Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues
Premiums	$ 1,095.1	$ 1,042.5
Net investment income	70.2	66.0
Net realized and unrealized investment gains (losses):
Net realized gains (losses) from sales and other	(0.4)	0.6
Net change in fair value of equity securities	48.6	(22.9)
Net other–than–temporary impairment losses on investments recognized in earnings		(0.6)
Total net realized and unrealized investment gains (losses)	48.2	(22.9)
Fees and other income	6.0	5.9
Total revenues	1,219.5	1,091.5
Losses and expenses
Losses and loss adjustment expenses	699.6	670.9
Amortization of deferred acquisition costs	229.5	218.7
Interest expense	9.4	11.3
Other operating expenses	132.4	131.5
Total losses and expenses	1,070.9	1,032.4
Income from continuing operations before income taxes	148.6	59.1
Income tax expense:
Current	12.2	(5.7)
Deferred	13.8	14.3
Total income tax expense	26.0	8.6
Income from continuing operations	122.6	50.5
Discontinued operations:
Net income	$ 122.4	$ 67.7
Basic:
Income from continuing operations	$ 3.02	$ 1.19
Net income per share	$ 3.01	$ 1.59
Weighted average shares outstanding	40.6	42.5
Diluted:
Income from continuing operations	$ 2.98	$ 1.17
Net income per share	$ 2.97	$ 1.57
Weighted average shares outstanding	41.2	43.1
Chaucer [Member]
Revenues
Premiums		$ 221.1
Net investment income		16.4
Net realized and unrealized investment gains (losses):
Total revenues	$ 2.9	239.4
Losses and expenses
Losses and loss adjustment expenses		115.0
Amortization of deferred acquisition costs		69.3
Interest expense		1.1
Other operating expenses		32.2
Total losses and expenses		216.5
Discontinued operations:
Gain from sale of business, net of taxes	0.9
Income (loss) from discontinued operations	$ (0.3)	$ 17.3
Basic:
Gain from sale of business, net of taxes	$ 0.02
Income (loss) from discontinued operations	(0.01)	$ 0.40
Diluted:
Gain from sale of business, net of taxes	0.02
Income (loss) from discontinued operations	$ (0.01)	$ 0.40
Life [Member]
Discontinued operations:
Income (loss) from discontinued operations	$ (0.8)	$ (0.1)
Basic:
Income (loss) from discontinued operations	$ (0.02)
Diluted:
Income (loss) from discontinued operations	$ (0.02)