CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Treasury Stock, Common [Member]	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2021	$ 3,233.2	$ 292.8	$ (2,667.7)	$ 310.3	$ 5,366.0	$ (68.2)
Beginning Balance (in shares) at Dec. 31, 2021		292.8	(50.3)
Net income	204.4	$ 0.0	$ 0.0	0.0	204.4	0.0
Other comprehensive income (loss)	15.0	0.0	0.0	0.0	0.0	15.0
Cash dividends	(63.7)	0.0	0.0	0.0	(63.7)	0.0
Stock purchases			$ 20.0	(20.0)
Stock purchases (in shares)			0.2
Stock based compensation expense and stock option plan transactions	14.0	$ 0.0	$ 10.1	3.9	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	0.3
Ending Balance at Mar. 31, 2022	3,402.9	$ 292.8	$ (2,677.6)	334.2	5,506.7	(53.2)
Ending Balance (in shares) at Mar. 31, 2022		292.8	(50.2)
Beginning Balance at Dec. 31, 2021	3,233.2	$ 292.8	$ (2,667.7)	310.3	5,366.0	(68.2)
Beginning Balance (in shares) at Dec. 31, 2021		292.8	(50.3)
Net income	391.5
Other comprehensive income (loss)	21.1
Ending Balance at Jun. 30, 2022	3,554.4	$ 292.8	$ (2,671.5)	350.1	5,630.1	(47.1)
Ending Balance (in shares) at Jun. 30, 2022		292.8	(50)
Beginning Balance at Mar. 31, 2022	3,402.9	$ 292.8	$ (2,677.6)	334.2	5,506.7	(53.2)
Beginning Balance (in shares) at Mar. 31, 2022		292.8	(50.2)
Net income	187.1	$ 0.0	$ 0.0	0.0	187.1	0.0
Other comprehensive income (loss)	6.1	0.0	0.0	0.0	0.0	6.1
Cash dividends	(63.7)	0.0	0.0	0.0	(63.7)	0.0
Stock based compensation expense and stock option plan transactions	22.0	$ 0.0	$ 6.1	15.9	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	0.2
Ending Balance at Jun. 30, 2022	3,554.4	$ 292.8	$ (2,671.5)	350.1	5,630.1	(47.1)
Ending Balance (in shares) at Jun. 30, 2022		292.8	(50)
Beginning Balance at Dec. 31, 2022	3,489.9	$ 293.7	$ (2,665.3)	366.2	5,524.6	(29.3)
Beginning Balance (in shares) at Dec. 31, 2022		293.7	(49.8)
Net income	203.2	$ 0.0	$ 0.0	0.0	203.2	0.0
Other comprehensive income (loss)	3.1	0.0	0.0	0.0	0.0	3.1
Cash dividends	(66.3)				(66.3)
Stock based compensation expense and stock option plan transactions	37.8	$ 0.0	$ 10.3	27.8	(0.3)	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	0.3
Ending Balance at Mar. 31, 2023	3,667.7	$ 293.7	$ (2,655.0)	394.0	5,661.2	(26.2)
Ending Balance (in shares) at Mar. 31, 2023		293.7	(49.5)
Beginning Balance at Dec. 31, 2022	3,489.9	$ 293.7	$ (2,665.3)	366.2	5,524.6	(29.3)
Beginning Balance (in shares) at Dec. 31, 2022		293.7	(49.8)
Net income	424.4
Other comprehensive income (loss)	1.5
Ending Balance at Jun. 30, 2023	3,911.0	$ 293.7	$ (2,592.8)	422.6	5,815.3	(27.8)
Ending Balance (in shares) at Jun. 30, 2023		293.7	(47.7)
Beginning Balance at Mar. 31, 2023	3,667.7	$ 293.7	$ (2,655.0)	394.0	5,661.2	(26.2)
Beginning Balance (in shares) at Mar. 31, 2023		293.7	(49.5)
Net income	221.2	$ 0.0	$ 0.0	0.0	221.2	0.0
Other comprehensive income (loss)	(1.6)	0.0	0.0	0.0	0.0	(1.6)
Cash dividends	(66.7)	0.0	0.0	0.0	(66.7)	0.0
Stock based compensation expense and stock option plan transactions	90.4	$ 0.0	$ 62.2	28.6	(0.4)	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0	1.8
Ending Balance at Jun. 30, 2023	$ 3,911.0	$ 293.7	$ (2,592.8)	$ 422.6	$ 5,815.3	$ (27.8)
Ending Balance (in shares) at Jun. 30, 2023		293.7	(47.7)