of our available evidence, both positive and negative discussed above, our management concluded that it is more-likely-than-not that the other deferred tax assets will be realized. For any uncertain tax positions not meeting the “more-likely-than-not” recognition threshold, accounting standards require recognition, measurement and disclosure in a company’s financial statements. We had no material unrecognized tax benefits as of March 31, 2020 and 2019. Our United States subsidiaries are no longer subject to U.S. federal and state income tax examinations by tax authorities for years before 2015. Our United Kingdom subsidiaries are no longer subject to United Kingdom income tax examinations by Her Majesty’s Revenue and Customs for years before 2016.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesArgo Group’s subsidiaries are parties to legal actions incidental to their business. Based on the opinion of legal counsel, management believes that the resolution of these matters will not materially affect our financial condition or results of operations.We have contractual commitments to invest up to $104.6 million related to our limited partnership investments at March 31, 2020. These commitments will be funded as required by the partnership agreements which can be called to be fulfilled at any time, not to exceed thirteen years

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Segment Information	Segment Information We are primarily engaged in underwriting property and casualty insurance and reinsurance. We have two ongoing reporting segments: U.S. Operations and International Operations. Additionally, we have a Run-off Lines segment for certain products that we no longer underwrite. We consider many factors, including the nature of each segment’s insurance and reinsurance products, production sources, distribution strategies and the regulatory environment, in determining how to aggregate reporting segments. Transactions between segments are reported in the segment that initiated the transaction. In evaluating the operating performance of our segments, we focus on core underwriting and investing results before the consideration of realized gains or losses from investments. Realized investment gains are reported as a component of the Corporate and Other segment, as decisions regarding the acquisition and disposal of securities reside with the corporate investment function and are not under the control of the individual business segments. Identifiable assets by segment are those assets used in the operation of each segment. Revenue and (loss) income before income taxes for each segment were as follows: For the Three Months Ended (in millions) 2020 2019 Revenue: Earned premiums U.S. Operations $ 302.5 $ 273.8 International Operations 132.3 146.7 Run-off Lines 0.2 — Total earned premiums 435.0 420.5 Net investment income U.S. Operations 25.2 23.1 International Operations 8.6 9.1 Run-off Lines 1.2 1.4 Corporate and Other 0.5 0.3 Total net investment income 35.5 33.9 Fee and other income 2.1 2.3 Net realized investment (losses) gains (36.1) 52.5 Total revenue $ 436.5 $ 509.2 For the Three Months Ended (in millions) 2020 2019 Income (loss) before income taxes U.S. Operations $ 36.9 $ 42.9 International Operations (12.3) 16.2 Run-off Lines 0.5 0.6 Total segment income before taxes 25.1 59.7 Corporate and Other (10.3) (10.9) Net realized investment and other (losses) gains (36.1) 52.5 Foreign currency exchange gains (loss) 3.0 (0.7) Other corporate expenses (3.3) (0.5) Total (loss) income before income taxes $ (21.6) $ 100.1 The table below presents earned premiums by geographic location for the three months ended March 31, 2020 and 2019. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. For the Three Months Ended (in millions) 2020 2019 United States $ 299.7 $ 272.6 United Kingdom 86.7 97.1 Bermuda 21.2 16.6 Malta 11.8 20.8 All other jurisdictions 15.6 13.4 Total earned premiums $ 435.0 $ 420.5 The following table represents identifiable assets: (in millions) March 31, 2020 December 31, 2019 U.S. Operations $ 5,656.8 $ 5,009.0 International Operations 3,991.3 5,002.4 Run-off Lines 336.6 356.9 Corporate and Other 216.6 146.2 Total $ 10,201.3 $ 10,514.5 Included in total assets at March 31, 2020 and December 31, 2019 are $719.3 million and $916.3 million, respectively, in assets associated with trade capital providers.

Senior Unsecured Fixed Rate Not

Senior Unsecured Fixed Rate Notes	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Senior Unsecured Fixed Rate Notes	Senior Unsecured Fixed Rate Notes In September 2012, Argo Group (the “Parent Guarantor”), through its subsidiary Argo Group US (the “Subsidiary Issuer”), issued $143,750,000 aggregate principal amount of the Subsidiary Issuer’s 6.5% Senior Notes due September 15, 2042 (the “Notes”). The Notes are unsecured and unsubordinated obligations of the Subsidiary Issuer and rank equally in right of payment with all of the Subsidiary Issuer’s other unsecured and unsubordinated debt. The Notes are guaranteed on a full and unconditional senior unsecured basis by the Parent Guarantor. The Notes may be redeemed, for cash, in whole or in part, on or after September 15, 2017, at the Subsidiary Issuer’s option, at any time and from time to time, prior to maturity at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued but unpaid interest on the principal amount being redeemed to, but not including, the redemption date. In accordance with ASU 2015-3, “Simplifying the Presentation of Debt Issuance Costs” (Topic 835), we present the unamortized debt issuance costs in the balance sheet as a direct deduction from the carrying value of the debt liability. At March 31, 2020 and December 31, 2019, the Notes consisted of the following: (in millions) March 31, 2020 December 31, 2019 Senior unsecured fixed rate notes Principal $ 143.8 $ 143.8 Less: unamortized debt issuance costs (3.8) (3.8) Senior unsecured fixed rate notes, less unamortized debt issuance costs $ 140.0 $ 140.0 In accordance with Article 10 of SEC Regulation S-X, we have elected to present condensed consolidating financial information in lieu of separate financial statements for the Subsidiary Issuer. The following tables present condensed consolidating financial information at March 31, 2020 and December 31, 2019 and for the three months ended March 31, 2020 and 2019, of the Parent Guarantor and the Subsidiary Issuer. The Subsidiary Issuer is an indirect wholly-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 certain of the debt of the Subsidiary Issuer. Condensed consolidating financial information of the Subsidiary Issuer is presented on a consolidated basis and consists principally of the net assets, results of operations and cash flows of operating insurance company subsidiaries. CONDENSED CONSOLIDATING BALANCE SHEET MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Assets Investments $ 0.3 $ 3,323.3 $ 1,487.8 $ — $ 4,811.4 Cash 1.8 40.4 116.5 — 158.7 Accrued investment income — 16.7 6.5 — 23.2 Premiums receivable — 264.4 474.7 — 739.1 Reinsurance recoverables — 1,724.9 1,096.0 — 2,820.9 Goodwill and other intangible assets, net 40.3 123.4 89.2 — 252.9 Deferred tax assets, net — 40.1 4.4 — 44.5 Deferred acquisition costs, net — 86.3 71.7 — 158.0 Ceded unearned premiums — 336.2 316.7 — 652.9 Operating lease right-of-use assets 7.1 57.5 24.5 — 89.1 Other assets 18.4 152.8 264.2 — 435.4 Assets held for sale — 15.2 — — 15.2 Intercompany note receivable — 57.4 (57.4) — — Investments in subsidiaries 1,796.7 — — (1,796.7) — Total assets $ 1,864.6 $ 6,238.6 $ 3,894.8 $ (1,796.7) $ 10,201.3 Liabilities and Shareholders' Equity Reserves for losses and loss adjustment expenses $ — $ 3,128.0 $ 1,939.6 $ — $ 5,067.6 Unearned premiums — 897.1 562.9 — 1,460.0 Funds held and ceded reinsurance payable, net — 691.7 463.1 — 1,154.8 Debt 153.4 284.3 139.8 — 577.5 Current income taxes payable, net — 23.1 (5.4) — 17.7 Accrued underwriting expenses and other liabilities 9.2 74.2 101.9 — 185.3 Operating lease liabilities 7.3 66.5 27.8 — 101.6 Due to (from) affiliates 57.9 (25.6) 25.6 (57.9) — Total liabilities 227.8 5,139.3 3,255.3 (57.9) 8,564.5 Total shareholders' equity 1,636.8 1,099.3 639.5 (1,738.8) 1,636.8 Total liabilities and shareholders' equity $ 1,864.6 $ 6,238.6 $ 3,894.8 $ (1,796.7) $ 10,201.3 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations. CONDENSED CONSOLIDATING BALANCE SHEET DECEMBER 31, 2019 (in millions) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Assets Investments $ 0.6 $ 3,405.6 $ 1,693.2 $ — $ 5,099.4 Cash 1.9 31.6 104.3 — 137.8 Accrued investment income — 18.2 7.5 — 25.7 Premiums receivable — 231.3 456.9 — 688.2 Reinsurance recoverables — 1,689.4 1,415.2 — 3,104.6 Goodwill and other intangible assets, net 40.6 123.4 89.2 — 253.2 Deferred tax assets, net — 0.4 5.7 — 6.1 Deferred acquisition costs, net — 88.4 71.8 — 160.2 Ceded unearned premiums — 306.4 238.6 — 545.0 Operating lease right-of-use assets 7.1 59.6 25.1 — 91.8 Other assets 7.8 165.8 213.5 — 387.1 Assets held for sale — 15.4 — — 15.4 Intercompany note receivable — 56.7 (56.7) — — Investments in subsidiaries 1,916.7 — — (1,916.7) — Total assets $ 1,974.7 $ 6,192.2 $ 4,264.3 $ (1,916.7) $ 10,514.5 Liabilities and Shareholders' Equity Reserves for losses and loss adjustment expenses $ — $ 3,037.5 $ 2,120.1 $ — $ 5,157.6 Unearned premiums — 899.8 511.1 — 1,410.9 Funds held and ceded reinsurance payable, net — 645.9 607.8 — 1,253.7 Debt 153.4 284.3 141.0 — 578.7 Current income taxes payable, net — 8.2 (7.4) — 0.8 Accrued underwriting expenses and other liabilities 13.6 87.6 124.8 — 226.0 Operating lease liabilities 7.3 68.9 29.5 — 105.7 Due to (from) affiliates 19.3 (13.4) 13.4 (19.3) — Total liabilities 193.6 5,018.8 3,540.3 (19.3) 8,733.4 Total shareholders' equity 1,781.1 1,173.4 724.0 (1,897.4) 1,781.1 Total liabilities and shareholders' equity $ 1,974.7 $ 6,192.2 $ 4,264.3 $ (1,916.7) $ 10,514.5 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations . CONDENSED CONSOLIDATING STATEMENT OF (LOSS) INCOME FOR THE THREE MONTHS ENDED MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Premiums and other revenue: Earned premiums $ — $ 301.5 $ 133.5 $ — $ 435.0 Net investment income — 24.6 10.9 — 35.5 Fee and other income — 0.8 1.3 — 2.1 Net realized investment (losses) gains (0.1) (40.6) 4.6 — (36.1) Total revenue (0.1) 286.3 150.3 — 436.5 Expenses: Losses and loss adjustment expenses — 190.5 90.4 — 280.9 Underwriting, acquisition and insurance expenses 5.8 101.8 60.4 — 168.0 Other corporate expenses 2.6 0.7 — — 3.3 Interest expense 1.4 4.3 2.0 — 7.7 Fee and other expense — 0.7 0.5 — 1.2 Foreign currency exchange gains — (1.0) (2.0) — (3.0) Total expenses 9.8 297.0 151.3 — 458.1 Loss before income taxes (9.9) (10.7) (1.0) — (21.6) (Benefit) provision for income taxes — (5.9) 3.1 — (2.8) Net loss before equity in earnings of subsidiaries (9.9) (4.8) (4.1) — (18.8) Equity in undistributed earnings of subsidiaries (8.9) — — 8.9 — Net loss $ (18.8) $ (4.8) $ (4.1) $ 8.9 $ (18.8) (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations. CONDENSED CONSOLIDATING STATEMENT OF INCOME FOR THE THREE MONTHS ENDED MARCH 31, 2019 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Premiums and other revenue: Earned premiums $ — $ 266.5 $ 154.0 $ — $ 420.5 Net investment (expense) income (0.7) 23.8 10.8 — 33.9 Fee and other income — 1.1 1.2 — 2.3 Net realized investment (losses) gains (0.1) 45.9 6.7 — 52.5 Total revenue (0.8) 337.3 172.7 — 509.2 Expenses: Losses and loss adjustment expenses — 158.0 79.9 — 237.9 Underwriting, acquisition and insurance expenses 0.2 104.1 55.9 — 160.2 Other corporate expenses 0.5 — — — 0.5 Interest expense 1.7 4.7 2.1 — 8.5 Fee and other expense — 0.8 0.5 — 1.3 Foreign currency exchange gains — 0.3 0.4 — 0.7 Total expenses 2.4 267.9 138.8 — 409.1 (Loss) income before income taxes (3.2) 69.4 33.9 — 100.1 Provision (benefit) for income taxes — 10.0 (1.1) — 8.9 Net (loss) income before equity in earnings of subsidiaries (3.2) 59.4 35.0 — 91.2 Equity in undistributed earnings of subsidiaries 94.4 — — (94.4) — Net income $ 91.2 $ 59.4 $ 35.0 $ (94.4) $ 91.2 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations . CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE THREE MONTHS ENDED MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Net cash flows from operating activities $ 10.0 $ 35.7 $ (77.1) $ — $ (31.4) Cash flows from investing activities: Proceeds from sales of investments — 309.4 328.7 — 638.1 Maturities and mandatory calls of fixed maturity investments — 100.5 57.7 — 158.2 Purchases of investments — (583.0) (266.2) — (849.2) Change in short-term investments and foreign regulatory deposits 0.3 128.8 (12.9) — 116.2 Settlements of foreign currency exchange forward contracts — — 3.1 — 3.1 Purchases of fixed assets and other, net — 17.4 (22.5) — (5.1) Cash provided by (used in) investing activities 0.3 (26.9) 87.9 — 61.3 Cash flows from financing activities: Activity under stock incentive plans 0.3 — — — 0.3 Payment of cash dividend to common shareholders (10.7) — — — (10.7) Cash used in financing activities (10.4) — — — (10.4) Effect of exchange rate changes on cash — — 1.4 — 1.4 Change in cash (0.1) 8.8 12.2 — 20.9 Cash, beginning of year 1.9 31.6 104.3 — 137.8 Cash, end of period $ 1.8 $ 40.4 $ 116.5 $ — $ 158.7 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE THREE MONTHS ENDED MARCH 31, 2019 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Net cash flows from operating activities $ 8.8 $ 29.5 $ 17.3 $ — $ 55.6 Cash flows from investing activities: Proceeds from sales of investments — 156.6 115.9 — 272.5 Maturities and mandatory calls of fixed maturity investments — 51.3 14.5 — 65.8 Purchases of investments — (249.0) (135.2) — (384.2) Change in short-term investments and foreign regulatory deposits 1.9 35.3 0.8 — 38.0 Settlements of foreign currency exchange forward contracts — 0.3 3.3 — 3.6 Purchases of fixed assets and other, net — (3.3) (24.1) — (27.4) Cash (used in) provided by investing activities 1.9 (8.8) (24.8) — (31.7) Cash flows from financing activities: Payment on the intercompany note — (19.1) 19.1 — — Activity under stock incentive plans 0.3 — — — 0.3 Payment of cash dividend to common shareholders (10.8) — — — (10.8) Cash (used in) provided by financing activities (10.5) (19.1) 19.1 — (10.5) Effect of exchange rate changes on cash — — 0.1 — 0.1 Change in cash 0.2 1.6 11.7 — 13.5 Cash, beginning of year 1.7 31.7 105.8 — 139.2 Cash, end of period $ 1.9 $ 33.3 $ 117.5 $ — $ 152.7 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On April 30, 2020, we closed on the previously announced sale of our Trident Public Risk Solutions (“Trident”) brand and underwriting platform to Paragon Insurance Holdings, LLC (“Paragon”) and received $38 million in cash, with additional consideration in future periods depending on performance post-closing. We will recognize a pre-tax gain of approximately $32 million related to the sale during the second quarter of 2020. Trident is one of the business units within our U.S. Operations reporting segment. Paragon will continue to write business on Argo paper through a managing general agency agreement, and we will retain Trident’s claims operations and provide claims services to Paragon for the public entity business.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of Argo Group International Holdings, Ltd. (“Argo Group,” “we” or the “Company”) and its subsidiaries have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance and reinsurance products in the property and casualty market. The preparation of interim financial statements in conformity with 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 reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our consolidated financial statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; estimates of written and earned premiums; reinsurance premium receivable; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of goodwill and intangibles and our deferred tax asset valuation allowance. Actual results could differ from those estimates. Certain financial information that normally is included in annual financial statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the Securities and Exchange Commission ("SEC") on February 28, 2020. The interim financial information as of, and for the three months ended, March 31, 2020 and 2019 is unaudited. However, in the opinion of management, the interim information includes all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the results presented for the interim periods. The operating results for the interim periods are not necessarily indicative of the results to be expected for the full year. All significant intercompany amounts have been eliminated in consolidation. Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation.
Reclassification	Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation.
Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-13, “Measurement of Credit Losses on Financial Instruments” (Topic 326), commonly referred to as current expected credit losses or "CECL." ASU 2016-13 requires organizations to estimate credit losses on certain types of financial instruments, including receivables and available-for-sale debt securities, by introducing an approach based on expected losses. The expected loss approach will require entities to incorporate considerations of historical information, current information and reasonable and supportable forecasts. The updated guidance also amends the previous other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within the year of adoption. The guidance requires a modified retrospective transition method. We adopted the updated guidance effective January 1, 2020 using the modified retrospective approach, which resulted in a $7.9 million net of tax reduction to retained earnings. Partially offsetting this reduction of retained earnings was a $5.7 million net of tax increase in other comprehensive income representing the reclassification of unrealized investment losses to credit losses under this accounting update. The cumulative effect adjustment decreased shareholders’ equity $2.2 million. In January 2020, the FASB issued ASU 2020-01, "Investments — Equity Securities" (Topic 321), "Investments — Equity Method and Joint Ventures" (Topic 323), and "Derivatives and Hedging" (Topic 815). ASU 2020-01 clarifies that entities that apply the measurement alternative in ASC 321 should consider observable transactions that result in entities initially applying or discontinuing the use of the equity method of accounting under ASC 323. The guidance also says that certain forward contracts and purchased options on equity securities that are not deemed to be in-substance common stock under ASC 323 or accounted for as derivatives under ASC 815 are in the scope of ASC 321. The guidance is effective for public business entities ("PBEs") for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years, with early adoption is permitted. The guidance should be applied prospectively. We are currently in the process of evaluating the impact that the adoption of the ASU will have on our financial results and disclosures, but it is not expected to have a material impact upon adoption. In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform" (Topic 848). ASU 2020-04 provides temporary optional expedients and exceptions to the US GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens of the expected market transition from the London Interbank Offered Rate (LIBOR) and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate. Entities can elect not to apply certain modification accounting requirements to contracts affected by what the guidance calls reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Entities can elect various optional expedients for hedging relationships affected by reference rate reform, if certain criteria are met. The guidance is effective upon issuance and generally can be applied through December 31, 2022. We have certain debt agreements for which the interest rate is based on LIBOR rates. We are currently investigating the impacts of the transition from LIBOR to other rates on these contracts and the resulting accounting requirements, but do not expect the change in rates to have a material impact on our financial statements. Updates to Accounting Policies The following accounting policies have been updated to reflect the adoption of ASU 2016-13, as described above. Investment Impairments of Available for Sale Fixed Maturities We regularly review our investments to identify and evaluate those that may have credit impairments. For fixed maturity securities, the evaluation for credit losses is generally based on the present value of expected cash flows of the security as compared to the amortized book value, the financial condition, near-term and long-term prospects for the issuer, including industry conditions, implications of rating agency actions, the likelihood of principal and interest recoverability and whether it is more likely than not we will be required to sell the investment prior to the anticipated recovery in value. Effective January 1, 2020 with the adoption of ASU 2016-13 Financial Instruments-Credit Losses, we recognize credit losses on fixed maturities through an allowance account. For fixed maturities that we do not intend to sell or for which it is more likely than not we will not be required to sell prior to the anticipated recovery in value, we separate the credit component of the impairment from the component related to all other market factors and report the credit loss component to net realized investment gains (losses) in the Consolidated Statement of Income. The impairment related to all other market factors is reported as a separate component of shareholder’s equity in other comprehensive income (loss). The credit loss allowance account is adjusted for any additional credit losses or subsequent recoveries and the cost basis of the fixed maturity security is not adjusted. For fixed maturity securities that we intend to sell or for which it is more likely that not that we will be required to sell before an anticipated recovery in value, the full amount of the impairment is recognized in net realized investment gains (losses) in the Consolidated Statement of Income and the cost basis of the fixed maturity security is adjusted to reflect the recognized realized loss. The new cost basis is not adjusted for any recoveries in fair value. We report accrued investment income separately from fixed maturity securities and have elected to not measure an allowance for credit losses for accrued investment income. The write-off of investment income accrued for fixed maturities that have defaulted on interest payments is recognized as a loss in net realized investment gains (losses), in the period of the default, in the Consolidated Statement of Income. Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. We report our reinsurance recoverables net of an allowance for estimated uncollectible reinsurance. The allowance is based upon our ongoing review of amounts outstanding, length of collection periods, changes in reinsurer credit standing, disputes, applicable coverage defenses and other relevant factors. We use the rating-based method to estimate the uncollectible reinsurance reserves due to credit losses. Under this method, reinsurance credit risk is estimated by considering the reinsurers probability of default. Reinsurance recoverables are forecasted out of the assumed billing periods and a liquidation factor is applied based on the rating of the reinsurer and adjusted as needed based on our historical experience with the reinsurers. Additionally, reinsurance receivable balances are evaluated to identify any dispute risk and when required, an additional reserve is recorded. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as any subsequent collections of amounts previously written off, are reported as part of underwriting expense. We evaluate and monitor the financial condition of its reinsurers under voluntary reinsurance arrangements to minimize its exposure to significant losses from reinsurer insolvencies. Premiums and Unearned Premium Reserves Premiums are recognized as revenues pro rata over the policy period. Unearned premium reserves represent the unexpired portion of policy premiums. Accrued retrospective premiums are included in premium balances receivable. Premiums receivable balances are reported net of an allowance for expected losses, both dispute and credit related. The allowance is based upon our ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. Credit risk is partially mitigated by our ability to cancel the policy if the policyholder does not pay the premium.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments	The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: March 31, 2020 (in millions) Amortized Gross Gross Allowance for Credit Losses (1) Fair Fixed maturities U.S. Governments $ 320.2 $ 18.5 $ — $ — $ 338.7 Foreign Governments 245.9 4.6 10.4 0.4 239.7 Obligations of states and political subdivisions 143.8 5.4 0.7 — 148.5 Corporate bonds 1,705.4 17.8 98.3 31.1 1,593.8 Commercial mortgage-backed securities 242.9 2.4 3.5 — 241.8 Residential mortgage-backed securities 534.0 18.8 6.4 — 546.4 Asset-backed securities 166.9 1.1 6.2 0.1 161.7 Collateralized loan obligations 275.3 0.4 22.8 — 252.9 Total fixed maturities $ 3,634.4 $ 69.0 $ 148.3 $ 31.6 $ 3,523.5 (1) Effective January 1, 2020 we adopted ASC-326 and as a result any credit impairment losses on our available-for-sale fixed maturities are recorded as an allowance, subject to reversal. Prior periods have not been restated to conform with the current year presentation. See Note 1. December 31, 2019 (in millions) Amortized Gross Gross Fair Fixed maturities U.S. Governments $ 353.5 $ 2.3 $ 1.2 $ 354.6 Foreign Governments 244.8 4.6 0.7 248.7 Obligations of states and political subdivisions 145.8 6.9 0.1 152.6 Corporate bonds 1,777.4 37.7 34.7 1,780.4 Commercial mortgage-backed securities 213.5 4.6 1.1 217.0 Residential mortgage-backed securities 479.1 10.4 0.6 488.9 Asset-backed securities 164.2 1.5 0.2 165.5 Collateralized loan obligations 226.7 0.5 1.4 225.8 Total fixed maturities $ 3,605.0 $ 68.5 $ 40.0 $ 3,633.5
Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity	The amortized cost and fair values of fixed maturity investments as of March 31, 2020, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 306.6 $ 301.6 Due after one year through five years 1,489.7 1,419.3 Due after five years through ten years 554.2 536.8 Thereafter 64.8 63.0 Structured securities 1,219.1 1,202.8 Total $ 3,634.4 $ 3,523.5
Schedule of Carrying Value And Unfunded Investment Commitments Of Other Invested Assets Portfolio	Details regarding the carrying value and unfunded investment commitments of other investments as of March 31, 2020 and December 31, 2019 were as follows: March 31, 2020 (in millions) Carrying Unfunded Investment Type Hedge funds $ 105.7 $ — Private equity 220.1 104.6 Overseas deposits 92.3 — Other 4.3 — Total other investments $ 422.4 $ 104.6 December 31, 2019 (in millions) Carrying Unfunded Investment Type Hedge funds $ 109.5 $ — Private equity 268.1 110.0 Overseas deposits 114.6 — Other 4.3 — Total other investments $ 496.5 $ 110.0
Schedule of Aging of Unrealized Losses on Company's Investments in Fixed Maturities, Equity Securities and Other Investments	An aging of unrealized losses on our investments in fixed maturities is presented below: March 31, 2020 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments (1) $ 1.4 $ — $ — $ — $ 1.4 $ — Foreign Governments 143.6 10.4 — — 143.6 10.4 Obligations of states and political subdivisions 24.2 0.7 — — 24.2 0.7 Corporate bonds 850.3 75.7 29.7 22.6 880.0 98.3 Commercial mortgage-backed securities 132.6 3.5 — — 132.6 3.5 Residential mortgage-backed securities 101.1 5.5 8.9 0.9 110.0 6.4 Asset-backed securities 103.3 5.8 4.7 0.4 108.0 6.2 Collateralized loan obligations 194.9 19.0 54.9 3.8 249.8 22.8 Total fixed maturities $ 1,551.4 $ 120.6 $ 98.2 $ 27.7 $ 1,649.6 $ 148.3 (1) Unrealized losses are less than $0.1 million. December 31, 2019 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 114.6 $ 1.1 $ 17.0 $ 0.1 $ 131.6 $ 1.2 Foreign Governments (1) 117.6 0.7 5.1 — 122.7 0.7 Obligations of states and political subdivisions (1) 0.7 — 2.1 0.1 2.8 0.1 Corporate bonds 249.4 18.9 63.6 15.8 313.0 34.7 Commercial mortgage-backed securities (1) 74.8 1.1 4.9 — 79.7 1.1 Residential mortgage-backed securities 66.9 0.3 25.2 0.3 92.1 0.6 Asset-backed securities 22.5 0.1 18.9 0.1 41.4 0.2 Collateralized loan obligations 54.7 0.8 116.7 0.6 171.4 1.4 Total fixed maturities $ 701.2 $ 23.0 $ 253.5 $ 17.0 $ 954.7 $ 40.0 (1) Unrealized losses are less than $0.1 million.
Debt Securities, Available-for-sale, Allowance for Credit Loss	The following table presents a reconciliation of the beginning and ending balances for the allowance for credit losses on available-for-sale fixed maturity securities: For the Three Months Ended (in millions) 2020 Beginning balance, January 1, 2020 $ — Additions related to initial adoption of accounting standard 6.9 Provision for expected credit losses 24.7 Reductions due to sales/defaults of credit-impaired securities — Ending balance, March 31, 2020 $ 31.6
Schedule of Company's Gross Realized Investment Gains (Losses)	The following table presents our gross realized investment gains (losses): For the Three Months Ended (in millions) 2020 2019 Realized gains on fixed maturities and other Fixed maturities $ 20.8 $ 3.6 Other investments 48.2 8.8 69.0 12.4 Realized losses on fixed maturities and other Fixed maturities (7.7) (2.4) Other investments (31.8) (8.1) Credit losses on fixed maturities (24.7) (4.3) (64.2) (14.8) Equity securities Net realized (losses) gains on equity securities (1.6) 0.7 Change in unrealized (losses) gains on equity securities held at the end of the period (39.3) 54.2 Net realized (losses) gains on equity securities (40.9) 54.9 Net realized investment (losses) gains before income taxes (36.1) 52.5 Income tax benefit (provision) 8.0 (9.7) Net realized investment (losses) gains net of income taxes $ (28.1) $ 42.8
Schedule Of Changes In Unrealized Appreciation (Depreciation)	Changes in unrealized (losses) gains related to investments are summarized as follows: For the Three Months Ended (in millions) 2020 2019 Change in unrealized (losses) gains Fixed maturities $ (111.8) $ 59.9 Other investments (14.2) — Other and short-term investments (0.2) — Net unrealized investment (losses) gains before income taxes (126.2) 59.9 Income tax benefit (provision) 19.2 (9.6) Net unrealized investment (losses) gains, net of income taxes $ (107.0) $ 50.3
Schedule of Fair Value of Foreign Currency Exchange Forward Contracts	The fair value of our foreign currency exchange forward contracts as of March 31, 2020 and December 31, 2019 was as follows: (in millions) March 31, 2020 December 31, 2019 Operational currency exposure $ 7.0 $ (0.8) Asset manager investment exposure 0.2 (0.3) Total return strategy (2.3) 2.2 Total $ 4.9 $ 1.1
Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts	The following table represents our gross investment realized gains and losses on our foreign currency exchange forward contracts: For the Three Months Ended (in millions) 2020 2019 Realized gains Operational currency exposure $ 5.4 $ 0.3 Asset manager investment exposure 0.8 1.1 Total return strategy 25.0 6.3 Gross realized investment gains 31.2 7.7 Realized losses Operational currency exposure (1.7) (2.1) Asset manager investment exposure (0.4) (0.2) Total return strategy (28.0) (4.7) Gross realized investment losses (30.1) (7.0) Net realized investment gains on foreign currency exchange forward contracts $ 1.1 $ 0.7
Schedule of Restricted Assets	The following table presents our components of restricted assets: (in millions) March 31, 2020 December 31, 2019 Securities on deposit for regulatory and other purposes $ 228.3 $ 192.5 Securities pledged as collateral for letters of credit and other 170.8 169.9 Securities and cash on deposit supporting Lloyd’s business 400.7 412.8 Total restricted investments $ 799.8 $ 775.2
Financial Assets Measured at Fair Value on Recurring Basis	Based on an analysis of the inputs, our financial assets measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 338.7 $ 336.6 $ 2.1 $ — Foreign Governments 239.7 — 239.7 — Obligations of states and political subdivisions 148.5 — 148.5 — Corporate bonds 1,593.8 — 1,586.4 7.4 Commercial mortgage-backed securities 241.8 — 241.8 — Residential mortgage-backed securities 546.4 — 546.4 — Asset-backed securities 161.7 — 161.7 — Collateralized loan obligations 252.9 — 252.9 — Total fixed maturities 3,523.5 336.6 3,179.5 7.4 Equity securities 132.9 127.2 — 5.7 Other investments 92.3 — 92.3 — Short-term investments 732.6 708.3 24.3 — $ 4,481.3 $ 1,172.1 $ 3,296.1 $ 13.1 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 354.6 $ 349.1 $ 5.5 $ — Foreign Governments 248.7 — 248.7 — Obligations of states and political subdivisions 152.6 — 152.6 — Corporate bonds 1,780.4 — 1,773.0 7.4 Commercial mortgage-backed securities 217.0 — 217.0 — Residential mortgage-backed securities 488.9 — 488.9 — Asset-backed securities 165.5 — 165.5 — Collateralized loan obligations 225.8 — 225.8 — Total fixed maturities 3,633.5 349.1 3,277.0 7.4 Equity securities 124.4 117.8 — 6.6 Other investments 400.2 — 400.2 — Short-term investments 845.0 823.5 21.5 — $ 5,003.1 $ 1,290.4 $ 3,698.7 $ 14.0 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs
Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3	A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Observable Inputs (Level 3) (in millions) Credit Financial Equity Total Beginning balance, January 1, 2020 $ 7.4 $ 6.6 $ 14.0 Transfers into Level 3 — — — Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — (0.9) (0.9) Purchases, issuances, sales, and settlements: Purchases — — — Issuances — — — Sales — — — Settlements — — — Ending balance, March 31, 2020 $ 7.4 $ 5.7 $ 13.1 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at March 31, 2020 $ — $ — $ — (in millions) Credit Financial Equity Total Beginning balance, January 1, 2019 $ 2.2 $ 8.2 $ 10.4 Transfers into Level 3 3.5 — 3.5 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income (0.4) (1.6) (2.0) Included in other comprehensive loss 0.6 — 0.6 Purchases, issuances, sales, and settlements: Purchases 1.9 — 1.9 Issuances — — — Sales (0.4) — (0.4) Settlements — — — Ending balance, December 31, 2019 $ 7.4 $ 6.6 $ 14.0 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2019 $ — $ — $ —

Allowance for Credit Losses (Ta

Allowance for Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Premium Receivable, Allowance for Credit Loss	The following table represents the balances of premiums receivable, net of allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months ended March 31, 2020. (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Balance, January 1, 2020 $ 688.2 $ 7.9 Cumulative effect of adoption of ASU 2016-13 at January 1, 2020 — Current period change for estimated uncollectible premiums 0.8 Write-offs of uncollectible premiums receivable — Balance, March 31, 2020 $ 739.1 $ 8.7
Reinsurance Recoverable, Allowance for Credit Loss	Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2020 and January 1, 2020, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2020. (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2020 $ 3,104.6 $ 1.1 Cumulative effect of adoption of ASU 2016-13 at January 1, 2020 2.5 Current period change for estimated uncollectible reinsurance — Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2020 $ 2,820.9 $ 3.6

Reserves for Losses and Loss _2

Reserves for Losses and Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): For the Three Months Ended (in millions) 2020 2019 Net reserves beginning of the year $ 2,722.7 $ 2,562.9 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 278.2 240.4 Prior accident years 2.7 (2.5) Losses and LAE incurred during calendar year, net of reinsurance 280.9 237.9 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 72.6 34.7 Prior accident years 263.8 221.0 Losses and LAE payments made during current calendar year, net of reinsurance: 336.4 255.7 Change in participation interest (1) 32.5 (14.6) Foreign exchange adjustments (25.6) (9.1) Net reserves - end of period 2,674.1 2,521.4 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,393.5 2,147.5 Gross reserves - end of period $ 5,067.6 $ 4,668.9 (1) Amount represents the change in reserves due to changing our participation in Syndicates 1200 and 1910.
Impact from (Favorable) Unfavorable Development of Prior Accident Years’ Loss and LAE Reserves on Each Reporting Segment	The impact from the unfavorable (favorable) development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: For the Three Months Ended (in millions) 2020 2019 U.S. Operations $ 3.3 $ (4.0) International Operations (0.4) 0.8 Run-off Lines (0.2) 0.7 Total unfavorable (favorable) prior-year development $ 2.7 $ (2.5)

Disclosures about Fair Value _2

Disclosures about Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value	A summary of our financial instruments whose carrying value did not equal fair value is shown below: March 31, 2020 December 31, 2019 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 172.7 $ 173.6 $ 172.7 $ 174.0 Subordinated debentures 84.8 92.3 84.7 92.5 Total junior subordinated debentures 257.5 265.9 257.4 266.5 Senior unsecured fixed rate notes 140.0 125.9 140.0 144.2 Floating rate loan stock 55.0 55.3 56.3 56.8
Fair Value, Assets Measured on Recurring and Nonrecurring Basis	Based on an analysis of the inputs, our financial instruments measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, 2020 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 173.6 $ — $ 173.6 $ — Subordinated debentures 92.3 — 92.3 — Total junior subordinated debentures 265.9 — 265.9 — Senior unsecured fixed rate notes 125.9 125.9 — — Floating rate loan stock 55.3 — 55.3 — 447.1 125.9 321.2 — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2019 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 174.0 $ — $ 174.0 $ — Subordinated debentures 92.5 — 92.5 — Total junior subordinated debentures 266.5 — 266.5 — Senior unsecured fixed rate notes 144.2 144.2 — — Floating rate loan stock 56.8 — 56.8 — 467.5 144.2 323.3 — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive (Loss) Income (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Changes in Accumulated Other Comprehensive (Loss) Income	A summary of changes in accumulated other comprehensive (loss) income, net of taxes (where applicable) by component for the three months ended March 31, 2020, and 2019 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2020 $ (22.6) $ 33.5 $ (8.1) $ 2.8 Other comprehensive loss before reclassifications (3.4) (101.7) — (105.1) Amounts reclassified from accumulated other comprehensive loss — (5.3) — (5.3) Net current-period other comprehensive loss (3.4) (107.0) — (110.4) Cumulative effect of adoption of ASU 2016-13 — 5.7 — 5.7 Balance at March 31, 2020 $ (26.0) $ (67.8) $ (8.1) $ (101.9) (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2019 $ (22.4) $ (49.0) $ (6.7) $ (78.1) Other comprehensive income before reclassifications 0.2 47.7 — 47.9 Amounts reclassified from accumulated other comprehensive income — 2.6 — 2.6 Net current-period other comprehensive income 0.2 50.3 — 50.5 Balance at March 31, 2019 $ (22.2) $ 1.3 $ (6.7) $ (27.6)
Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income	The amounts reclassified from accumulated other comprehensive (loss) income shown in the above table have been included in the following captions in our Consolidated Statements of (Loss) Income: For the Three Months Ended (in millions) 2020 2019 Unrealized gains and losses on securities: Net realized investment (gains) loss $ (3.4) $ 3.1 Benefit for income taxes (1.9) (0.5) Net of taxes $ (5.3) $ 2.6

Net (Loss) Income Per Common _2

Net (Loss) Income Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share on Basic and Diluted Basis	The following table presents the calculation of net (loss) income per common share on a basic and diluted basis: For the Three Months Ended (in millions, except number of shares and per share amounts) 2020 2019 Net (loss) income $ (18.8) $ 91.2 Weighted average common shares outstanding - basic 34,469,516 33,984,329 Effect of dilutive securities: Equity compensation awards — 753,610 Weighted average common shares outstanding - diluted 34,469,516 34,737,939 Net (loss) income per common share: Basic $ (0.55) $ 2.68 Diluted $ (0.55) $ 2.63

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Schedule of Interest Paid and Income Taxes Paid (Recovered)	Interest paid and income taxes paid (recovered) were as follows: For the Three Months Ended (in millions) 2020 2019 Senior unsecured fixed rate notes $ 2.3 $ 2.3 Junior subordinated debentures 3.7 4.1 Other indebtedness 1.9 2.4 Total interest paid $ 7.9 $ 8.8 Income taxes paid 0.3 0.2 Income taxes recovered — — Income taxes paid, net $ 0.3 $ 0.2

Share-based Compensation (Table

Share-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Restricted Share Activity	A summary of restricted share activity as of March 31, 2020 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2020 471,271 $ 60.09 Vested and issued (134,983) $ 55.87 Expired or forfeited (45,482) $ 61.19 Outstanding at March 31, 2020 290,806 $ 61.94
Stock Settled Share Appreciation Rights	A summary of stock-settled SARs activity as of March 31, 2020 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2020 625,368 $ 33.60 Exercised (369,362) $ 32.59 Expired or forfeited — $ — Outstanding at March 31, 2020 256,006 $ 35.05

Underwriting, Acquisition and_2

Underwriting, Acquisition and Insurance Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Underwriting Acquisition And Insurance Expenses [Abstract]
Underwriting, Acquisition and Insurance Expenses	Underwriting, acquisition and insurance expenses were as follows: For the Three Months Ended (in millions) 2020 2019 Commissions $ 65.3 $ 63.3 General expenses 98.9 88.6 Premium taxes, boards and bureaus 8.0 8.3 172.2 160.2 Net deferral of policy acquisition costs (4.2) — Total underwriting, acquisition and insurance expenses $ 168.0 $ 160.2

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates	For the three months ended March 31, 2020 and 2019, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: For the Three Months Ended March 31, 2020 2019 (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ (21.7) — % $ 32.0 — % United States (10.7) 55.0 % 69.4 14.4 % United Kingdom 1.7 183.2 % (3.5) 31.5 % Belgium — (1) 68.8 % — (1) 30.8 % Brazil 2.2 — % 1.8 — % United Arab Emirates 0.9 — % 0.2 — % Ireland — (1) — % — (1) — % Italy 3.4 — % (0.7) — % Malta 2.6 — % 0.9 — % Luxembourg — — % — — % Switzerland — (1) — % — (1) — % Pre-tax (loss) income $ (21.6) 12.8 % $ 100.1 8.9 % (1) Pre-tax income (loss) for the respective year was less than $0.1 million.
Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate	A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate is as follows: For the Three Months Ended (in millions) 2020 2019 Income tax provision (benefit) at expected rate $ 0.8 $ 14.9 Tax effect of: Nontaxable investment income (0.1) (0.4) Foreign exchange adjustments (2.0) 0.5 Withholding taxes — (1) — (1) Prior period adjustments — (1) — Change in valuation allowance — (1) (0.6) Other (1.5) (5.5) Income tax (benefit) provision $ (2.8) $ 8.9 (1) Tax effect of the adjustment for the respective year was less than $0.1 million.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Revenue and Income (Loss) Before Income Taxes for Each Segment	Revenue and (loss) income before income taxes for each segment were as follows: For the Three Months Ended (in millions) 2020 2019 Revenue: Earned premiums U.S. Operations $ 302.5 $ 273.8 International Operations 132.3 146.7 Run-off Lines 0.2 — Total earned premiums 435.0 420.5 Net investment income U.S. Operations 25.2 23.1 International Operations 8.6 9.1 Run-off Lines 1.2 1.4 Corporate and Other 0.5 0.3 Total net investment income 35.5 33.9 Fee and other income 2.1 2.3 Net realized investment (losses) gains (36.1) 52.5 Total revenue $ 436.5 $ 509.2 For the Three Months Ended (in millions) 2020 2019 Income (loss) before income taxes U.S. Operations $ 36.9 $ 42.9 International Operations (12.3) 16.2 Run-off Lines 0.5 0.6 Total segment income before taxes 25.1 59.7 Corporate and Other (10.3) (10.9) Net realized investment and other (losses) gains (36.1) 52.5 Foreign currency exchange gains (loss) 3.0 (0.7) Other corporate expenses (3.3) (0.5) Total (loss) income before income taxes $ (21.6) $ 100.1
Schedule of Earned Premiums by Geographic Location	The table below presents earned premiums by geographic location for the three months ended March 31, 2020 and 2019. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. For the Three Months Ended (in millions) 2020 2019 United States $ 299.7 $ 272.6 United Kingdom 86.7 97.1 Bermuda 21.2 16.6 Malta 11.8 20.8 All other jurisdictions 15.6 13.4 Total earned premiums $ 435.0 $ 420.5
Identifiable Assets	The following table represents identifiable assets: (in millions) March 31, 2020 December 31, 2019 U.S. Operations $ 5,656.8 $ 5,009.0 International Operations 3,991.3 5,002.4 Run-off Lines 336.6 356.9 Corporate and Other 216.6 146.2 Total $ 10,201.3 $ 10,514.5

Senior Unsecured Fixed Rate N_2

Senior Unsecured Fixed Rate Notes (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule Of Unamortized Debt Issuance Costs Deducted From Carrying Value Of Debt Liability	At March 31, 2020 and December 31, 2019, the Notes consisted of the following: (in millions) March 31, 2020 December 31, 2019 Senior unsecured fixed rate notes Principal $ 143.8 $ 143.8 Less: unamortized debt issuance costs (3.8) (3.8) Senior unsecured fixed rate notes, less unamortized debt issuance costs $ 140.0 $ 140.0
Condensed Consolidating Balance Sheet	CONDENSED CONSOLIDATING BALANCE SHEET MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Assets Investments $ 0.3 $ 3,323.3 $ 1,487.8 $ — $ 4,811.4 Cash 1.8 40.4 116.5 — 158.7 Accrued investment income — 16.7 6.5 — 23.2 Premiums receivable — 264.4 474.7 — 739.1 Reinsurance recoverables — 1,724.9 1,096.0 — 2,820.9 Goodwill and other intangible assets, net 40.3 123.4 89.2 — 252.9 Deferred tax assets, net — 40.1 4.4 — 44.5 Deferred acquisition costs, net — 86.3 71.7 — 158.0 Ceded unearned premiums — 336.2 316.7 — 652.9 Operating lease right-of-use assets 7.1 57.5 24.5 — 89.1 Other assets 18.4 152.8 264.2 — 435.4 Assets held for sale — 15.2 — — 15.2 Intercompany note receivable — 57.4 (57.4) — — Investments in subsidiaries 1,796.7 — — (1,796.7) — Total assets $ 1,864.6 $ 6,238.6 $ 3,894.8 $ (1,796.7) $ 10,201.3 Liabilities and Shareholders' Equity Reserves for losses and loss adjustment expenses $ — $ 3,128.0 $ 1,939.6 $ — $ 5,067.6 Unearned premiums — 897.1 562.9 — 1,460.0 Funds held and ceded reinsurance payable, net — 691.7 463.1 — 1,154.8 Debt 153.4 284.3 139.8 — 577.5 Current income taxes payable, net — 23.1 (5.4) — 17.7 Accrued underwriting expenses and other liabilities 9.2 74.2 101.9 — 185.3 Operating lease liabilities 7.3 66.5 27.8 — 101.6 Due to (from) affiliates 57.9 (25.6) 25.6 (57.9) — Total liabilities 227.8 5,139.3 3,255.3 (57.9) 8,564.5 Total shareholders' equity 1,636.8 1,099.3 639.5 (1,738.8) 1,636.8 Total liabilities and shareholders' equity $ 1,864.6 $ 6,238.6 $ 3,894.8 $ (1,796.7) $ 10,201.3 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations. CONDENSED CONSOLIDATING BALANCE SHEET DECEMBER 31, 2019 (in millions) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Assets Investments $ 0.6 $ 3,405.6 $ 1,693.2 $ — $ 5,099.4 Cash 1.9 31.6 104.3 — 137.8 Accrued investment income — 18.2 7.5 — 25.7 Premiums receivable — 231.3 456.9 — 688.2 Reinsurance recoverables — 1,689.4 1,415.2 — 3,104.6 Goodwill and other intangible assets, net 40.6 123.4 89.2 — 253.2 Deferred tax assets, net — 0.4 5.7 — 6.1 Deferred acquisition costs, net — 88.4 71.8 — 160.2 Ceded unearned premiums — 306.4 238.6 — 545.0 Operating lease right-of-use assets 7.1 59.6 25.1 — 91.8 Other assets 7.8 165.8 213.5 — 387.1 Assets held for sale — 15.4 — — 15.4 Intercompany note receivable — 56.7 (56.7) — — Investments in subsidiaries 1,916.7 — — (1,916.7) — Total assets $ 1,974.7 $ 6,192.2 $ 4,264.3 $ (1,916.7) $ 10,514.5 Liabilities and Shareholders' Equity Reserves for losses and loss adjustment expenses $ — $ 3,037.5 $ 2,120.1 $ — $ 5,157.6 Unearned premiums — 899.8 511.1 — 1,410.9 Funds held and ceded reinsurance payable, net — 645.9 607.8 — 1,253.7 Debt 153.4 284.3 141.0 — 578.7 Current income taxes payable, net — 8.2 (7.4) — 0.8 Accrued underwriting expenses and other liabilities 13.6 87.6 124.8 — 226.0 Operating lease liabilities 7.3 68.9 29.5 — 105.7 Due to (from) affiliates 19.3 (13.4) 13.4 (19.3) — Total liabilities 193.6 5,018.8 3,540.3 (19.3) 8,733.4 Total shareholders' equity 1,781.1 1,173.4 724.0 (1,897.4) 1,781.1 Total liabilities and shareholders' equity $ 1,974.7 $ 6,192.2 $ 4,264.3 $ (1,916.7) $ 10,514.5 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations .
Condensed Consolidating Statement of Income	CONDENSED CONSOLIDATING STATEMENT OF (LOSS) INCOME FOR THE THREE MONTHS ENDED MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Premiums and other revenue: Earned premiums $ — $ 301.5 $ 133.5 $ — $ 435.0 Net investment income — 24.6 10.9 — 35.5 Fee and other income — 0.8 1.3 — 2.1 Net realized investment (losses) gains (0.1) (40.6) 4.6 — (36.1) Total revenue (0.1) 286.3 150.3 — 436.5 Expenses: Losses and loss adjustment expenses — 190.5 90.4 — 280.9 Underwriting, acquisition and insurance expenses 5.8 101.8 60.4 — 168.0 Other corporate expenses 2.6 0.7 — — 3.3 Interest expense 1.4 4.3 2.0 — 7.7 Fee and other expense — 0.7 0.5 — 1.2 Foreign currency exchange gains — (1.0) (2.0) — (3.0) Total expenses 9.8 297.0 151.3 — 458.1 Loss before income taxes (9.9) (10.7) (1.0) — (21.6) (Benefit) provision for income taxes — (5.9) 3.1 — (2.8) Net loss before equity in earnings of subsidiaries (9.9) (4.8) (4.1) — (18.8) Equity in undistributed earnings of subsidiaries (8.9) — — 8.9 — Net loss $ (18.8) $ (4.8) $ (4.1) $ 8.9 $ (18.8) (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations. CONDENSED CONSOLIDATING STATEMENT OF INCOME FOR THE THREE MONTHS ENDED MARCH 31, 2019 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Premiums and other revenue: Earned premiums $ — $ 266.5 $ 154.0 $ — $ 420.5 Net investment (expense) income (0.7) 23.8 10.8 — 33.9 Fee and other income — 1.1 1.2 — 2.3 Net realized investment (losses) gains (0.1) 45.9 6.7 — 52.5 Total revenue (0.8) 337.3 172.7 — 509.2 Expenses: Losses and loss adjustment expenses — 158.0 79.9 — 237.9 Underwriting, acquisition and insurance expenses 0.2 104.1 55.9 — 160.2 Other corporate expenses 0.5 — — — 0.5 Interest expense 1.7 4.7 2.1 — 8.5 Fee and other expense — 0.8 0.5 — 1.3 Foreign currency exchange gains — 0.3 0.4 — 0.7 Total expenses 2.4 267.9 138.8 — 409.1 (Loss) income before income taxes (3.2) 69.4 33.9 — 100.1 Provision (benefit) for income taxes — 10.0 (1.1) — 8.9 Net (loss) income before equity in earnings of subsidiaries (3.2) 59.4 35.0 — 91.2 Equity in undistributed earnings of subsidiaries 94.4 — — (94.4) — Net income $ 91.2 $ 59.4 $ 35.0 $ (94.4) $ 91.2 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations .
Condensed Consolidating Statement of Cash Flows	CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE THREE MONTHS ENDED MARCH 31, 2020 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Net cash flows from operating activities $ 10.0 $ 35.7 $ (77.1) $ — $ (31.4) Cash flows from investing activities: Proceeds from sales of investments — 309.4 328.7 — 638.1 Maturities and mandatory calls of fixed maturity investments — 100.5 57.7 — 158.2 Purchases of investments — (583.0) (266.2) — (849.2) Change in short-term investments and foreign regulatory deposits 0.3 128.8 (12.9) — 116.2 Settlements of foreign currency exchange forward contracts — — 3.1 — 3.1 Purchases of fixed assets and other, net — 17.4 (22.5) — (5.1) Cash provided by (used in) investing activities 0.3 (26.9) 87.9 — 61.3 Cash flows from financing activities: Activity under stock incentive plans 0.3 — — — 0.3 Payment of cash dividend to common shareholders (10.7) — — — (10.7) Cash used in financing activities (10.4) — — — (10.4) Effect of exchange rate changes on cash — — 1.4 — 1.4 Change in cash (0.1) 8.8 12.2 — 20.9 Cash, beginning of year 1.9 31.6 104.3 — 137.8 Cash, end of period $ 1.8 $ 40.4 $ 116.5 $ — $ 158.7 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE THREE MONTHS ENDED MARCH 31, 2019 (in millions) (Unaudited) Argo Group Argo Group US, Inc. Other Subsidiaries and Eliminations (1) Consolidating Adjustments (2) Total Net cash flows from operating activities $ 8.8 $ 29.5 $ 17.3 $ — $ 55.6 Cash flows from investing activities: Proceeds from sales of investments — 156.6 115.9 — 272.5 Maturities and mandatory calls of fixed maturity investments — 51.3 14.5 — 65.8 Purchases of investments — (249.0) (135.2) — (384.2) Change in short-term investments and foreign regulatory deposits 1.9 35.3 0.8 — 38.0 Settlements of foreign currency exchange forward contracts — 0.3 3.3 — 3.6 Purchases of fixed assets and other, net — (3.3) (24.1) — (27.4) Cash (used in) provided by investing activities 1.9 (8.8) (24.8) — (31.7) Cash flows from financing activities: Payment on the intercompany note — (19.1) 19.1 — — Activity under stock incentive plans 0.3 — — — 0.3 Payment of cash dividend to common shareholders (10.8) — — — (10.8) Cash (used in) provided by financing activities (10.5) (19.1) 19.1 — (10.5) Effect of exchange rate changes on cash — — 0.1 — 0.1 Change in cash 0.2 1.6 11.7 — 13.5 Cash, beginning of year 1.7 31.7 105.8 — 139.2 Cash, end of period $ 1.9 $ 33.3 $ 117.5 $ — $ 152.7 (1) Includes all other subsidiaries of Argo Group International Holdings, Ltd. and all intercompany eliminations. (2) Includes all Argo Group parent company eliminations.

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Other corporate expenses	$ 3.3	$ 0.5	$ 3.3

Recently Adopted Accounting P_2

Recently Adopted Accounting Pronouncements (Details) - ASU 2016-13 [Member] $ in Millions	Jan. 01, 2020USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU 2016-13, net of taxes	$ (2.2)
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU 2016-13, net of taxes	(7.9)
Accumulated Other Comprehensive Income (Loss) Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU 2016-13, net of taxes	$ 5.7

Investments - Additional Inform

Investments - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)security	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)
Investments, Debt and Equity Securities [Abstract]
Fair value of investments, assets managed on behalf of the trade capital providers | $	$ 120.9		$ 158.6
Number of securities in an unrealized loss position, total | security	4,842
Number of securities in an unrealized loss position for less than one year | security	2,480
Number of securities in an unrealized loss position for a period of one year or greater | security	194
Provision for expected credit losses | $	$ 24.7
Impairment losses | $	$ 0	$ 4.3

Investments - Schedule of Amort

Investments - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fixed maturities
Amortized cost	$ 3,634.4	$ 3,605
Allowance for Credit Losses	31.6	0
Fair Value	3,523.5	3,633.5	[1]
Fixed Maturities [Member]
Fixed maturities
Amortized cost	3,634.4	3,605
Gross Unrealized Gains	69	68.5
Gross Unrealized Losses	148.3	40
Allowance for Credit Losses	31.6
Fair Value	3,523.5	3,633.5
Fixed Maturities [Member] | U.S. Governments [Member]
Fixed maturities
Amortized cost	320.2	353.5
Gross Unrealized Gains	18.5	2.3
Gross Unrealized Losses	0	1.2
Allowance for Credit Losses	0
Fair Value	338.7	354.6
Fixed Maturities [Member] | Foreign Governments [Member]
Fixed maturities
Amortized cost	245.9	244.8
Gross Unrealized Gains	4.6	4.6
Gross Unrealized Losses	10.4	0.7
Allowance for Credit Losses	0.4
Fair Value	239.7	248.7
Fixed Maturities [Member] | Obligations of States and Political Subdivisions [Member]
Fixed maturities
Amortized cost	143.8	145.8
Gross Unrealized Gains	5.4	6.9
Gross Unrealized Losses	0.7	0.1
Allowance for Credit Losses	0
Fair Value	148.5	152.6
Fixed Maturities [Member] | Corporate Bonds [Member]
Fixed maturities
Amortized cost	1,705.4	1,777.4
Gross Unrealized Gains	17.8	37.7
Gross Unrealized Losses	98.3	34.7
Allowance for Credit Losses	31.1
Fair Value	1,593.8	1,780.4
Fixed Maturities [Member] | Commercial Mortgage-backed Securities [Member]
Fixed maturities
Amortized cost	242.9	213.5
Gross Unrealized Gains	2.4	4.6
Gross Unrealized Losses	3.5	1.1
Allowance for Credit Losses	0
Fair Value	241.8	217
Fixed Maturities [Member] | Residential Mortgage-backed Securities [Member]
Fixed maturities
Amortized cost	534	479.1
Gross Unrealized Gains	18.8	10.4
Gross Unrealized Losses	6.4	0.6
Allowance for Credit Losses	0
Fair Value	546.4	488.9
Fixed Maturities [Member] | Asset-backed Securities [Member]
Fixed maturities
Amortized cost	166.9	164.2
Gross Unrealized Gains	1.1	1.5
Gross Unrealized Losses	6.2	0.2
Allowance for Credit Losses	0.1
Fair Value	161.7	165.5
Fixed Maturities [Member] | Collateralized Debt Obligations [Member]
Fixed maturities
Amortized cost	275.3	226.7
Gross Unrealized Gains	0.4	0.5
Gross Unrealized Losses	22.8	1.4
Allowance for Credit Losses	0
Fair Value	$ 252.9	$ 225.8
[1]	Derived from audited consolidated financial statements.

Investments - Schedule of Amo_2

Investments - Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity (Detail) $ in Millions	Mar. 31, 2020USD ($)
Amortized Cost
Due in one year or less	$ 306.6
Due after one year through five years	1,489.7
Due after five years through ten years	554.2
Thereafter	64.8
Structured securities	1,219.1
Total	3,634.4
Fair Value
Due in one year or less	301.6
Due after one year through five years	1,419.3
Due after five years through ten years	536.8
Thereafter	63
Structured securities	1,202.8
Total	$ 3,523.5

Investments - Schedule of Carry

Investments - Schedule of Carrying Value and Unfunded Investment Commitments of Other Invested Assets Portfolio (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Carrying Value	$ 4,811.4	$ 5,099.4	[1]
Hedge funds [Member]
Schedule of Investments [Line Items]
Carrying Value	105.7	109.5
Unfunded Commitments	0	0
Private equity [Member]
Schedule of Investments [Line Items]
Carrying Value	220.1	268.1
Unfunded Commitments	104.6	110
Overseas Deposits [Member]
Schedule of Investments [Line Items]
Carrying Value	92.3	114.6
Unfunded Commitments	0	0
Other [Member]
Schedule of Investments [Line Items]
Carrying Value	4.3	4.3
Unfunded Commitments	0	0
Other Investments [Member]
Schedule of Investments [Line Items]
Carrying Value	422.4	496.5
Unfunded Commitments	$ 104.6	$ 110
[1]	Derived from audited consolidated financial statements.

Investments - Schedule of Aging

Investments - Schedule of Aging of Unrealized Losses on Company's Investments in Fixed Maturities, Equity Securities and Other Investments (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	$ 1,551.4	$ 701.2
Unrealized Losses, Less Than One Year	120.6	23
Fair Value, One Year or Greater	98.2	253.5
Unrealized Losses, One Year or Greater	27.7	17
Fair Value, Total	1,649.6	954.7
Unrealized Losses, Total	148.3	40
U.S. Governments [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	1.4	114.6
Unrealized Losses, Less Than One Year	0	1.1
Fair Value, One Year or Greater	0	17
Unrealized Losses, One Year or Greater	0	0.1
Fair Value, Total	1.4	131.6
Unrealized Losses, Total	0	1.2
Foreign Governments [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	143.6	117.6
Unrealized Losses, Less Than One Year	10.4	0.7
Fair Value, One Year or Greater	0	5.1
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	143.6	122.7
Unrealized Losses, Total	10.4	0.7
Obligations of States and Political Subdivisions [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	24.2	0.7
Unrealized Losses, Less Than One Year	0.7	0
Fair Value, One Year or Greater	0	2.1
Unrealized Losses, One Year or Greater	0	0.1
Fair Value, Total	24.2	2.8
Unrealized Losses, Total	0.7	0.1
Corporate Bonds [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	850.3	249.4
Unrealized Losses, Less Than One Year	75.7	18.9
Fair Value, One Year or Greater	29.7	63.6
Unrealized Losses, One Year or Greater	22.6	15.8
Fair Value, Total	880	313
Unrealized Losses, Total	98.3	34.7
Commercial Mortgage-backed Securities [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	132.6	74.8
Unrealized Losses, Less Than One Year	3.5	1.1
Fair Value, One Year or Greater	0	4.9
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	132.6	79.7
Unrealized Losses, Total	3.5	1.1
Residential Mortgage-backed Securities [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	101.1	66.9
Unrealized Losses, Less Than One Year	5.5	0.3
Fair Value, One Year or Greater	8.9	25.2
Unrealized Losses, One Year or Greater	0.9	0.3
Fair Value, Total	110	92.1
Unrealized Losses, Total	6.4	0.6
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	103.3	22.5
Unrealized Losses, Less Than One Year	5.8	0.1
Fair Value, One Year or Greater	4.7	18.9
Unrealized Losses, One Year or Greater	0.4	0.1
Fair Value, Total	108	41.4
Unrealized Losses, Total	6.2	0.2
Collateralized Debt Obligations [Member]
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	194.9	54.7
Unrealized Losses, Less Than One Year	19	0.8
Fair Value, One Year or Greater	54.9	116.7
Unrealized Losses, One Year or Greater	3.8	0.6
Fair Value, Total	249.8	171.4
Unrealized Losses, Total	$ 22.8	$ 1.4

Investments - Allowance for Cre

Investments - Allowance for Credit Losses (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, January 1, 2020	$ 0
Provision for expected credit losses	24.7
Reductions due to sales/defaults of credit-impaired securities	0
Ending balance, March 31, 2020	31.6
Cumulative Effect, Period Of Adoption, Adjustment
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, January 1, 2020	$ 6.9

Investments - Schedule of Compa

Investments - Schedule of Company's Gross Realized Investment Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	$ 69	$ 12.4
Realized losses on fixed maturities and other	(64.2)	(14.8)
Credit losses on fixed maturities	24.7	0
Net realized (losses) gains on equity securities	(1.6)	0.7
Change in unrealized (losses) gains on equity securities held at the end of the period	(39.3)	54.2
Net realized (losses) gains on equity securities	(40.9)	54.9
Net realized investment (losses) gains before income taxes	(36.1)	52.5
Income tax benefit (provision)	8	(9.7)
Net realized investment (losses) gains net of income taxes	(28.1)	42.8
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	20.8	3.6
Realized losses on fixed maturities and other	(7.7)	(2.4)
Other Investments [Member]
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	48.2	8.8
Realized losses on fixed maturities and other	(31.8)	(8.1)
Other-Than-Temporary Impairment Losses on Fixed Maturities [Member]
Schedule of Investments [Line Items]
Credit losses on fixed maturities	$ 24.7	$ 4.3

Investments - Schedule of Chang

Investments - Schedule of Changes in Unrealized Appreciation (Depreciation) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Net unrealized investment (losses) gains before income taxes	$ (126.2)	$ 59.9
Income tax benefit (provision)	19.2	(9.6)
Net unrealized investment (losses) gains, net of income taxes	(107)	50.3
Fixed Maturities [Member]
Schedule of Investments [Line Items]
Net unrealized investment (losses) gains before income taxes	(111.8)	59.9
Other Investment [Member]
Schedule of Investments [Line Items]
Net unrealized investment (losses) gains before income taxes	(14.2)	0
Short-term Investments [Member]
Schedule of Investments [Line Items]
Net unrealized investment (losses) gains before income taxes	$ (0.2)	$ 0

Investments - Schedule of Fair

Investments - Schedule of Fair Value of Foreign Currency Exchange Forward Contracts (Detail) - Foreign Currency Exchange Forward Contracts [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ 4.9	$ 1.1
Operational Currency Exposure [Member]
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	7	(0.8)
Asset Manager Investment Exposure [Member]
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	0.2	(0.3)
Total return strategy [Member]
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ (2.3)	$ 2.2

Investments - Schedule of Reali

Investments - Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts (Detail) - Foreign Currency Exchange Forward Contracts [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Gross realized investment gains	$ 31.2	$ 7.7
Gross realized investment losses	(30.1)	(7)
Net realized investment gains on foreign currency exchange forward contracts	1.1	0.7
Operational Currency Exposure [Member]
Schedule of Investments [Line Items]
Gross realized investment gains	5.4	0.3
Gross realized investment losses	(1.7)	(2.1)
Asset Manager Investment Exposure [Member]
Schedule of Investments [Line Items]
Gross realized investment gains	0.8	1.1
Gross realized investment losses	(0.4)	(0.2)
Total return strategy [Member]
Schedule of Investments [Line Items]
Gross realized investment gains	25	6.3
Gross realized investment losses	$ (28)	$ (4.7)

Investments - Components of Res

Investments - Components of Restricted Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities pledged as collateral for letters of credit and other	$ 170.8	$ 169.9
Securities and cash on deposit supporting Lloyd’s business	400.7	412.8
Total restricted investments	799.8	775.2
Securities Deposits For Regulatory and Other Purposes [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities on deposit for regulatory and other purposes	$ 228.3	$ 192.5

Investments - Financial Assets

Investments - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 4,811.4	$ 5,099.4	[1]
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	422.4	496.5
Fair Value, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	4,481.3	5,003.1
Fair Value, Recurring [Member] | Fixed Maturities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	3,523.5	3,633.5
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	252.9	225.8
Fair Value, Recurring [Member] | Fixed Maturities [Member] | U.S. Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	338.7	354.6
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Foreign Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	239.7	248.7
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	148.5	152.6
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,593.8	1,780.4
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	241.8	217
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	546.4	488.9
Fair Value, Recurring [Member] | Fixed Maturities [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	161.7	165.5
Fair Value, Recurring [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	132.9	124.4
Fair Value, Recurring [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	92.3	400.2
Fair Value, Recurring [Member] | Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	732.6	845
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,172.1	1,290.4
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	336.6	349.1
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | U.S. Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	336.6	349.1
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Foreign Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Maturities [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	127.2	117.8
Fair Value, Recurring [Member] | Level 1 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	708.3	823.5
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	3,296.1	3,698.7
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	3,179.5	3,277
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	252.9	225.8
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | U.S. Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	2.1	5.5
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Foreign Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	239.7	248.7
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	148.5	152.6
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,586.4	1,773
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	241.8	217
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	546.4	488.9
Fair Value, Recurring [Member] | Level 2 [Member] | Fixed Maturities [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	161.7	165.5
Fair Value, Recurring [Member] | Level 2 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 2 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	92.3	400.2
Fair Value, Recurring [Member] | Level 2 [Member] | Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	24.3	21.5
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	13.1	14
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	7.4	7.4
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | U.S. Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Foreign Governments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	7.4	7.4
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Fixed Maturities [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	5.7	6.6
Fair Value, Recurring [Member] | Level 3 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 0	$ 0
[1]	Derived from audited consolidated financial statements.

Investments - Schedule of Recon

Investments - Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3 (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 14	$ 10.4
Transfers into Level 3	0	3.5
Transfers out of Level 3	0	0
Included in net income	0	(2)
Included in other comprehensive income	(0.9)	0.6
Purchases	0	1.9
Issuances	0	0
Sales	0	(0.4)
Settlements	0	0
Ending balance	13.1	14
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at March 31, 2020	0	0
Credit-Financial [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	7.4	2.2
Transfers into Level 3	0	3.5
Transfers out of Level 3	0	0
Included in net income	0	(0.4)
Included in other comprehensive income	0	0.6
Purchases	0	1.9
Issuances	0	0
Sales	0	(0.4)
Settlements	0	0
Ending balance	7.4	7.4
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at March 31, 2020	0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6.6	8.2
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Included in net income	0	(1.6)
Included in other comprehensive income	(0.9)	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Ending balance	5.7	6.6
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at March 31, 2020	$ 0	$ 0

- Premiums Receivable (Details)

- Premiums Receivable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	[1]
Financing Receivable, Allowance for Credit Loss [Line Items]
Premiums receivable	$ 739.1	$ 688.2
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2020	7.9
Current period change for estimated uncollectible premiums	0.8
Write-offs of uncollectible premiums receivable	0
Balance, March 31, 2020	8.7
Cumulative Effect, Period Of Adoption, Adjustment
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2020	$ 0
[1]	Derived from audited consolidated financial statements.

- Reinsurance Recoverables (Det

- Reinsurance Recoverables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Reinsurance recoverables, net	$ 2,820.9	$ 3,104.6
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2020	1.1
Current period change for estimated uncollectible reinsurance	0
Write-offs of uncollectible reinsurance recoverables	0
Balance, March 31, 2020	$ 3.6
Percent rated A- or better	87.60%
Cumulative Effect, Period Of Adoption, Adjustment
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2020	$ 2.5

Reserves for Losses and Loss _3

Reserves for Losses and Loss Adjustment Expenses - Reserves for Losses and Loss Adjustment Expenses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	[1]
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves beginning of the year	$ 2,722.7	$ 2,562.9
Losses and LAE incurred during current calendar year, net of reinsurance:
Current accident year	278.2	240.4
Prior accident years	2.7	(2.5)
Losses and LAE incurred during calendar year, net of reinsurance	280.9	237.9
Losses and LAE payments made during current calendar year, net of reinsurance:
Current accident year	72.6	34.7
Prior accident years	263.8	221
Losses and LAE payments made during current calendar year, net of reinsurance:	336.4	255.7
Change in participation interest	32.5	(14.6)
Foreign exchange adjustments	(25.6)	(9.1)
Net reserves - end of period	2,674.1	2,521.4
Reinsurance recoverables on unpaid losses and LAE, end of period	2,393.5	2,147.5
Gross reserves - end of period	$ 5,067.6	$ 4,668.9	$ 5,157.6
[1]	Derived from audited consolidated financial statements.

Reserves for Losses and Loss _4

Reserves for Losses and Loss Adjustment Expenses - Impact from (Favorable) Unfavorable Development of Prior Accident Years' Loss and LAE Reserves on Each Reporting Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Net losses and adjustment expenses related to pandemic	$ 26.2
Total unfavorable (favorable) prior-year development	2.7	$ (2.5)
U.S. Operations [Member]
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	3.3	(4)
International Operations [Member]
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	(0.4)	0.8
Run Off Lines [Member]
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	$ (0.2)	$ 0.7

Disclosures about Fair Value _3

Disclosures about Fair Value of Financial Instruments - Summary of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Junior Subordinated Debentures [Member] | Trust Preferred Debentures [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	$ 172.7	$ 172.7
Junior Subordinated Debentures [Member] | Trust Preferred Debentures [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	173.6	174
Junior Subordinated Debentures [Member] | Junior Subordinated Debentures [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	84.8	84.7
Junior Subordinated Debentures [Member] | Junior Subordinated Debentures [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	92.3	92.5
Senior Unsecured Fixed Rate Notes [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	140	140
Senior Unsecured Fixed Rate Notes [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	125.9	144.2
Floating Rate Loan Stock [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	55	56.3
Floating Rate Loan Stock [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Instruments	$ 55.3	$ 56.8

Disclosures about Fair Value _4

Disclosures about Fair Value of Financial Instruments Disclosures about Fair Value of Financial Instruments - Summary of Fair Values Measured on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	$ 447.1
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	125.9
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	321.2
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0
Junior Subordinated Debentures [Member] | Trust Preferred Debentures [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	$ 0
Junior Subordinated Debentures [Member] | Trust Preferred Debentures [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	173.6	174
Junior Subordinated Debentures [Member] | Trust Preferred Debentures [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Junior Subordinated Debentures [Member] | Maybrooke Junior Subordinated Debentures [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Junior Subordinated Debentures [Member] | Maybrooke Junior Subordinated Debentures [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	92.3	92.5
Junior Subordinated Debentures [Member] | Maybrooke Junior Subordinated Debentures [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Senior Unsecured Fixed Rate Notes [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	125.9	144.2
Senior Unsecured Fixed Rate Notes [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Senior Unsecured Fixed Rate Notes [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Floating Rate Loan Stock [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	0	0
Floating Rate Loan Stock [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	55.3	56.8
Floating Rate Loan Stock [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments	$ 0	$ 0

Shareholders Equity - Additiona

Shareholders Equity - Additional Information (Detail) - USD ($)	Mar. 16, 2020	Feb. 18, 2020	Mar. 15, 2019	Feb. 20, 2019	Mar. 31, 2020	Mar. 31, 2019	May 03, 2016
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)		$ 0.31		$ 0.31	$ 0.31	$ 0.31
Cash dividends paid - common shares, total	$ 10,700,000		$ 10,800,000		$ 10,700,000	$ 10,800,000
2016 Repurchase Authorization [Member]
Class of Stock [Line Items]
Total number of shares authorized for purchase							$ 150,000,000
Remaining number of shares available under repurchase authorization					$ 53,300,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive (Loss) Income - Changes in Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019	Jan. 01, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,781.1	[1]	$ 1,746.7
Other comprehensive loss before reclassifications	(105.1)		47.9
Amounts reclassified from accumulated other comprehensive loss	(5.3)		2.6
Net current-period other comprehensive loss	(110.4)		50.5
Ending Balance	1,636.8		1,880.6
ASU 2016-13 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU 2016-13, net of taxes				$ (2.2)
Foreign Currency Translation Adjustments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(22.6)		(22.4)
Other comprehensive loss before reclassifications	(3.4)		0.2
Amounts reclassified from accumulated other comprehensive loss	0		0
Net current-period other comprehensive loss	(3.4)		0.2
Ending Balance	(26)		(22.2)
Foreign Currency Translation Adjustments [Member] | ASU 2016-13 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU 2016-13, net of taxes				0
Unrealized Holding Gains on Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	33.5		(49)
Other comprehensive loss before reclassifications	(101.7)		47.7
Amounts reclassified from accumulated other comprehensive loss	(5.3)		2.6
Net current-period other comprehensive loss	(107)		50.3
Ending Balance	(67.8)		1.3
Unrealized Holding Gains on Securities [Member] | ASU 2016-13 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU 2016-13, net of taxes				5.7
Defined Benefit Pension Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(8.1)		(6.7)
Other comprehensive loss before reclassifications	0		0
Amounts reclassified from accumulated other comprehensive loss	0		0
Net current-period other comprehensive loss	0		0
Ending Balance	(8.1)		(6.7)
Defined Benefit Pension Plans [Member] | ASU 2016-13 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU 2016-13, net of taxes				0
Accumulated Other Comprehensive Income (Loss) Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	2.8		(78.1)
Ending Balance	$ (101.9)		$ (27.6)
Accumulated Other Comprehensive Income (Loss) Member] | ASU 2016-13 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU 2016-13, net of taxes				$ 5.7
[1]	Derived from audited consolidated financial statements.

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive (Loss) Income - Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Unrealized gains and losses on securities:
Net of taxes	$ (5.3)	$ 2.6
Unrealized Gains and Losses on Securities [Member]
Unrealized gains and losses on securities:
Net realized investment (gains) loss	(3.4)	3.1
Benefit for income taxes	(1.9)	(0.5)
Net of taxes	$ (5.3)	$ 2.6

Net (Loss) Income Per Common _3

Net (Loss) Income Per Common Share - Net Income (Loss) Per Common Share on Basic and Diluted Basis (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (loss) income	$ (18.8)	$ 91.2
Weighted average common shares outstanding - basic (in shares)	34,469,516	33,984,329
Effect of dilutive securities:
Equity compensation awards (in shares)	0	753,610
Weighted average common shares outstanding - diluted (in shares)	34,469,516	34,737,939
Net (loss) income per common share:
Basic (in dollars per share)	$ (0.55)	$ 2.68
Diluted (in dollars per share)	$ (0.55)	$ 2.63

Net (Loss) Income Per Common _4

Net (Loss) Income Per Common Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Earnings Per Share [Abstract]
Treasury shares (in shares)	11,315,889	11,315,889	11,315,889
Equity compensation awards with anti-dilutive effect (in shares)	294,869	0

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Schedule of Interest Paid and Income Taxes Paid (Recovered) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow [Line Items]
Total interest paid	$ 7.9	$ 8.8
Income taxes paid	0.3	0.2
Income taxes recovered	0	0
Income taxes paid, net	0.3	0.2
Senior Unsecured Fixed Rate Notes [Member]
Supplemental Cash Flow [Line Items]
Total interest paid	2.3	2.3
Junior Subordinated Debentures [Member]
Supplemental Cash Flow [Line Items]
Total interest paid	3.7	4.1
Other Indebtedness [Member]
Supplemental Cash Flow [Line Items]
Total interest paid	$ 1.9	$ 2.4

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	May 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, compensation expense		$ 3,100,000	$ 3,700,000
Employee service share-based compensation, unrecognized compensation costs on non-vested awards		$ 14,700,000
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		1 year
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		4 years
Stock-Settled SARs Activity [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, compensation expense		$ 0	$ 400,000
Employee service share-based compensation, unrecognized compensation costs on non-vested awards		$ 0
2019 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized (in shares)	1,885,000
Expiration period	10 years

Share-based Compensation - Summ

Share-based Compensation - Summary of Restricted Share Activity (Detail) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Shares
Outstanding, beginning balance (in shares) | shares	471,271
Vested and issued (in shares) | shares	(134,983)
Expired or forfeited (in shares) | shares	(45,482)
Outstanding, ending balance (in shares) | shares	290,806
Weighted-Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 60.09
Vested and issued (in dollars per share) | $ / shares	55.87
Expired or forfeited (in dollars per share) | $ / shares	61.19
Outstanding, ending balance (in dollars per share) | $ / shares	$ 61.94

Share-based Compensation - Su_2

Share-based Compensation - Summary of SARs Activity (Detail) - Stock-Settled SARs Activity [Member]	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Shares
Outstanding, beginning balance (in shares) | shares	625,368
Exercised (in shares) | shares	(369,362)
Expired or forfeited (in shares) | shares	0
Outstanding, ending balance (in shares) | shares	256,006
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 33.60
Exercised (in dollars per share) | $ / shares	32.59
Expired or forfeited (in dollars per share) | $ / shares	0
Outstanding, ending balance (in dollars per share) | $ / shares	$ 35.05

Underwriting, Acquisition and_3

Underwriting, Acquisition and Insurance Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Underwriting Acquisition And Insurance Expenses [Abstract]
Commissions	$ 65.3	$ 63.3
General expenses	98.9	88.6
Premium taxes, boards and bureaus	8	8.3
Underwriting, acquisition and insurance expenses, total	172.2	160.2
Net deferral of policy acquisition costs	(4.2)	0
Total underwriting, acquisition and insurance expenses	168	160.2
Other corporate expenses	$ 3.3	$ 0.5	$ 3.3

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Net operating losses carryback period	2 years
Capital losses carryback period	3 years
Unrecognized tax benefits	$ 0	$ 0

Income Taxes - Schedule of Pre-

Income Taxes - Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (21.6)	$ 100.1
Effective Tax Rate	12.80%	8.90%
Bermuda [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (21.7)	$ 32
Effective Tax Rate	0.00%	0.00%
United States [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (10.7)	$ 69.4
Effective Tax Rate	55.00%	14.40%
United Kingdom [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 1.7	$ (3.5)
Effective Tax Rate	183.20%	31.50%
Belgium [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0
Effective Tax Rate	68.80%	30.80%
Brazil [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 2.2	$ 1.8
Effective Tax Rate	0.00%	0.00%
United Arab Emirates [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.9	$ 0.2
Effective Tax Rate	0.00%	0.00%
Ireland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0
Effective Tax Rate	0.00%	0.00%
Italy [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 3.4	$ (0.7)
Effective Tax Rate	0.00%	0.00%
Malta [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 2.6	$ 0.9
Effective Tax Rate	0.00%	0.00%
Luxembourg [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0
Effective Tax Rate	0.00%	0.00%
Switzerland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0
Effective Tax Rate	0.00%	0.00%

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at expected rate	$ 0.8	$ 14.9
Tax effect of:
Nontaxable investment income	(0.1)	(0.4)
Foreign exchange adjustments	(2)	0.5
Withholding taxes	0	0
Prior period adjustments	0	0
Change in valuation allowance	0	(0.6)
Other	(1.5)	(5.5)
Income tax (benefit) provision	$ (2.8)	$ 8.9

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments related to its limited partnership investments (up to)	$ 104.6
Contractual commitments period (not to exceed)	13 years

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	2
Assets associated with trade capital providers | $	$ 719.3	$ 916.3

Segment Information - Revenue a

Segment Information - Revenue and Income (Loss) Before Income Taxes for Each Segment (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Earned premiums	$ 435	$ 420.5
Net investment income	35.5	33.9
Fee and other income	2.1	2.3
Net realized investment (losses) gains	(36.1)	52.5
Foreign currency exchange gains (loss)	3	(0.7)
Other corporate expenses	(3.3)	(0.5)	$ (3.3)
Total revenue	436.5	509.2
Income (loss) before income taxes	(21.6)	100.1
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net investment income	0.5	0.3
Income (loss) before income taxes	(10.3)	(10.9)
U.S. Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums	302.5	273.8
Net investment income	25.2	23.1
Income (loss) before income taxes	36.9	42.9
International Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums	132.3	146.7
Net investment income	8.6	9.1
Income (loss) before income taxes	(12.3)	16.2
Run Off Lines [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums	0.2	0
Net investment income	1.2	1.4
Income (loss) before income taxes	$ 0.5	$ 0.6

Segment Information - Schedule

Segment Information - Schedule of Earned Premiums by Geographic Location (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 435	$ 420.5
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	299.7	272.6
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	86.7	97.1
Bermuda [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	21.2	16.6
Malta [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	11.8	20.8
Other Jurisdiction [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 15.6	$ 13.4

Segment Information - Identifia

Segment Information - Identifiable Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 10,201.3	$ 10,514.5	[1]
Operating Segments [Member] | U.S. Operations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	5,656.8	5,009
Operating Segments [Member] | International Operations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	3,991.3	5,002.4
Operating Segments [Member] | Run Off Lines [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	336.6	356.9
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 216.6	$ 146.2
[1]	Derived from audited consolidated financial statements.

Senior Unsecured Fixed Rate N_3

Senior Unsecured Fixed Rate Notes - Additional Information (Detail) - USD ($)	1 Months Ended
	Sep. 30, 2012	Mar. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Principal amount of senior note		$ 143,800,000	$ 143,800,000
Senior Unsecured Fixed Rate Notes [Member]
Schedule of Equity Method Investments [Line Items]
Principal amount of senior note	$ 143,750,000
Interest rate stated, percentage	6.50%
Redemption price, percentage	100.00%

Senior Unsecured Fixed Rate N_4

Senior Unsecured Fixed Rate Notes - Schedule Of Unamortized Debt Issuance Costs Deducted From Carrying Value Of Debt Liability (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Principal	$ 143.8	$ 143.8
Less: unamortized debt issuance costs	(3.8)	(3.8)
Senior unsecured fixed rate notes, less unamortized debt issuance costs	$ 140	$ 140	[1]
[1]	Derived from audited consolidated financial statements.

Senior Unsecured Fixed Rate N_5

Senior Unsecured Fixed Rate Notes - Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019		Mar. 31, 2019	Dec. 31, 2018
Assets
Investments	$ 4,811.4	$ 5,099.4	[1]
Cash	158.7	137.8	[1]
Accrued investment income	23.2	25.7	[1]
Premiums receivable	739.1	688.2	[1]
Reinsurance recoverables	2,820.9	3,104.6	[1]
Goodwill and other intangible assets, net	252.9	253.2
Deferred tax asset, net	44.5	6.1	[1]
Deferred acquisition costs, net	158	160.2	[1]
Ceded unearned premiums	652.9	545	[1]
Operating lease right-of-use assets	89.1	91.8	[1]
Other assets	435.4	387.1	[1]
Assets held for sale	15.2	15.4	[1]
Intercompany note receivable	0	0
Investments in subsidiaries	0	0
Total assets	10,201.3	10,514.5	[1]
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	5,067.6	5,157.6	[1]	$ 4,668.9
Unearned premiums	1,460	1,410.9	[1]
Funds held and ceded reinsurance payable, net	1,154.8	1,253.7
Debt	577.5	578.7
Current income taxes payable, net	17.7	0.8	[1]
Accrued underwriting expenses and other liabilities	185.3	226	[1]
Operating lease liabilities	101.6	105.7	[1]
Due to (from) affiliates	0	0
Total liabilities	8,564.5	8,733.4	[1]
Total shareholders' equity	1,636.8	1,781.1	[1]	$ 1,880.6	$ 1,746.7
Total liabilities and shareholders' equity	10,201.3	10,514.5	[1]
Consolidating Adjustments [Member]
Assets
Investments	0	0
Cash	0	0
Accrued investment income	0	0
Premiums receivable	0	0
Reinsurance recoverables	0	0
Goodwill and other intangible assets, net	0	0
Deferred tax asset, net	0	0
Deferred acquisition costs, net	0	0
Ceded unearned premiums	0	0
Operating lease right-of-use assets	0	0
Other assets	0	0
Assets held for sale	0	0
Intercompany note receivable	0	0
Investments in subsidiaries	(1,796.7)	(1,916.7)
Total assets	(1,796.7)	(1,916.7)
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	0	0
Unearned premiums	0	0
Funds held and ceded reinsurance payable, net	0	0
Debt	0	0
Current income taxes payable, net	0	0
Accrued underwriting expenses and other liabilities	0	0
Operating lease liabilities	0	0
Due to (from) affiliates	(57.9)	(19.3)
Total liabilities	(57.9)	(19.3)
Total shareholders' equity	(1,738.8)	(1,897.4)
Total liabilities and shareholders' equity	(1,796.7)	(1,916.7)
Other Subsidiaries and Eliminations [Member]
Assets
Investments	1,487.8	1,693.2
Cash	116.5	104.3
Accrued investment income	6.5	7.5
Premiums receivable	474.7	456.9
Reinsurance recoverables	1,096	1,415.2
Goodwill and other intangible assets, net	89.2	89.2
Deferred tax asset, net	4.4	5.7
Deferred acquisition costs, net	71.7	71.8
Ceded unearned premiums	316.7	238.6
Operating lease right-of-use assets	24.5	25.1
Other assets	264.2	213.5
Assets held for sale	0	0
Intercompany note receivable	(57.4)	(56.7)
Investments in subsidiaries	0	0
Total assets	3,894.8	4,264.3
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	1,939.6	2,120.1
Unearned premiums	562.9	511.1
Funds held and ceded reinsurance payable, net	463.1	607.8
Debt	139.8	141
Current income taxes payable, net	(5.4)	(7.4)
Accrued underwriting expenses and other liabilities	101.9	124.8
Operating lease liabilities	27.8	29.5
Due to (from) affiliates	25.6	13.4
Total liabilities	3,255.3	3,540.3
Total shareholders' equity	639.5	724
Total liabilities and shareholders' equity	3,894.8	4,264.3
Argo Group International Holdings, Ltd (Parent Guarantor) [Member]
Assets
Investments	0.3	0.6
Cash	1.8	1.9
Accrued investment income	0	0
Premiums receivable	0	0
Reinsurance recoverables	0	0
Goodwill and other intangible assets, net	40.3	40.6
Deferred tax asset, net	0	0
Deferred acquisition costs, net	0	0
Ceded unearned premiums	0	0
Operating lease right-of-use assets	7.1	7.1
Other assets	18.4	7.8
Assets held for sale	0	0
Intercompany note receivable	0	0
Investments in subsidiaries	1,796.7	1,916.7
Total assets	1,864.6	1,974.7
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	0	0
Unearned premiums	0	0
Funds held and ceded reinsurance payable, net	0	0
Debt	153.4	153.4
Current income taxes payable, net	0	0
Accrued underwriting expenses and other liabilities	9.2	13.6
Operating lease liabilities	7.3	7.3
Due to (from) affiliates	57.9	19.3
Total liabilities	227.8	193.6
Total shareholders' equity	1,636.8	1,781.1
Total liabilities and shareholders' equity	1,864.6	1,974.7
Argo Group US, Inc. and Subsidiaries (Subsidiary Issuer) [Member]
Assets
Investments	3,323.3	3,405.6
Cash	40.4	31.6
Accrued investment income	16.7	18.2
Premiums receivable	264.4	231.3
Reinsurance recoverables	1,724.9	1,689.4
Goodwill and other intangible assets, net	123.4	123.4
Deferred tax asset, net	40.1	0.4
Deferred acquisition costs, net	86.3	88.4
Ceded unearned premiums	336.2	306.4
Operating lease right-of-use assets	57.5	59.6
Other assets	152.8	165.8
Assets held for sale	15.2	15.4
Intercompany note receivable	57.4	56.7
Investments in subsidiaries	0	0
Total assets	6,238.6	6,192.2
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	3,128	3,037.5
Unearned premiums	897.1	899.8
Funds held and ceded reinsurance payable, net	691.7	645.9
Debt	284.3	284.3
Current income taxes payable, net	23.1	8.2
Accrued underwriting expenses and other liabilities	74.2	87.6
Operating lease liabilities	66.5	68.9
Due to (from) affiliates	(25.6)	(13.4)
Total liabilities	5,139.3	5,018.8
Total shareholders' equity	1,099.3	1,173.4
Total liabilities and shareholders' equity	$ 6,238.6	$ 6,192.2
[1]	Derived from audited consolidated financial statements.

Senior Unsecured Fixed Rate N_6

Senior Unsecured Fixed Rate Notes - Condensed Consolidating Statement of (Loss) Income (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Premiums and other revenue:
Earned premiums	$ 435	$ 420.5
Net investment (expense) income	35.5	33.9
Fee and other income	2.1	2.3
Net realized investment (losses) gains before income taxes	(36.1)	52.5
Total revenue	436.5	509.2
Expenses:
Losses and loss adjustment expenses	280.9	237.9
Underwriting, acquisition and insurance expenses	168	160.2
Other corporate expenses	3.3	0.5	$ 3.3
Interest expense	7.7	8.5
Fee and other expense	1.2	1.3
Foreign currency exchange (gains) loss	(3)	0.7
Total expenses	458.1	409.1
(Loss) income before income taxes	(21.6)	100.1
Income tax (benefit) provision	(2.8)	8.9
Net (loss) income before equity in earnings of subsidiaries	(18.8)	91.2
Equity in undistributed earnings of subsidiaries	0	0
Net (loss) income	(18.8)	91.2
Consolidating Adjustments [Member]
Premiums and other revenue:
Earned premiums	0	0
Net investment (expense) income	0	0
Fee and other income	0	0
Net realized investment (losses) gains before income taxes	0	0
Total revenue	0	0
Expenses:
Losses and loss adjustment expenses	0	0
Underwriting, acquisition and insurance expenses	0	0
Other corporate expenses	0	0
Interest expense	0	0
Fee and other expense	0	0
Foreign currency exchange (gains) loss	0	0
Total expenses	0	0
(Loss) income before income taxes	0	0
Income tax (benefit) provision	0	0
Net (loss) income before equity in earnings of subsidiaries	0	0
Equity in undistributed earnings of subsidiaries	8.9	(94.4)
Net (loss) income	8.9	(94.4)
Other Subsidiaries and Eliminations [Member]
Premiums and other revenue:
Earned premiums	133.5	154
Net investment (expense) income	10.9	10.8
Fee and other income	1.3	1.2
Net realized investment (losses) gains before income taxes	4.6	6.7
Total revenue	150.3	172.7
Expenses:
Losses and loss adjustment expenses	90.4	79.9
Underwriting, acquisition and insurance expenses	60.4	55.9
Other corporate expenses	0	0
Interest expense	2	2.1
Fee and other expense	0.5	0.5
Foreign currency exchange (gains) loss	(2)	0.4
Total expenses	151.3	138.8
(Loss) income before income taxes	(1)	33.9
Income tax (benefit) provision	3.1	(1.1)
Net (loss) income before equity in earnings of subsidiaries	(4.1)	35
Equity in undistributed earnings of subsidiaries	0	0
Net (loss) income	(4.1)	35
Argo Group International Holdings, Ltd (Parent Guarantor) [Member]
Premiums and other revenue:
Earned premiums	0	0
Net investment (expense) income	0	(0.7)
Fee and other income	0	0
Net realized investment (losses) gains before income taxes	(0.1)	(0.1)
Total revenue	(0.1)	(0.8)
Expenses:
Losses and loss adjustment expenses	0	0
Underwriting, acquisition and insurance expenses	5.8	0.2
Other corporate expenses	2.6	0.5
Interest expense	1.4	1.7
Fee and other expense	0	0
Foreign currency exchange (gains) loss	0	0
Total expenses	9.8	2.4
(Loss) income before income taxes	(9.9)	(3.2)
Income tax (benefit) provision	0	0
Net (loss) income before equity in earnings of subsidiaries	(9.9)	(3.2)
Equity in undistributed earnings of subsidiaries	(8.9)	94.4
Net (loss) income	(18.8)	91.2
Argo Group US, Inc. and Subsidiaries (Subsidiary Issuer) [Member]
Premiums and other revenue:
Earned premiums	301.5	266.5
Net investment (expense) income	24.6	23.8
Fee and other income	0.8	1.1
Net realized investment (losses) gains before income taxes	(40.6)	45.9
Total revenue	286.3	337.3
Expenses:
Losses and loss adjustment expenses	190.5	158
Underwriting, acquisition and insurance expenses	101.8	104.1
Other corporate expenses	0.7	0
Interest expense	4.3	4.7
Fee and other expense	0.7	0.8
Foreign currency exchange (gains) loss	(1)	0.3
Total expenses	297	267.9
(Loss) income before income taxes	(10.7)	69.4
Income tax (benefit) provision	(5.9)	10
Net (loss) income before equity in earnings of subsidiaries	(4.8)	59.4
Equity in undistributed earnings of subsidiaries	0	0
Net (loss) income	$ (4.8)	$ 59.4

Senior Unsecured Fixed Rate N_7

Senior Unsecured Fixed Rate Notes - Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	$ (31.4)	$ 55.6
Cash flows from investing activities:
Proceeds from sales of investments	638.1	272.5
Maturities and mandatory calls of fixed maturity investments	158.2	65.8
Purchases of investments	(849.2)	(384.2)
Change in short-term investments and foreign regulatory deposits	116.2	38
Settlements of foreign currency exchange forward contracts	3.1	3.6
Purchases of fixed assets and other, net	(5.1)	(27.4)
Cash provided by (used in) investing activities	61.3	(31.7)
Cash flows from financing activities:
Payment on the intercompany note		0
Activity under stock incentive plans	0.3	0.3
Payment of cash dividends to common shareholders	(10.7)	(10.8)
Cash used in financing activities	(10.4)	(10.5)
Effect of exchange rate changes on cash	1.4	0.1
Change in cash	20.9	13.5
Cash, beginning of year	137.8	139.2
Cash, end of period	158.7	152.7
Argo Group International Holdings, Ltd (Parent Guarantor) [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	10	8.8
Cash flows from investing activities:
Proceeds from sales of investments	0	0
Maturities and mandatory calls of fixed maturity investments	0	0
Purchases of investments	0	0
Change in short-term investments and foreign regulatory deposits	0.3	1.9
Settlements of foreign currency exchange forward contracts	0	0
Purchases of fixed assets and other, net	0	0
Cash provided by (used in) investing activities	0.3	1.9
Cash flows from financing activities:
Payment on the intercompany note		0
Activity under stock incentive plans	0.3	0.3
Payment of cash dividends to common shareholders	(10.7)	(10.8)
Cash used in financing activities	(10.4)	(10.5)
Effect of exchange rate changes on cash	0	0
Change in cash	(0.1)	0.2
Cash, beginning of year	1.9	1.7
Cash, end of period	1.8	1.9
Argo Group US, Inc. and Subsidiaries (Subsidiary Issuer) [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	35.7	29.5
Cash flows from investing activities:
Proceeds from sales of investments	309.4	156.6
Maturities and mandatory calls of fixed maturity investments	100.5	51.3
Purchases of investments	(583)	(249)
Change in short-term investments and foreign regulatory deposits	128.8	35.3
Settlements of foreign currency exchange forward contracts	0	0.3
Purchases of fixed assets and other, net	17.4	(3.3)
Cash provided by (used in) investing activities	(26.9)	(8.8)
Cash flows from financing activities:
Payment on the intercompany note		19.1
Activity under stock incentive plans	0	0
Payment of cash dividends to common shareholders	0	0
Cash used in financing activities	0	(19.1)
Effect of exchange rate changes on cash	0	0
Change in cash	8.8	1.6
Cash, beginning of year	31.6	31.7
Cash, end of period	40.4	33.3
Other Subsidiaries and Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	(77.1)	17.3
Cash flows from investing activities:
Proceeds from sales of investments	328.7	115.9
Maturities and mandatory calls of fixed maturity investments	57.7	14.5
Purchases of investments	(266.2)	(135.2)
Change in short-term investments and foreign regulatory deposits	(12.9)	0.8
Settlements of foreign currency exchange forward contracts	3.1	3.3
Purchases of fixed assets and other, net	(22.5)	(24.1)
Cash provided by (used in) investing activities	87.9	(24.8)
Cash flows from financing activities:
Payment on the intercompany note		(19.1)
Activity under stock incentive plans	0	0
Payment of cash dividends to common shareholders	0	0
Cash used in financing activities	0	19.1
Effect of exchange rate changes on cash	1.4	0.1
Change in cash	12.2	11.7
Cash, beginning of year	104.3	105.8
Cash, end of period	116.5	117.5
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	0	0
Cash flows from investing activities:
Proceeds from sales of investments	0	0
Maturities and mandatory calls of fixed maturity investments	0	0
Purchases of investments	0	0
Change in short-term investments and foreign regulatory deposits	0	0
Settlements of foreign currency exchange forward contracts	0	0
Purchases of fixed assets and other, net	0	0
Cash provided by (used in) investing activities	0	0
Cash flows from financing activities:
Payment on the intercompany note		0
Activity under stock incentive plans	0	0
Payment of cash dividends to common shareholders	0	0
Cash used in financing activities	0	0
Effect of exchange rate changes on cash	0	0
Change in cash	0	0
Cash, beginning of year	0	0
Cash, end of period	$ 0	$ 0

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ in Millions	Apr. 30, 2020	Jun. 30, 2020
Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from divestiture of businesses	$ 38
Forecast [Member]
Subsequent Event [Line Items]
Gain on disposition of business		$ 32