Unpaid Loss and Loss Adjustment Expense - Claims Development Information, Incurred Losses (Details) $ in Millions	Dec. 31, 2025 USD ($) claim segment	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 718.3
IBNR	$ 64.6
Cumulative Number of Reported Claims | claim	369,633
Accident amount (less than)	$ 0.1	$ 0.1	$ 0.1	$ 0.1	$ 0.1	$ 0.1	$ 0.1		$ 0.1	$ 0.1
IBNR, net of reinsurance (less than)	0.1				0.1	0.1	0.1		0.1	0.1
Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	285.8
IBNR	$ 6.2
Cumulative Number of Reported Claims | claim	2,764,894
Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 491.0
IBNR	$ 40.5
Cumulative Number of Reported Claims | claim	346,498
2016 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 0.0	0.0	0.0	0.0	0.0	0.0	0.0	$ 0.0	0.0	0.0
IBNR	$ 0.0
Cumulative Number of Reported Claims | segment	8
2016 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 3.3	3.3	3.4	2.0	1.8	1.7	1.7	1.7	2.0	$ 1.6
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	1,628
2017 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 1.7	1.6	1.7	1.7	1.7	1.7	1.7	1.7	1.7
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	1,759
2017 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 38.3	38.1	38.0	32.5	32.3	31.4	30.2	30.0	$ 28.6
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	29,056
2018 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 13.4	13.4	13.4	13.4	13.4	13.4	13.5	15.0
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	10,534
2018 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 41.8	42.1	38.6	33.9	31.8	31.9	29.7	$ 31.4
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	44,104
2019 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 46.2	46.2	46.1	46.3	46.3	46.1	46.0
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	19,512
2019 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 31.3	31.6	33.2	24.6	23.2	24.9	$ 24.2
IBNR	$ 0.2
Cumulative Number of Reported Claims | claim	51,136
2020 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 52.6	52.4	52.4	51.5	51.5	53.0
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	30,372
2020 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 0.7	0.7	0.6	1.0	0.6	0.7
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	20,922
2020 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 14.8	15.4	16.7	11.8	12.0	$ 10.8
IBNR	$ 0.3
Cumulative Number of Reported Claims | claim	37,326
2021 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 58.6	58.6	58.4	55.9	59.4
IBNR	$ 0.2
Cumulative Number of Reported Claims | claim	53,560
2021 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 9.5	9.5	9.5	9.7	10.0
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	197,014
2021 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 82.9	84.7	86.8	75.3	$ 75.3
IBNR	$ 0.8
Cumulative Number of Reported Claims | claim	43,119
2022 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 94.0	93.8	92.6	96.5
IBNR	$ 1.4
Cumulative Number of Reported Claims | claim	56,105
2022 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 25.1	25.2	25.3	27.4
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	375,674
2022 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 89.5	92.3	92.0	$ 83.1
IBNR	$ 3.1
Cumulative Number of Reported Claims | claim	46,802
2023 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 133.6	136.5	143.2
IBNR	$ 3.0
Cumulative Number of Reported Claims | claim	60,868
2023 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 49.0	48.9	51.9
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	510,111
2023 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 65.5	81.1	$ 79.1
IBNR	$ 3.4
Cumulative Number of Reported Claims | claim	39,211
2024 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 138.9	154.7
IBNR	$ 9.0
Cumulative Number of Reported Claims | claim	68,389
2024 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 71.8	72.3
IBNR	$ 0.0
Cumulative Number of Reported Claims | claim	697,403
2024 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 60.5	$ 51.2
IBNR	$ 8.6
Cumulative Number of Reported Claims | claim	28,193
2025 | Home and renters
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 179.3
IBNR	$ 51.0
Cumulative Number of Reported Claims | claim	68,526
2025 | Pet
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 129.7
IBNR	$ 6.2
Cumulative Number of Reported Claims | claim	963,770
2025 | Car
Claims Development [Line Items]
Total incurred losses and ALAE, net	$ 63.1
IBNR	$ 24.1
Cumulative Number of Reported Claims | claim	25,923