CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total		Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock, Common
Balance at Beginning of Year at Dec. 31, 2022			$ 30.8	$ 2,441.0	$ (3,448.3)	$ 13,141.3	$ (3,429.8)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.1	3.9
Other Comprehensive Income (Loss)	$ (9.3)
Net Income	751.2					751.2
Dividends to Stockholders (per common share: $0.365; $0.330; $0.730; $0.660)						(134.4)
Cost of Shares Repurchased	100.6						100.6
Balance at End of Year at Jun. 30, 2023	9,245.9		30.9	2,444.9	(3,457.6)	13,758.1	(3,530.4)
Balance at Beginning of Year at Mar. 31, 2023			30.9	2,431.8	(3,162.3)	13,430.4	(3,483.4)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	13.1
Other Comprehensive Income (Loss)	(295.3)				(295.3)
Net Income	392.9					392.9
Dividends to Stockholders (per common share: $0.365; $0.330; $0.730; $0.660)						(65.2)
Cost of Shares Repurchased	47.0						47.0
Balance at End of Year at Jun. 30, 2023	9,245.9		30.9	2,444.9	(3,457.6)	13,758.1	(3,530.4)
Balance at Beginning of Year at Dec. 31, 2023	9,651.4		19.4	1,547.8	(3,308.0)	11,431.5	(39.3)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.1	11.0
Other Comprehensive Income (Loss)	461.8				461.8
Net Income	784.7					784.7
Dividends to Stockholders (per common share: $0.365; $0.330; $0.730; $0.660)						(141.6)
Cost of Shares Repurchased	302.8	[1]					302.8
Balance at End of Year at Jun. 30, 2024	10,464.6		19.5	1,558.8	(2,846.2)	12,074.6	(342.1)
Balance at Beginning of Year at Mar. 31, 2024			19.5	1,548.2	(2,940.0)	11,754.1	(162.3)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	10.6
Other Comprehensive Income (Loss)	93.8				93.8
Net Income	389.5					389.5
Dividends to Stockholders (per common share: $0.365; $0.330; $0.730; $0.660)						(69.0)
Cost of Shares Repurchased	179.8	[1]					179.8
Balance at End of Year at Jun. 30, 2024	$ 10,464.6		$ 19.5	$ 1,558.8	$ (2,846.2)	$ 12,074.6	$ (342.1)

[1] 1Includes a de minimis amount of commissions for the three and six months ended June 30, 2024 and $0.1 million of commissions for the three and six months ended June 30, 2023. Also includes $1.7 million and $2.8 million of excise tax for the three and six months ended June 30, 2024, respectively, and $0.4 million and $0.5 million of excise tax for the three and six months ended June 30, 2023, respectively.