CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net Income	$ 523.4	$ 994.2	$ 931.4
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Change in Receivables	(4.7)	(101.8)	(167.3)
Change in Deferred Acquisition Costs	(102.5)	(100.9)	(99.4)
Change in Insurance Reserves and Liabilities	1,193.1	441.9	368.2
Change in Income Taxes	(39.1)	25.6	34.7
Change in Other Accrued Liabilities	(10.1)	14.6	125.8
Non-cash Components of Net Investment Income	(211.1)	(200.1)	(187.7)
Net Realized Investment (Gain) Loss	39.5	(40.3)	(24.2)
Depreciation	101.4	103.4	101.7
Other, Net	46.6	27.5	38.4
Net Cash Provided by Operating Activities	1,536.5	1,164.1	1,121.6
Cash Flows from Investing Activities
Proceeds from Sales of Fixed Maturity Securities	642.5	436.3	911.5
Proceeds from Maturities of Fixed Maturity Securities	2,815.4	2,560.8	2,197.8
Proceeds from Sales and Maturities of Other Investments	454.0	257.9	331.3
Purchase of Fixed Maturity Securities	(3,861.7)	(2,808.5)	(3,362.8)
Purchase of Other Investments	(623.2)	(474.3)	(576.0)
Net Sales (Purchases) of Short-term Investments	200.5	(356.4)	6.3
Net Increase (Decrease) in Payables for Collateral on Investments	(268.1)	(9.8)	(9.4)
Acquisition of Business (Net of Cash Acquired)	(145.4)	0.0	(129.2)
Net Purchases of Property and Equipment	(144.1)	(105.3)	(85.0)
Net Cash Used by Investing Activities	(930.1)	(499.3)	(715.5)
Cash Flows from Financing Activities
Short-term Debt Repayment	(200.0)	0.0	0.0
Issuance of Long-term Debt	290.7	0.0	609.1
Long-term Debt Repayment	(60.0)	(63.5)	(414.0)
Issuance of Common Stock	4.6	10.8	8.5
Repurchase of Common Stock	(356.2)	(401.8)	(405.2)
Dividends Paid to Stockholders	(215.6)	(196.0)	(182.6)
Other, Net	(53.3)	(37.3)	(34.4)
Net Cash Used by Financing Activities	(589.8)	(687.8)	(418.6)
Net Increase (Decrease) in Cash and Bank Deposits	16.6	(23.0)	(12.5)
Cash and Bank Deposits at Beginning of Year	77.4	100.4	112.9
Cash and Bank Deposits at End of Year	$ 94.0	$ 77.4	$ 100.4