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	22.3
Other Comprehensive Loss	$ (260.3)				(260.3)
Net Income	664.5					664.5
Dividends to Stockholders (per common share: $0.330; $0.300; $0.930; $0.870)						(179.3)
Cost of Shares Repurchased	0.0	[1]					0.0
Balance at End of Year at Sep. 30, 2021	11,118.2		30.7	2,398.5	113.9	11,754.8	(3,179.7)
Balance at Beginning of Year at Jun. 30, 2021			30.7	2,386.8	222.1	11,487.6	(3,179.7)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	11.7
Other Comprehensive Loss	(108.2)				(108.2)
Net Income	328.6					328.6
Dividends to Stockholders (per common share: $0.330; $0.300; $0.930; $0.870)						(61.4)
Cost of Shares Repurchased	0.0	[1]					0.0
Balance at End of Year at Sep. 30, 2021	11,118.2		30.7	2,398.5	113.9	11,754.8	(3,179.7)
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	24.2
Other Comprehensive Loss	(3,488.8)				(3,488.8)
Net Income	1,034.6					1,034.6
Dividends to Stockholders (per common share: $0.330; $0.300; $0.930; $0.870)						(189.5)
Cost of Shares Repurchased	137.5	[1]					137.5
Balance at End of Year at Sep. 30, 2022	8,659.5		30.8	2,432.3	(3,134.7)	12,698.3	(3,367.2)
Balance at Beginning of Year at Jun. 30, 2022			30.8	2,417.4	(1,772.2)	12,353.7	(3,324.6)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	14.9
Other Comprehensive Loss	(1,362.5)				(1,362.5)
Net Income	410.7					410.7
Dividends to Stockholders (per common share: $0.330; $0.300; $0.930; $0.870)						(66.1)
Cost of Shares Repurchased	42.6	[1]					42.6
Balance at End of Year at Sep. 30, 2022	$ 8,659.5		$ 30.8	$ 2,432.3	$ (3,134.7)	$ 12,698.3	$ (3,367.2)

[1] Includes a de minimis amount and $0.1 million of commissions for the three and nine months ended September 30, 2022.