CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Balance at Beginning of Year at Dec. 31, 2020		$ 30.7	$ 2,376.2	$ 374.2	$ 11,269.6	$ (3,179.7)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity		0.0	4.6
Other Comprehensive Loss	$ (399.1)			(399.1)
Net Income	153.0				153.0
Dividends to Stockholders (per common share: $0.300; $0.285)					(59.4)
Balance at End of Year at Mar. 31, 2021	10,570.1	30.7	2,380.8	(24.9)	11,363.2	(3,179.7)
Increase (Decrease) in Stockholders' Equity
Cost of Shares Repurchased	0.0		0.0			0.0
Balance at Beginning of Year at Dec. 31, 2021	11,416.4	30.7	2,408.1	354.1	11,853.2	(3,229.7)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity		0.1	0.2
Other Comprehensive Loss	(934.2)			(934.2)
Net Income	253.5				253.5
Dividends to Stockholders (per common share: $0.300; $0.285)					(62.9)
Balance at End of Year at Mar. 31, 2022	10,623.1	$ 30.8	2,395.8	$ (580.1)	$ 12,043.8	(3,267.2)
Increase (Decrease) in Stockholders' Equity
Cost of Shares Repurchased	$ (37.5)		$ (12.5)			$ (37.5)