Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities:
Net Income	$ 190.1	$ 120.9	$ 16.8
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Increase in Deferred Policy Acquisition Costs	(104.6)	(33.3)	(15.6)
Amortization of Intangible Assets Acquired	156.3	5.1	5.9
Equity in Earnings of Equity Method Limited Liability Investments	(11.0)	(24.8)	(7.5)
Distribution of Accumulated Earnings of Equity Method Limited Liability Investments	13.9	19.6	15.7
Decrease (Increase) in Value of Fair Value Option Investments reported in Investment Income	0.0	(1.3)	1.9
Equity Securities, FV-NI, Gain (Loss)	64.3	0.0	0.0
Amortization of Investment Securities and Depreciation of Investment Real Estate	7.7	16.7	16.2
Debt and Equity Securities, Realized Gain (Loss)	26.4	56.5	33.1
Net Impairment Losses Recognized in Earnings	4.5	14.3	32.7
Depreciation of Property and Equipment	15.6	13.1	13.6
Increase in Other Receivables	(80.7)	(29.2)	(11.0)
Increase in Insurance Reserves	183.2	131.1	201.8
Increase in Unearned Premiums	54.7	35.2	5.6
Change in Income Taxes	13.1	28.9	(6.5)
Increase in Accrued Expenses and Other Liabilities	49.9	2.9	3.3
Other, Net	8.6	(2.1)	0.7
Net Cash Provided by Operating Activities	539.2	240.6	240.5
Investing Activities:
Sales, Paydowns and Maturities of Fixed Maturities	2,643.3	528.2	532.3
Purchases of Fixed Maturities	(2,413.2)	(710.1)	(850.3)
Sales of Equity Securities	351.9	342.0	158.9
Purchases of Equity Securities	(478.5)	(342.7)	(90.1)
Acquisition and Improvements of Investment Real Estate	(1.5)	(1.5)	(2.2)
Sales of Investment Real Estate	0.0	26.7	7.5
Sales of and Return of Investment of Equity Method Limited Liability Investments	14.1	48.1	41.0
Acquisitions of Equity Method Limited Liability Investments	(43.1)	(27.9)	(34.6)
Sales of Fair Value Option Investments	0.0	42.2	72.2
Purchases of Fair Value Option Investments	0.0	(7.0)	(21.0)
Decrease (Increase) in Short-term Investments	52.7	39.4	(18.0)
Acquisition of Businesses, Net of Cash Acquired	(560.6)	0.0	0.0
Increase in Other Investments	(2.0)	(4.5)	(5.7)
Purchase of Corporate-owned Life Insurance	0.0	0.0	(7.5)
Acquisition of Software and Long-lived Assets	(65.3)	(35.5)	(17.6)
Other, Net	4.6	(2.8)	(3.0)
Net Cash Used by Investing Activities	(497.6)	(105.4)	(238.1)
Financing Activities:
Net Proceeds from Issuances of Debt	249.4	200.2	0.0
Repayments of Debt	(215.0)	(360.0)	0.0
Proceeds from Short-term Debt, Maturing in More than Three Months	10.0	0.0	0.0
Common Stock Repurchases	0.0	0.0	(3.8)
Dividends and Dividend Equivalents Paid	(56.4)	(49.5)	(49.2)
Cash Exercise of Stock Options	0.9	4.0	3.5
Other, Net	(1.1)	0.1	1.1
Net Cash Used by Financing Activities	(12.2)	(205.2)	(48.4)
Increase (Decrease) in Cash	29.4	(70.0)	(46.0)
Cash, Beginning of Year	45.7	115.7	161.7
Cash, End of Year	$ 75.1	$ 45.7	$ 115.7