Consolidated Statements of Changes in Shareholders Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Stockholders' Equity, Total [Member]	Treasury Stock, Common [Member]	AOCI Including Portion Attributable to Noncontrolling Interest
Treasury Stock, Value	$ (1,580.9)
Balance, shares at Dec. 31, 2017		114,447,605
Balance at Dec. 31, 2017		$ 1.1	$ 1,086.9	$ (128.5)	$ 2,422.4	$ 1,801.0
Net (loss) income	617.0					617.0
Impact on Retained Earnings, Adoption of ASC 606	(277.0)					(277.0)
Dividends, Common Stock, Cash	(49.2)					(49.2)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		466,719
Employee equity awards, value			27.4			27.4
Stock forfeitures, shares		47,962
Net shares settled		177,812
Payment, Tax Withholding, Share-based Payment Arrangement	15.6		(15.6)			15.6
Stock Issued During Period, Shares, Employee Stock Purchase Plans		24,996
Stock Issued During Period, Value, Employee Stock Purchase Plan			2.1			2.1
Treasury Stock, Shares, Acquired		(9,251,729)
Treasury Stock, Value, Acquired, Cost Method			0.1			(800.0)	$ (800.1)
Other Comprehensive Income	(68.1)			(68.1)		(68.1)
Balance, shares at Dec. 31, 2018		105,461,817
Balance at Dec. 31, 2018		$ 1.1	1,100.9	(196.6)	2,713.2	1,237.6
Treasury Stock, Value	(2,381.0)
Net (loss) income	530.1				530.1	530.1
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect					8.3	0.0		$ (8.3)
Dividends, Common Stock, Cash					(50.3)	(50.3)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		448,594
Employee equity awards, value			34.4			34.4
Stock forfeitures, shares		125,055
Net shares settled		137,500
Payment, Tax Withholding, Share-based Payment Arrangement	12.9		12.9			12.9
Stock Issued During Period, Shares, Employee Stock Purchase Plans		32,341
Stock Issued During Period, Value, Employee Stock Purchase Plan			2.6			2.6
Treasury Stock, Shares, Acquired		(804,032)
SERP shares issued		6,214
Supplemental Retirement Plan Shares Issued Value			0.0			0.0
Treasury Stock, Value, Acquired, Cost Method			0.0				(75.8)
Stock Repurchased During Period, Value						(75.8)
Other Comprehensive Income	95.7					95.7		$ 95.7
Balance, shares at Dec. 31, 2019		104,882,379
Balance at Dec. 31, 2019	1,761.4	$ 1.1	1,125.0	(109.2)	3,201.3	1,761.4
Treasury Stock, Value	(2,456.8)
Net (loss) income	(870.3)				(870.3)	(870.3)
Dividends, Common Stock, Cash	(4.4)				(4.4)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		952,392
Employee equity awards, value			26.7			26.7
Stock forfeitures, shares		192,111
Net shares settled		224,964
Payment, Tax Withholding, Share-based Payment Arrangement	14.5		14.5			14.5
Treasury Stock, Shares, Acquired		0
SERP shares issued		124,466
Supplemental Retirement Plan Shares Issued Value	2.6		2.6
Treasury Stock, Value, Acquired, Cost Method			0.0				$ 0.1
Stock Repurchased During Period, Value						0.1
Other Comprehensive Income	(44.9)					(44.9)
Balance, shares at Dec. 31, 2020		105,542,162
Balance at Dec. 31, 2020	856.5	$ 1.1	$ 1,139.8	$ (154.1)	2,326.4	856.5
Other retained earnings					$ (0.2)	$ (0.2)
Treasury Stock, Value	$ (2,456.7)