Consolidated Statement of Shareholders' Equity. - USD ($) $ in Millions		Common Stock	Additional Paid-In Capital	Deferred Compensation Equity	Accumulated Other Comprehensive Income (loss).	Retained Earnings	Shares in Treasury	Total
Balance at the beginning of the period at Dec. 31, 2014		$ 78.7	$ 247.8	$ 6.0	$ (61.8)	$ 2,134.4	$ (200.1)	$ 2,205.0
Balance (in shares) at Dec. 31, 2014		64,691,059					13,723,201
Increase (Decrease) in Shareholders' Equity
Net income								39.4
Other comprehensive income (loss), net of tax					(20.0)			(20.0)
Cash dividends - $0.94 and $0.30 for the year ended 2015 and the three months ended March 31, 2016, respectively								(16.7)
Balance at the end of the period at Mar. 31, 2015					(81.8)
Balance at the beginning of the period at Dec. 31, 2014		$ 78.7	247.8	6.0	(61.8)	2,134.4	$ (200.1)	2,205.0
Balance (in shares) at Dec. 31, 2014		64,691,059					13,723,201
Increase (Decrease) in Shareholders' Equity
Net income						319.7		319.7
Other comprehensive income (loss), net of tax					(25.3)			(25.3)
Cash dividends - $0.94 and $0.30 for the year ended 2015 and the three months ended March 31, 2016, respectively						(72.3)		(72.3)
Common stock repurchase							$ (137.2)	(137.2)
Common stock repurchase (in Shares)		(1,496,411)					1,496,411
Stock based compensation (1)	[1]		45.6	2.0			$ 9.9	57.5
Stock based compensation (in shares)	[1]	856,952					(836,371)
Balance at the end of the period at Dec. 31, 2015		$ 78.7	293.4	8.0	(87.1)	2,381.8	$ (327.4)	$ 2,347.4
Balance (in shares) at Dec. 31, 2015		64,051,600					14,383,241	64,051,600
Increase (Decrease) in Shareholders' Equity
Net income						68.5		$ 68.5
Other comprehensive income (loss), net of tax					10.4			10.4
Cash dividends - $0.94 and $0.30 for the year ended 2015 and the three months ended March 31, 2016, respectively						(19.5)		(19.5)
Common stock repurchase							$ (28.5)	(28.5)
Common stock repurchase (in Shares)		(331,747)					331,747
Stock based compensation (1)	[1]		4.8	2.4			$ 2.0	9.2
Stock based compensation (in shares)	[1]	241,259					(242,182)
Balance at the end of the period at Mar. 31, 2016		$ 78.7	$ 298.2	$ 10.4	$ (76.7)	$ 2,430.8	$ (353.9)	$ 2,387.5
Balance (in shares) at Mar. 31, 2016		63,961,112					14,472,806	63,961,112

[1] Issuances for stock based compensation includes shares issued from treasury to cover stock option exercises, restricted and performance share releases, net of shares repurchased to cover employee taxes