CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDER'S EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-in Capital	Retained Earnings	Other
Common Stock, Shares		51.8
Total stockholders’ equity at Dec. 31, 2021	$ 1,865.4	$ 0.5	$ 690.8	$ 1,174.4	$ (0.3)
Stock-based compensation expense	35.9		35.9
Employee stock purchase plan, shares		0.4
Employee stock purchase plan, value	18.9		18.9
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(12.9)		(12.9)
Vesting of restricted stock units, shares		0.0
Stock Repurchased and Retired During Period, Shares		(2.2)
Stock Repurchased and Retired During Period, Value	(226.8)		(30.0)	(196.8)
Foreign currency translation adjustments	(3.9)				(3.9)
Net income	212.5			212.5
Shares Outstanding at Sep. 30, 2022		50.0
Total stockholders’ equity at Sep. 30, 2022	1,889.1	$ 0.5	702.7	1,190.1	(4.2)
Common Stock, Shares		50.4
Total stockholders’ equity at Jun. 30, 2022	1,856.1	$ 0.5	692.1	1,165.5	(2.0)
Stock-based compensation expense	11.9		11.9
Employee stock purchase plan, shares		0.2
Employee stock purchase plan, value	8.5		8.5
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(1.6)		(1.6)
Vesting of restricted stock units, shares		0.0
Stock Repurchased and Retired During Period, Shares		(0.6)
Stock Repurchased and Retired During Period, Value	(56.8)		(8.2)	(48.6)
Foreign currency translation adjustments	(2.2)				(2.2)
Net income	73.2			73.2
Shares Outstanding at Sep. 30, 2022		50.0
Total stockholders’ equity at Sep. 30, 2022	1,889.1	$ 0.5	702.7	1,190.1	(4.2)
Total stockholders’ equity at Dec. 31, 2022	1,901.3	$ 0.5	703.5	1,200.0	(2.7)
Stock-based compensation expense	33.7		33.7
Employee stock purchase plan, shares		0.6
Employee stock purchase plan, value	18.9		18.9
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(15.7)		(15.7)
Vesting of restricted stock units, shares		0.0
Stock Repurchased and Retired During Period, Shares		(2.6)
Stock Repurchased and Retired During Period, Value	(199.6)		(38.5)	(161.1)
Foreign currency translation adjustments	1.1				1.1
Net income	169.0			169.0
Shares Outstanding at Sep. 30, 2023		47.5
Total stockholders’ equity at Sep. 30, 2023	1,908.7	$ 0.5	701.9	1,207.9	(1.6)
Common Stock, Shares		48.5
Total stockholders’ equity at Jun. 30, 2023	1,926.6	$ 0.5	702.8	1,223.6	(0.3)
Stock-based compensation expense	10.3		10.3
Employee stock purchase plan, shares		0.2
Employee stock purchase plan, value	7.8		7.8
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(1.5)		(1.5)
Vesting of restricted stock units, shares		0.0
Stock Repurchased and Retired During Period, Shares		(1.2)
Stock Repurchased and Retired During Period, Value	(92.6)		(17.5)	(75.1)
Foreign currency translation adjustments	(1.3)				(1.3)
Net income	59.4			59.4
Shares Outstanding at Sep. 30, 2023		47.5
Total stockholders’ equity at Sep. 30, 2023	$ 1,908.7	$ 0.5	$ 701.9	$ 1,207.9	$ (1.6)