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	10.6
Other Comprehensive Income (Loss)	$ (152.1)				(152.1)
Net Income	335.9					335.9
Dividends to Stockholders (per common share: $0.300; $0.285; $0.600; $0.570)						(117.9)
Cost of Shares Repurchased	0.0	[1]					0.0
Balance at End of Year at Jun. 30, 2021	10,947.5		30.7	2,386.8	222.1	11,487.6	(3,179.7)
Balance at Beginning of Year at Mar. 31, 2021			30.7	2,380.8	(24.9)	11,363.2	(3,179.7)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	6.0
Other Comprehensive Income (Loss)	247.0				247.0
Net Income	182.9					182.9
Dividends to Stockholders (per common share: $0.300; $0.285; $0.600; $0.570)						(58.5)
Cost of Shares Repurchased	0.0	[1]					0.0
Balance at End of Year at Jun. 30, 2021	10,947.5		30.7	2,386.8	222.1	11,487.6	(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	9.3
Other Comprehensive Income (Loss)	(2,126.3)				(2,126.3)
Net Income	623.9					623.9
Dividends to Stockholders (per common share: $0.300; $0.285; $0.600; $0.570)						(123.4)
Cost of Shares Repurchased	94.9	[1]					94.9
Balance at End of Year at Jun. 30, 2022	9,705.1		30.8	2,417.4	(1,772.2)	12,353.7	(3,324.6)
Balance at Beginning of Year at Mar. 31, 2022			30.8	2,395.8	(580.1)	12,043.8	(3,267.2)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	21.6
Other Comprehensive Income (Loss)	(1,192.1)				(1,192.1)
Net Income	370.4					370.4
Dividends to Stockholders (per common share: $0.300; $0.285; $0.600; $0.570)						(60.5)
Cost of Shares Repurchased	57.4	[1]					57.4
Balance at End of Year at Jun. 30, 2022	$ 9,705.1		$ 30.8	$ 2,417.4	$ (1,772.2)	$ 12,353.7	$ (3,324.6)

[1] Includes commissions of $0.1 million for the three and six months ended June 30, 2022.