Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues
Premiums	$ 1,331.2	$ 1,186.0	$ 3,888.8	$ 3,527.6
Net investment income	73.0	78.8	220.4	231.2
Net realized and unrealized investment gains (losses):
Net realized gains (losses) from sales and other	(0.1)	3.6	(16.3)	6.8
Net change in fair value of equity securities	(29.1)	0.3	(106.1)	65.9
Recoveries (Impairments) on Investments:
Credit-related recoveries (impairments)	(1.4)	0.7	(1.5)	0.6
Losses on intent to sell securities	(14.3)	(0.6)	(14.8)	(0.7)
Recoveries (impairments) on investments	(15.7)	0.1	(16.3)	(0.1)
Total net realized and unrealized investment gains (losses)	(44.9)	4.0	(138.7)	72.6
Fees and other income	7.0	6.1	19.4	17.9
Total revenues	1,366.3	1,274.9	3,989.9	3,849.3
Losses and expenses
Losses and loss adjustment expenses	939.6	844.0	2,572.6	2,370.4
Amortization of deferred acquisition costs	277.1	244.0	809.3	728.5
Interest expense	8.5	8.5	25.5	25.5
Other operating expenses	140.6	135.9	423.8	408.4
Total losses and expenses	1,365.8	1,232.4	3,831.2	3,532.8
Income from continuing operations before income taxes	0.5	42.5	158.7	316.5
Income tax expense (benefit):
Current	12.9	9.9	72.5	47.1
Deferred	(13.0)	(2.2)	(42.5)	12.2
Total income tax expense (benefit)	(0.1)	7.7	30.0	59.3
Income from continuing operations	0.6	34.8	128.7	257.2
Discontinued operations (net of taxes):
Net income	$ 0.2	$ 34.0	$ 127.6	$ 255.2
Basic:
Income from continuing operations	$ 0.02	$ 0.98	$ 3.62	$ 7.14
Net income per share	$ 0.01	$ 0.95	$ 3.59	$ 7.09
Weighted average shares outstanding	35.6	35.7	35.6	36.0
Diluted:
Income from continuing operations	$ 0.02	$ 0.96	$ 3.56	$ 7.04
Net income per share	$ 0.01	$ 0.94	$ 3.53	$ 6.98
Weighted average shares outstanding	36.1	36.3	36.1	36.6
Life [Member]
Discontinued operations (net of taxes):
Loss from discontinued life businesses	$ (0.4)	$ (0.8)	$ (1.1)	$ (2.0)
Basic:
Loss from discontinued operations	$ (0.01)	$ (0.03)	$ (0.03)	$ (0.05)
Diluted:
Income (Loss) from discontinued operations	$ (0.01)	$ (0.02)	$ (0.03)	$ (0.06)