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, 2020	$ 3,020.4	$ 292.8	$ (2,255.2)	$ 274.4	$ 4,786.0	$ (77.6)
Beginning Balance (in shares) at Dec. 31, 2020		292.8	(47.4)
Net income	220.7	$ 0.0	$ 0.0	0.0	220.7	0.0
Other comprehensive income (loss)	23.0	0.0	0.0	0.0	0.0	23.0
Stock based compensation expense and stock option plan transactions	9.0	$ 0.0	$ 7.2	1.8	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	0.1
Ending Balance at Mar. 31, 2021	3,211.2	$ 292.8	$ (2,278.0)	306.2	4,944.8	(54.6)
Ending Balance (in shares) at Mar. 31, 2021		292.8	(47.7)
Beginning Balance at Dec. 31, 2020	3,020.4	$ 292.8	$ (2,255.2)	274.4	4,786.0	(77.6)
Beginning Balance (in shares) at Dec. 31, 2020		292.8	(47.4)
Net income	439.0
Other comprehensive income (loss)	11.8
Ending Balance at Jun. 30, 2021	3,377.2	$ 292.8	$ (2,271.5)	320.5	5,101.2	(65.8)
Ending Balance (in shares) at Jun. 30, 2021		292.8	(47.5)
Beginning Balance at Mar. 31, 2021	3,211.2	$ 292.8	$ (2,278.0)	306.2	4,944.8	(54.6)
Beginning Balance (in shares) at Mar. 31, 2021		292.8	(47.7)
Net income	218.3	$ 0.0	$ 0.0	0.0	218.3	0.0
Other comprehensive income (loss)	(11.2)	0.0	0.0	0.0	0.0	(11.2)
Stock based compensation expense and stock option plan transactions	20.8	$ 0.0	$ 6.5	14.3	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	0.2
Ending Balance at Jun. 30, 2021	3,377.2	$ 292.8	$ (2,271.5)	320.5	5,101.2	(65.8)
Ending Balance (in shares) at Jun. 30, 2021		292.8	(47.5)
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
Stock purchases	(0.0)	$ (0.0)	$ 20.0	(20.0)	(0.0)	(0.0)
Stock purchases (in shares)		(0.0)	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	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	(50.0)
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
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	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	(50.0)