Statement of Consolidated Stockholders' Equity (Unaudited) - USD ($) $ in Millions		Total	Common Stock	Additional Paid in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment		$ 10.1			$ 10.5	$ 0.0	$ (0.4)
Adjusted balance		756.4	$ 0.2	$ 1,055.9	96.0	(358.6)	(37.1)
Beginning balance (shares) at Dec. 31, 2017			16,773,586
Beginning balance at Dec. 31, 2017		746.3	$ 0.2	1,055.9	85.5	(358.6)	(36.7)
Stockholders' Equity [Roll Forward]
Net income		25.7			25.7
Other comprehensive income, net of tax		(8.3)					(8.3)
Issuance of common shares to employees upon vesting of restricted stock units and performance shares (shares)			135,134
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (shares)			(68,029)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		$ (6.9)		(6.9)
Repurchase of common stock (shares)		(58,155)	(58,155)
Repurchase of common stock		$ (6.1)				(6.1)
Cash dividends on common stock and restricted shares and dividend equivalents on restricted stock units and performance shares1	[1]	(10.0)			(10.0)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition		2.8		2.8
Ending balance (shares) at Mar. 31, 2018			16,782,536
Ending balance at Mar. 31, 2018		$ 753.6	$ 0.2	1,051.8	111.7	(364.7)	(45.4)
Stockholders' Equity [Roll Forward]
Cash dividends declared (in dollars per share)		$ 0.55
Beginning balance (shares) at Dec. 31, 2018		16,234,603	16,234,603
Beginning balance at Dec. 31, 2018		$ 740.4	$ 0.2	1,059.3	150.2	(420.5)	(48.8)
Stockholders' Equity [Roll Forward]
Net income		28.0			28.0
Other comprehensive income, net of tax		9.7					9.7
Issuance of common shares to employees upon vesting of restricted stock units and performance shares (shares)			122,309
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (shares)			(46,388)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		$ (5.0)		(5.0)
Repurchase of common stock (shares)		(175,977)	(175,977)
Repurchase of common stock		$ (17.4)				(17.4)
Cash dividends on common stock and restricted shares and dividend equivalents on restricted stock units and performance shares1	[2]	(10.2)			(10.2)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition		$ 2.4		2.4
Ending balance (shares) at Mar. 31, 2019		16,134,547	16,134,547
Ending balance at Mar. 31, 2019		$ 747.9	$ 0.2	$ 1,056.7	$ 168.0	$ (437.9)	$ (39.1)
Stockholders' Equity [Roll Forward]
Cash dividends declared (in dollars per share)		$ 0.60

[1] Dividends declared per common share were $0.55 during the quarter ended March 31, 2018.

[2] Dividends declared per common share were $0.60 during the quarter ended March 31, 2019.