CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2023	$ 3,855.4	$ 293.7	$ (2,878.2)	$ 454.8	$ 6,012.3	$ (27.2)
Beginning Balance (in shares) at Dec. 31, 2023		293,700,000
Beginning Balance (in shares) at Dec. 31, 2023			(50,600,000)
Net income	227.7	$ 0.0	$ 0.0	0.0	227.7	0.0
Other comprehensive income (loss)	(2.1)	0.0	0.0	0.0	0.0	(2.1)
Cash dividends	(69.0)	0.0	0.0	0.0	(69.0)	0.0
Stock based compensation expense and stock option plan transactions	88.7	$ 0.0	$ 45.4	43.5	(0.2)	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	1,400,000
Ending Balance at Mar. 31, 2024	4,100.7	$ 293.7	$ (2,832.8)	498.3	6,170.8	(29.3)
Ending Balance (in shares) at Mar. 31, 2024		293,700,000
Ending Balance (in shares) at Mar. 31, 2024			(49,200,000)
Beginning Balance at Dec. 31, 2023	3,855.4	$ 293.7	$ (2,878.2)	454.8	6,012.3	(27.2)
Beginning Balance (in shares) at Dec. 31, 2023		293,700,000
Beginning Balance (in shares) at Dec. 31, 2023			(50,600,000)
Net income	471.2
Other comprehensive income (loss)	(1.9)
Ending Balance at Jun. 30, 2024	4,305.5	$ 293.7	$ (2,823.0)	518.7	6,345.2	(29.1)
Ending Balance (in shares) at Jun. 30, 2024		293,700,000
Ending Balance (in shares) at Jun. 30, 2024			(48,900,000)
Beginning Balance at Mar. 31, 2024	4,100.7	$ 293.7	$ (2,832.8)	498.3	6,170.8	(29.3)
Beginning Balance (in shares) at Mar. 31, 2024		293,700,000
Beginning Balance (in shares) at Mar. 31, 2024			(49,200,000)
Net income	243.5	$ 0.0	$ 0.0	0.0	243.5	0.0
Other comprehensive income (loss)	0.2	0.0	0.0	0.0	0.0	0.2
Cash dividends	(69.2)	0.0	0.0	0.0	(69.2)	0.0
Stock based compensation expense and stock option plan transactions	30.3	$ 0.0	$ 9.8	20.4	0.1	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	300,000
Ending Balance at Jun. 30, 2024	4,305.5	$ 293.7	$ (2,823.0)	518.7	6,345.2	(29.1)
Ending Balance (in shares) at Jun. 30, 2024		293,700,000
Ending Balance (in shares) at Jun. 30, 2024			(48,900,000)
Beginning Balance at Dec. 31, 2024	$ 4,360.8	$ 293.7	$ (2,784.8)	563.1	6,319.7	(30.9)
Beginning Balance (in shares) at Dec. 31, 2024		293,700,000
Beginning Balance (in shares) at Dec. 31, 2024	47,830,141		(47,800,000)
Net income	$ 220.1	$ 0.0	$ 0.0	0.0	220.1	0.0
Other comprehensive income (loss)	4.8	0.0	0.0	0.0	0.0	4.8
Cash dividends	(72.4)	0.0	0.0	0.0	(72.4)	0.0
Stock based compensation expense and stock option plan transactions	37.7	$ 0.0	$ 10.7	27.2	(0.2)	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	300,000
Ending Balance at Mar. 31, 2025	4,551.0	$ 293.7	$ (2,774.1)	590.3	6,467.2	(26.1)
Ending Balance (in shares) at Mar. 31, 2025		293,700,000
Ending Balance (in shares) at Mar. 31, 2025			(47,500,000)
Beginning Balance at Dec. 31, 2024	$ 4,360.8	$ 293.7	$ (2,784.8)	563.1	6,319.7	(30.9)
Beginning Balance (in shares) at Dec. 31, 2024		293,700,000
Beginning Balance (in shares) at Dec. 31, 2024	47,830,141		(47,800,000)
Net income	$ 411.1
Other comprehensive income (loss)	12.5
Ending Balance at Jun. 30, 2025	$ 4,393.7	$ 293.7	$ (3,039.5)	572.5	6,585.4	(18.4)
Ending Balance (in shares) at Jun. 30, 2025		293,700,000
Ending Balance (in shares) at Jun. 30, 2025	50,151,459		(50,200,000)
Beginning Balance at Mar. 31, 2025	$ 4,551.0	$ 293.7	$ (2,774.1)	590.3	6,467.2	(26.1)
Beginning Balance (in shares) at Mar. 31, 2025		293,700,000
Beginning Balance (in shares) at Mar. 31, 2025			(47,500,000)
Net income	191.0	$ 0.0	$ 0.0	0.0	191.0	0.0
Other comprehensive income (loss)	7.7	0.0	0.0	0.0	0.0	7.7
Cash dividends	(72.6)	$ 0.0	$ 0.0	0.0	(72.6)	0.0
Stock purchases (in shares)		0	(2,800,000)
Stock purchases	(300.0)	$ 0.0	$ (270.0)	(30.0)	0.0	0.0
Stock based compensation expense and stock option plan transactions	16.6	$ 0.0	$ 4.6	12.2	(0.2)	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	100,000
Ending Balance at Jun. 30, 2025	$ 4,393.7	$ 293.7	$ (3,039.5)	$ 572.5	$ 6,585.4	$ (18.4)
Ending Balance (in shares) at Jun. 30, 2025		293,700,000
Ending Balance (in shares) at Jun. 30, 2025	50,151,459		(50,200,000)