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	13.3
Other Comprehensive Income	$ 297.7
Net Income	953.2					953.2
Dividends to Stockholders (per common share: $0.420; $0.365; $1.150; $1.025)						(205.8)
Cost of Shares Repurchased	175.4						175.4
Balance at End of Year at Sep. 30, 2023	9,618.1		30.9	2,454.3	(3,150.6)	13,888.7	(3,605.2)
Balance at Beginning of Year at Jun. 30, 2023			30.9	2,444.9	(3,457.6)	13,758.1	(3,530.4)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	9.4
Other Comprehensive Income	307.0				307.0
Net Income	202.0					202.0
Dividends to Stockholders (per common share: $0.420; $0.365; $1.150; $1.025)						(71.4)
Cost of Shares Repurchased	74.8						74.8
Balance at End of Year at Sep. 30, 2023	9,618.1		30.9	2,454.3	(3,150.6)	13,888.7	(3,605.2)
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	15.5
Other Comprehensive Income	578.3				578.3
Net Income	1,430.4					1,430.4
Dividends to Stockholders (per common share: $0.420; $0.365; $1.150; $1.025)						(219.5)
Cost of Shares Repurchased	504.8	[1]					504.8
Balance at End of Year at Sep. 30, 2024	10,951.4		19.5	1,563.3	(2,729.7)	12,642.4	(544.1)
Balance at Beginning of Year at Jun. 30, 2024			19.5	1,558.8	(2,846.2)	12,074.6	(342.1)
Increase (Decrease) in Stockholders' Equity
Common Stock Activity			0.0	4.5
Other Comprehensive Income	116.5				116.5
Net Income	645.7					645.7
Dividends to Stockholders (per common share: $0.420; $0.365; $1.150; $1.025)						(77.9)
Cost of Shares Repurchased	202.0	[1]					202.0
Balance at End of Year at Sep. 30, 2024	$ 10,951.4		$ 19.5	$ 1,563.3	$ (2,729.7)	$ 12,642.4	$ (544.1)

[1] 1Includes a de minimis amount of commissions for the three and nine months ended September 30, 2024 and a de minimis amount and $0.1 million of commissions for the three and nine months ended September 30, 2023, respectively. Also includes $2.0 million and $4.8 million of excise tax for the three and nine months ended September 30, 2024, respectively, and $0.7 million and $1.2 million of excise tax for the three and nine months ended September 30, 2023, respectively.