Consolidated Statements of Income - USD ($) shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Premiums	$ 1,161,800,000	$ 1,141,400,000
Net investment income	76,800,000	69,600,000
Net realized and unrealized investment gains (losses):
Net realized gains (losses) from sales and other	(1,600,000)	3,100,000
Net change in fair value of equity securities	39,100,000	(136,200,000)
Impairment losses on investments	0	(28,500,000)
Total net realized and unrealized investment gains (losses)	37,500,000	(161,600,000)
Fees and other income	7,200,000	6,800,000
Total revenues	1,283,300,000	1,056,200,000
Losses and expenses
Losses and loss adjustment expenses	781,300,000	728,200,000
Amortization of deferred acquisition costs	240,300,000	236,900,000
Interest expense	8,500,000	9,400,000
Other operating expenses	139,100,000	135,600,000
Total losses and expenses	1,169,200,000	1,110,100,000
Income (loss) from continuing operations before income taxes	114,100,000	(53,900,000)
Income tax expense (benefit):
Current	8,900,000	21,300,000
Deferred	12,400,000	(36,500,000)
Total income tax expense (benefit)	21,300,000	(15,200,000)
Income (loss) from continuing operations	92,800,000	(38,700,000)
Discontinued operations (net of taxes):
Net income (loss)	$ 92,700,000	$ (40,000,000.0)
Basic:
Income (loss) from continuing operations	$ 2.55	$ (1.01)
Net income (loss) per share	$ 2.55	$ (1.04)
Weighted average shares outstanding	36.4	38.3
Diluted:
Income (loss) from continuing operations	$ 2.52	$ (1.01)
Net income (loss) per share	$ 2.51	$ (1.04)
Weighted average shares outstanding	36.9	38.3
Life [Member]
Discontinued operations (net of taxes):
Income (Loss) from discontinued operations	$ (100,000)	$ (1,300,000)
Basic:
Loss from discontinued operations		$ (0.03)
Diluted:
Income (Loss) from discontinued operations	$ (0.01)	$ (0.03)