Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Par	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2018	$ 1,322.0	$ 1.1	$ 798.3	$ 1,726.5	$ (108.0)	$ (1,095.9)
Increase (Decrease) in Stockholders' Equity
Net income	306.6			306.6
Dividends paid on common stock	(54.2)			(54.2)
Change in other comprehensive income (loss) - net of tax	(10.7)				(10.7)
Stock-based activity	31.6		31.6
Acquisition of treasury stock	(149.2)					(149.2)
Ending Balance at Dec. 31, 2019	1,446.1	1.1	829.9	1,978.9	(118.7)	(1,245.1)
Increase (Decrease) in Stockholders' Equity
Net income	31.7			31.7
Dividends paid on common stock	(14.2)			(14.2)
Change in other comprehensive income (loss) - net of tax	59.1				59.1
Stock-based activity	19.8		19.8
Acquisition of treasury stock	(32.3)					(32.3)
Ending Balance at Dec. 31, 2020	1,510.2	1.1	849.7	1,996.4	(59.6)	(1,277.4)
Increase (Decrease) in Stockholders' Equity
Net income	16.1			16.1
Change in other comprehensive income (loss) - net of tax	(66.9)				(66.9)
Stock-based activity	26.1		28.9			(2.8)
Ending Balance at Dec. 31, 2021	$ 1,485.5	$ 1.1	$ 878.6	$ 2,012.5	$ (126.5)	$ (1,280.2)