Reserves for Losses and Loss Adjustment Expenses - Summary of Information about Incurred and Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance (Detail) $ in Millions	Dec. 31, 2022 USD ($) claim	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	$ 2,163.0
U.S. Operations | Liability
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	3,613.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	2,449.7
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	56.5
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	1,219.8
U.S. Operations | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	334.3	$ 357.3	$ 344.8	$ 343.1	$ 346.6	$ 351.5	$ 360.4	$ 361.0	$ 355.8	$ 344.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	329.3	325.4	318.2	306.9	289.3	266.5	228.8	174.3	109.7	36.5
IBNR & Expected Development on Reported Claims	$ 0.4
Cumulative number of reported claims | claim	22,317
U.S. Operations | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 310.7	341.3	327.4	321.9	323.9	326.3	330.0	337.1	328.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	304.4	291.4	283.2	266.3	240.6	206.9	154.6	91.0	32.4
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	22,254
U.S. Operations | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 318.9	347.9	335.4	328.0	328.7	330.3	343.8	339.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	305.6	289.3	263.9	236.4	195.6	140.2	86.9	33.7
IBNR & Expected Development on Reported Claims	$ 6.5
Cumulative number of reported claims | claim	20,874
U.S. Operations | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 349.1	379.0	355.3	353.0	342.4	350.5	342.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	327.1	293.8	255.6	217.1	144.1	84.5	28.5
IBNR & Expected Development on Reported Claims	$ 11.5
Cumulative number of reported claims | claim	17,947
U.S. Operations | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 385.2	431.7	397.7	384.3	373.7	374.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	348.0	295.2	238.5	158.8	83.0	27.8
IBNR & Expected Development on Reported Claims	$ 22.7
Cumulative number of reported claims | claim	20,419
U.S. Operations | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 366.5	420.4	414.5	430.4	426.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	315.9	245.5	175.8	98.9	34.3
IBNR & Expected Development on Reported Claims	$ 21.8
Cumulative number of reported claims | claim	22,925
U.S. Operations | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 318.6	427.1	423.7	421.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	260.1	186.1	113.6	32.4
IBNR & Expected Development on Reported Claims	$ 21.1
Cumulative number of reported claims | claim	22,161
U.S. Operations | Liability | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 371.1	386.7	404.2
Cumulative Paid Losses & ALAE, Net of Reinsurance	149.0	85.9	25.6
IBNR & Expected Development on Reported Claims	$ 136.0
Cumulative number of reported claims | claim	17,452
U.S. Operations | Liability | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 419.1	416.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	83.1	27.5
IBNR & Expected Development on Reported Claims	$ 253.5
Cumulative number of reported claims | claim	13,367
U.S. Operations | Liability | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 439.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	27.2
IBNR & Expected Development on Reported Claims	$ 354.3
Cumulative number of reported claims | claim	11,011
U.S. Operations | Professional
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 868.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	493.9
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	(3.0)
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	371.2
U.S. Operations | Professional | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	17.9	18.0	18.1	18.3	19.5	19.8	19.0	21.1	21.5	20.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	17.9	17.9	17.9	17.9	17.5	17.6	14.2	10.9	6.3	1.9
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	625
U.S. Operations | Professional | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 32.7	34.4	35.1	35.4	36.2	33.7	26.0	22.4	22.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	33.5	33.6	33.3	32.3	25.5	24.1	15.1	5.4	2.3
IBNR & Expected Development on Reported Claims	$ (0.8)
Cumulative number of reported claims | claim	1,044
U.S. Operations | Professional | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 31.3	38.3	37.9	37.1	34.0	33.2	29.5	29.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	33.8	31.7	31.3	26.2	20.8	15.6	8.3	1.8
IBNR & Expected Development on Reported Claims	$ (2.5)
Cumulative number of reported claims | claim	1,832
U.S. Operations | Professional | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 43.5	43.0	35.5	42.9	45.1	44.8	44.2
Cumulative Paid Losses & ALAE, Net of Reinsurance	38.3	34.4	30.8	28.9	24.6	11.9	2.4
IBNR & Expected Development on Reported Claims	$ 2.4
Cumulative number of reported claims | claim	3,263
U.S. Operations | Professional | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 87.0	99.5	87.9	78.3	61.8	60.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	85.5	77.9	59.7	38.0	24.9	3.5
IBNR & Expected Development on Reported Claims	$ 1.7
Cumulative number of reported claims | claim	3,772
U.S. Operations | Professional | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 88.5	94.8	79.2	73.2	70.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	78.8	62.6	43.8	16.7	4.5
IBNR & Expected Development on Reported Claims	$ 8.8
Cumulative number of reported claims | claim	4,328
U.S. Operations | Professional | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 94.5	105.0	96.8	94.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	81.7	50.0	32.9	4.9
IBNR & Expected Development on Reported Claims	$ 9.5
Cumulative number of reported claims | claim	5,133
U.S. Operations | Professional | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 127.8	142.6	152.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	70.5	36.4	13.3
IBNR & Expected Development on Reported Claims	$ 29.6
Cumulative number of reported claims | claim	5,476
U.S. Operations | Professional | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 159.5	177.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	39.6	12.2
IBNR & Expected Development on Reported Claims	$ 97.4
Cumulative number of reported claims | claim	5,895
U.S. Operations | Professional | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 185.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	14.3
IBNR & Expected Development on Reported Claims	$ 163.2
Cumulative number of reported claims | claim	4,864
U.S. Operations | Specialty
Claims Development [Line Items]
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	$ 45.3
U.S. Operations | Property
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	924.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	858.6
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	(5.5)
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	60.2
U.S. Operations | Property | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	76.9	77.2	78.2	78.4	78.2	77.8	78.2	78.7	79.9	74.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	76.9	77.2	78.2	78.1	75.9	77.1	77.4	75.5	73.2	52.5
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	9,707
U.S. Operations | Property | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 76.1	76.0	76.1	76.9	76.9	77.1	77.0	82.2	80.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	76.0	76.0	76.1	76.4	76.3	76.4	75.7	73.1	51.6
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	8,034
U.S. Operations | Property | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 68.4	69.2	69.2	69.1	68.9	69.9	73.4	74.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	68.6	69.0	68.5	68.3	67.9	68.6	67.6	44.6
IBNR & Expected Development on Reported Claims	$ (0.1)
Cumulative number of reported claims | claim	7,341
U.S. Operations | Property | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 54.2	56.5	56.6	56.6	57.1	57.6	59.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	54.5	56.3	56.4	56.1	55.8	55.2	39.4
IBNR & Expected Development on Reported Claims	$ (0.2)
Cumulative number of reported claims | claim	7,687
U.S. Operations | Property | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 97.4	94.5	94.9	86.9	79.6	75.2
Cumulative Paid Losses & ALAE, Net of Reinsurance	95.1	88.4	100.8	113.9	95.3	54.4
IBNR & Expected Development on Reported Claims	$ (1.3)
Cumulative number of reported claims | claim	9,913
U.S. Operations | Property | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 102.4	96.9	95.1	93.1	89.2
Cumulative Paid Losses & ALAE, Net of Reinsurance	101.4	98.8	107.0	126.7	61.3
IBNR & Expected Development on Reported Claims	$ (2.4)
Cumulative number of reported claims | claim	10,868
U.S. Operations | Property | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 97.9	98.4	88.8	91.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	94.0	90.9	82.4	55.8
IBNR & Expected Development on Reported Claims	$ 1.9
Cumulative number of reported claims | claim	11,481
U.S. Operations | Property | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 133.1	133.2	129.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	121.6	116.6	75.9
IBNR & Expected Development on Reported Claims	$ (7.3)
Cumulative number of reported claims | claim	11,356
U.S. Operations | Property | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 114.8	111.7
Cumulative Paid Losses & ALAE, Net of Reinsurance	118.3	71.3
IBNR & Expected Development on Reported Claims	$ (14.5)
Cumulative number of reported claims | claim	10,255
U.S. Operations | Property | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 103.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	52.2
IBNR & Expected Development on Reported Claims	$ 22.8
Cumulative number of reported claims | claim	7,960
U.S. Operations | Specialty Admitted | Specialty
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 72.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	28.1
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	0.8
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	45.3
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	0.9	0.9	0.9	0.9	0.9	1.7	2.5	4.6	8.6	10.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.4
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	28
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 4.1	4.1	4.6	4.6	4.8	6.0	8.9	13.1	13.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	4.1	4.1	4.0	4.1	4.1	4.0	4.0	3.3	1.1
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	20
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 0.2	0.3	0.5	1.2	5.5	9.5	14.3	14.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.2	0.3	0.3	0.3	0.3	0.2	0.1	0.2
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	14
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 3.2	3.3	4.7	6.2	11.2	15.0	15.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	2.8	2.8	2.2	2.2	2.2	1.6	1.3
IBNR & Expected Development on Reported Claims	$ 0.4
Cumulative number of reported claims | claim	46
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 0.7	0.7	0.9	7.6	16.2	16.2
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.2	0.2	0.1	0.0	0.1	0.3
IBNR & Expected Development on Reported Claims	$ 0.5
Cumulative number of reported claims | claim	62
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 3.5	3.5	3.3	17.4	20.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	2.4	1.2	1.7	0.7	0.0
IBNR & Expected Development on Reported Claims	$ 0.1
Cumulative number of reported claims | claim	82
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 5.9	5.6	8.5	22.7
Cumulative Paid Losses & ALAE, Net of Reinsurance	5.4	3.2	0.7	0.7
IBNR & Expected Development on Reported Claims	$ 0.4
Cumulative number of reported claims | claim	124
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 15.9	10.3	25.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	10.6	7.6	0.3
IBNR & Expected Development on Reported Claims	$ 0.7
Cumulative number of reported claims | claim	273
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 5.2	27.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	1.4	0.2
IBNR & Expected Development on Reported Claims	$ 3.7
Cumulative number of reported claims | claim	290
U.S. Operations | Specialty Admitted | Specialty | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 33.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.1
IBNR & Expected Development on Reported Claims	$ 25.7
Cumulative number of reported claims | claim	236
International Operations | Argo Insurance Bermuda- Liability | Liability
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 175.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	97.2
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	0.5
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	78.8
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	5.8	6.0	5.3	5.3	2.2	4.9	8.5	8.5	8.5	8.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	3.7	2.4	2.4	2.3	2.3	2.3	0.0	0.0	0.0	0.0
IBNR & Expected Development on Reported Claims	$ 0.2
Cumulative number of reported claims | claim	1,210
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 1.6	1.6	2.3	2.3	1.5	6.2	9.8	9.8	9.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	1.4	1.4	1.4	1.2	1.2	0.1	0.1	0.0	0.0
IBNR & Expected Development on Reported Claims	$ (0.4)
Cumulative number of reported claims | claim	1,360
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 50.3	51.3	45.1	45.4	35.4	24.8	14.3	11.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	50.2	38.9	34.8	26.6	20.3	16.1	0.0	0.0
IBNR & Expected Development on Reported Claims	$ 0.0
Cumulative number of reported claims | claim	1,623
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 2.4	0.8	6.1	6.6	14.0	14.0	13.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.3	0.2	0.1	0.1	0.0	0.0	0.0
IBNR & Expected Development on Reported Claims	$ 2.0
Cumulative number of reported claims | claim	1,987
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 44.3	37.3	30.3	26.9	17.3	17.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	22.0	19.7	18.0	3.4	3.3	0.0
IBNR & Expected Development on Reported Claims	$ 7.8
Cumulative number of reported claims | claim	2,114
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 22.9	24.2	26.6	32.1	8.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	18.5	18.5	18.3	13.8	0.0
IBNR & Expected Development on Reported Claims	$ 3.5
Cumulative number of reported claims | claim	1,140
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 13.3	13.8	13.6	13.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.6	0.7	0.1	0.0
IBNR & Expected Development on Reported Claims	$ 12.1
Cumulative number of reported claims | claim	1,179
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 12.4	24.9	23.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.5	7.0	0.8
IBNR & Expected Development on Reported Claims	$ 11.9
Cumulative number of reported claims | claim	1,336
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 11.4	12.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0	0.0
IBNR & Expected Development on Reported Claims	$ 10.2
Cumulative number of reported claims | claim	1,252
International Operations | Argo Insurance Bermuda- Liability | Liability | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 11.1
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0
IBNR & Expected Development on Reported Claims	$ 11.1
Cumulative number of reported claims | claim	875
International Operations | Argo Insurance Bermuda- Liability | Professional
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 106.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	19.8
Other Property outstanding liabilities including unpaid loss and ALAE prior to 2013, net of reinsurance	0.3
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance	86.9
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2013
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	3.5	1.0	0.0	0.0	0.0	1.8	3.1	3.8	3.8	3.8
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 3.4
Cumulative number of reported claims | claim	1,081
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2014
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 10.1	8.1	12.5	10.2	3.9	4.0	4.0	4.0	4.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.4	0.4	3.2	0.4	1.0	0.3	0.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 2.3
Cumulative number of reported claims | claim	1,142
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2015
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 7.9	7.3	5.2	5.0	2.7	4.9	4.9	4.9
Cumulative Paid Losses & ALAE, Net of Reinsurance	2.9	2.9	0.0	0.0	0.0	0.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 3.5
Cumulative number of reported claims | claim	1,197
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2016
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 1.9	3.1	7.3	3.1	4.8	6.7	6.7
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0	0.0	0.0	0.0	0.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 1.8
Cumulative number of reported claims | claim	1,293
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2017
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 10.5	12.4	9.5	9.7	7.6	7.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	9.8	9.8	9.8	4.9	0.1	$ 0.1
IBNR & Expected Development on Reported Claims	$ 0.7
Cumulative number of reported claims | claim	1,357
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2018
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 21.3	6.5	8.0	8.3	8.3
Cumulative Paid Losses & ALAE, Net of Reinsurance	6.0	2.1	2.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 9.9
Cumulative number of reported claims | claim	1,138
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2019
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 18.3	16.4	8.7	9.6
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.7	0.6	0.6	$ 2.0
IBNR & Expected Development on Reported Claims	$ 7.6
Cumulative number of reported claims | claim	843
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2020
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 10.4	10.4	10.4
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 10.3
Cumulative number of reported claims | claim	908
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2021
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 13.0	13.0
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0	$ 0.0
IBNR & Expected Development on Reported Claims	$ 13.0
Cumulative number of reported claims | claim	822
International Operations | Argo Insurance Bermuda- Liability | Professional | Accident Year 2022
Claims Development [Line Items]
Incurred Losses & ALAE, Net of Reinsurance	$ 9.5
Cumulative Paid Losses & ALAE, Net of Reinsurance	0.0
IBNR & Expected Development on Reported Claims	$ 9.5
Cumulative number of reported claims | claim	597