Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Shares outstanding, beginning (in shares) at Dec. 31, 2021		76.2
Shareholders' equity, beginning at Dec. 31, 2021	$ 306.8	$ 0.0	$ 307.7	$ (0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	42.1		42.1
Issuance of common stock (in shares)		0.2
Repurchase of common stock (in shares)		(0.2)
Repurchase of common stock	(25.0)	$ (7.0)	(18.0)
Taxes paid related to net share settlement of stock awards (in shares)		(0.2)
Taxes paid related to net share settlement of stock awards	(13.1)		(13.1)
Stock-based compensation	7.0	$ 7.0
Shares outstanding, ending (in shares) at Mar. 31, 2022		76.0
Shareholders' equity, ending at Mar. 31, 2022	317.8	$ 0.0	318.7	(0.9)
Shares outstanding, beginning (in shares) at Dec. 31, 2021		76.2
Shareholders' equity, beginning at Dec. 31, 2021	306.8	$ 0.0	307.7	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	438.4
Shares outstanding, ending (in shares) at Sep. 30, 2022		74.8
Shareholders' equity, ending at Sep. 30, 2022	612.7	$ 0.0	613.6	(0.9)
Shares outstanding, beginning (in shares) at Mar. 31, 2022		76.0
Shareholders' equity, beginning at Mar. 31, 2022	317.8	$ 0.0	318.7	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	339.3		339.3
Repurchase of common stock (in shares)		(0.6)
Repurchase of common stock	(61.5)	$ (7.4)	(54.1)
Taxes paid related to net share settlement of stock awards	(0.1)		(0.1)
Stock-based compensation	7.4	$ 7.4
Shares outstanding, ending (in shares) at Jun. 30, 2022		75.4
Shareholders' equity, ending at Jun. 30, 2022	602.9	$ 0.0	603.8	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	57.0		57.0
Issuance of common stock	2.7	$ 2.7
Repurchase of common stock (in shares)		(0.6)
Repurchase of common stock	(59.0)	$ (11.8)	(47.2)
Stock-based compensation	9.1	$ 9.1
Shares outstanding, ending (in shares) at Sep. 30, 2022		74.8
Shareholders' equity, ending at Sep. 30, 2022	612.7	$ 0.0	613.6	(0.9)
Shares outstanding, beginning (in shares) at Dec. 31, 2022		74.8
Shareholders' equity, beginning at Dec. 31, 2022	551.5	$ 0.0	552.4	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	155.7		155.7
Issuance of common stock (in shares)		0.2
Taxes paid related to net share settlement of stock awards (in shares)		(0.1)
Taxes paid related to net share settlement of stock awards	(11.3)	$ (8.6)	(2.7)
Stock-based compensation	8.6	$ 8.6
Other	(0.3)		(0.3)
Shares outstanding, ending (in shares) at Mar. 31, 2023		74.9
Shareholders' equity, ending at Mar. 31, 2023	704.2	$ 0.0	705.1	(0.9)
Shares outstanding, beginning (in shares) at Dec. 31, 2022		74.8
Shareholders' equity, beginning at Dec. 31, 2022	551.5	$ 0.0	552.4	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	359.7
Shares outstanding, ending (in shares) at Sep. 30, 2023		74.6
Shareholders' equity, ending at Sep. 30, 2023	888.7	$ 0.0	889.6	(0.9)
Shares outstanding, beginning (in shares) at Mar. 31, 2023		74.9
Shareholders' equity, beginning at Mar. 31, 2023	704.2	$ 0.0	705.1	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	143.0		143.0
Taxes paid related to net share settlement of stock awards	(0.1)
Stock-based compensation	8.1	$ 8.1
Other	(1.4)		(1.4)
Shares outstanding, ending (in shares) at Jun. 30, 2023		74.9
Shareholders' equity, ending at Jun. 30, 2023	853.8	$ 8.0	846.7	(0.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	61.0		61.0
Issuance of common stock	3.1	$ 3.1
Repurchase of common stock (in shares)		(0.3)
Repurchase of common stock	(37.3)	$ (19.2)	(18.1)
Stock-based compensation	8.1	$ 8.1
Shares outstanding, ending (in shares) at Sep. 30, 2023		74.6
Shareholders' equity, ending at Sep. 30, 2023	$ 888.7	$ 0.0	$ 889.6	$ (0.9)