CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Capital Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance, beginning of period at Dec. 31, 2020		$ 18.7	$ 148.0	$ 873.7	$ (19.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for vested restricted stock units, net of shares withheld for taxes		0.0	(2.9)
Shares repurchased		0.0	0.0
Other capital stock activity		0.0
Other additional paid-in capital activity			1.5
Equity compensation expense			17.0
Net income	$ 108.1			108.1
Other comprehensive income (loss)	(25.6)				(25.6)
Balance, end of period at Dec. 31, 2021	1,118.9	18.7	163.6	981.8	(45.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for vested restricted stock units, net of shares withheld for taxes		0.1	(10.9)
Shares repurchased	(25.0)	(0.2)	(24.8)
Other capital stock activity		0.0
Other additional paid-in capital activity			1.0
Equity compensation expense			11.8
Net income	116.6			116.6
Other comprehensive income (loss)	(40.0)				(40.0)
Balance, end of period at Dec. 31, 2022	1,172.5	18.6	140.7	1,098.4	(85.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for vested restricted stock units, net of shares withheld for taxes		0.0	(3.2)
Shares repurchased		0.0	0.0
Other capital stock activity		0.0
Other additional paid-in capital activity			0.0
Equity compensation expense			14.3
Net income	56.6			56.6
Other comprehensive income (loss)	18.8				18.8
Balance, end of period at Dec. 31, 2023	$ 1,259.0	$ 18.6	$ 151.8	$ 1,155.0	$ (66.4)