CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2018	$ 2,453.8	$ 292.8	$ (1,898.8)	$ 280.8	$ 3,832.6	$ (53.6)
Beginning Balance (in shares) at Dec. 31, 2018		292.8	(46.0)
Adoption of new accounting pronouncements	13.0	$ 0.0	$ 0.0	0.0	13.0	0.0
Net Income	615.9	0.0	0.0	0.0	615.9	0.0
Other comprehensive (loss) income	(13.1)	0.0	0.0	0.0	0.0	(13.1)
Cash dividends	(224.1)	(0.0)	(0.0)	(0.0)	(224.1)	(0.0)
Stock purchases	(250.0)	$ (0.0)	$ (250.0)	(0.0)	(0.0)	(0.0)
Stock purchases (in shares)		(0.0)	(3.6)
Stock based compensation expense and stock option plan transactions	72.3	$ 0.0	$ 57.6	14.7	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	2.2
Ending Balance at Dec. 31, 2019	2,667.8	$ 292.8	$ (2,091.2)	295.5	4,237.4	(66.7)
Ending Balance (in shares) at Dec. 31, 2019		292.8	(47.4)
Net Income	785.9	$ 0.0	$ 0.0	0.0	785.9	0.0
Other comprehensive (loss) income	(10.9)	0.0	0.0	0.0	0.0	(10.9)
Cash dividends	(237.3)	(0.0)	(0.0)	(0.0)	(237.3)	(0.0)
Stock purchases	(300.0)	$ (0.0)	$ (270.0)	(30.0)	(0.0)	(0.0)
Stock purchases (in shares)		(0.0)	(3.1)
Stock based compensation expense and stock option plan transactions	114.9	$ 0.0	$ 106.0	8.9	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	3.1
Ending Balance at Dec. 31, 2020	3,020.4	$ 292.8	$ (2,255.2)	274.4	4,786.0	(77.6)
Ending Balance (in shares) at Dec. 31, 2020		292.8	(47.4)
Net Income	827.5	$ 0.0	$ 0.0	0.0	827.5	0.0
Other comprehensive (loss) income	9.4	0.0	0.0	0.0	0.0	9.4
Cash dividends	(247.5)	(0.0)	(0.0)	(0.0)	(247.5)	(0.0)
Stock purchases	(500.0)	$ (0.0)	$ (510.0)	10.0	(0.0)	(0.0)
Stock purchases (in shares)		(0.0)	(5.7)
Stock based compensation expense and stock option plan transactions	123.4	$ 0.0	$ 97.5	25.9	0.0	0.0
Stock based compensation expense and stock option plan transactions (in shares)		0.0	2.8
Ending Balance at Dec. 31, 2021	$ 3,233.2	$ 292.8	$ (2,667.7)	$ 310.3	$ 5,366.0	$ (68.2)
Ending Balance (in shares) at Dec. 31, 2021		292.8	(50.3)