Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Comprehensive Loss [Member]
Balance, Beginning at Dec. 31, 2015	$ 1,017.0	$ 153.0	$ (210.6)	$ 496.5	$ 724.2	$ (146.1)
Balance, Beginning, Shares at Dec. 31, 2015		153,000,000	10,000,000
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	15.9			(0.4)	16.3
Net income	149.8				149.8
Payment of cash dividends	0.0
Issuance of shares for employee stock plans and stock-based compensation			(1,500,000)
Issuance of shares for employee stock plans and stock-based compensation, amount	(0.4)		$ (30.8)	(30.4)
Exercise of stock warrants, shares		400,000
Exercise of stock warrants, amount	0.0	$ 0.4		(0.4)
Compensation expense associated with stock awards	12.9			12.9
Taxes paid related to net settlement of equity awards, shares			500,000
Taxes paid related to net share settlement of equity awards	(9.2)		$ (9.2)
Other comprehensive loss	8.9					8.9
Balance, Ending, Shares at Dec. 31, 2016		153,400,000	9,000,000
Balance, Ending at Dec. 31, 2016	1,195.7	$ 153.4	$ (189.0)	478.2	890.3	(137.2)
Net income	389.8				389.8
Payment of cash dividends	0.0
Issuance of shares for employee stock plans and stock-based compensation			(900,000)
Issuance of shares for employee stock plans and stock-based compensation, amount	(0.6)		$ (17.7)	(17.1)
Compensation expense associated with stock awards	9.5			9.5
Taxes paid related to net settlement of equity awards, shares			300,000
Taxes paid related to net share settlement of equity awards	(5.9)		$ (6.2)
Adjustments Related to Tax Withholding for Share-based Compensation	6.2
Other comprehensive loss	$ 15.1					15.1
Balance, Ending, Shares at Dec. 31, 2017	143,169,626	153,400,000	8,400,000
Balance, Ending at Dec. 31, 2017	$ 1,604.5	$ 153.4	$ (177.5)	470.6	1,280.1	(122.1)
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	(4.4)				12.3	(16.7)
Net income	394.6
Payment of cash dividends	(74.4)				(74.4)
Issuance of shares for employee stock plans and stock-based compensation			(1,000,000)
Issuance of shares for employee stock plans and stock-based compensation, amount	0.0		$ (21.0)	(21.0)
Treasury Stock, Shares, Acquired			8,600,000
Treasury Stock, Value, Acquired, Cost Method	(211.8)		$ (211.8)
Compensation expense associated with stock awards	8.6			8.6
Taxes paid related to net settlement of equity awards, shares			500,000
Taxes paid related to net share settlement of equity awards	(9.3)		$ (9.3)
Other comprehensive loss	$ (7.6)					(7.6)
Balance, Ending, Shares at Dec. 31, 2018	0	153,400,000	16,500,000
Balance, Ending at Dec. 31, 2018	$ 1,700.2	$ 153.4	$ (377.6)	$ 458.2	$ 1,612.6	$ (146.4)