CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net Income	$ 1,100.3	$ 523.4	$ 994.2
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Change in Receivables	37.5	(4.7)	(101.8)
Change in Deferred Acquisition Costs	(48.7)	(102.5)	(100.9)
Change in Insurance Reserves and Liabilities	376.1	1,193.1	441.9
Change in Income Taxes	248.2	(39.1)	25.6
Change in Other Accrued Liabilities	51.3	(10.1)	14.6
Non-cash Components of Net Investment Income	(237.9)	(211.1)	(200.1)
Net Realized Investment (Gain) Loss	23.2	39.5	(40.3)
Depreciation	110.1	101.4	103.4
Other, Net	81.5	46.6	27.5
Net Cash Provided by Operating Activities	1,741.6	1,536.5	1,164.1
Cash Flows from Investing Activities
Proceeds from Sales of Fixed Maturity Securities	955.2	642.5	436.3
Proceeds from Maturities of Fixed Maturity Securities	2,401.0	2,815.4	2,560.8
Proceeds from Sales and Maturities of Other Investments	363.5	454.0	257.9
Purchase of Fixed Maturity Securities	(4,022.4)	(3,861.7)	(2,808.5)
Purchase of Other Investments	(568.5)	(623.2)	(474.3)
Net Sales (Purchases) of Short-term Investments	(267.6)	200.5	(356.4)
Net Decrease in Payables for Collateral on Investments	(104.1)	(268.1)	(9.8)
Acquisition of Business (Net of Cash Acquired)	0.0	(145.4)	0.0
Net Purchases of Property and Equipment	(150.9)	(144.1)	(105.3)
Other, Net	(0.3)	0.0	0.0
Net Cash Used by Investing Activities	(1,393.5)	(930.1)	(499.3)
Cash Flows from Financing Activities
Short-term Debt Repayment	0.0	(200.0)	0.0
Issuance of Long-term Debt	841.9	290.7	0.0
Long-term Debt Repayment	(493.1)	(60.0)	(63.5)
Cost Related to Early Retirement of Debt	25.9	0.0	0.0
Issuance of Common Stock	6.1	4.6	10.8
Repurchase of Common Stock	(400.3)	(356.2)	(401.8)
Dividends Paid to Stockholders	(229.2)	(215.6)	(196.0)
Other, Net	(57.5)	(53.3)	(37.3)
Net Cash Used by Financing Activities	(358.0)	(589.8)	(687.8)
Net Increase (Decrease) in Cash and Bank Deposits	(9.9)	16.6	(23.0)
Cash and Bank Deposits at Beginning of Year	94.0	77.4	100.4
Cash and Bank Deposits at End of Year	$ 84.1	$ 94.0	$ 77.4