CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle	$ 0.0			$ 0.2		$ (0.2)
Balance (in shares) at Dec. 31, 2018		41,065,069			21,719,339
Balance at Dec. 31, 2018	473.2	$ 0.4	$ 572.9	922.7	$ (1,023.4)	0.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40.9			40.9
Change in fair value of cash flow swaps, net of reclassification adjustment	(1.3)					(1.3)
Other comprehensive income	39.6			40.9		(1.3)
Share-based compensation	3.9		3.9
Issuance of common stock, net of forfeitures in connection with share-based payment arrangements (in shares)		(238,078)
Issuance of common stock, net of forfeitures in connection with share-based payment arrangements	0.0
Repurchase of common stock associated with net share settlements of employee share-based awards (in shares)					66,912
Repurchase of common stock associated with net share settlements of employee share-based awards	(4.7)				$ (4.7)
Share repurchases (in shares)					108,978
Share repurchases	(7.4)				$ (7.4)
Retirement of previously repurchased common stock (in shares)		(108,978)			(108,978)
Retirement of previously repurchased common stock	0.0		(1.3)	(6.1)	$ 7.4
Balance (in shares) at Mar. 31, 2019		41,194,169			21,786,251
Balance at Mar. 31, 2019	504.6	$ 0.4	575.5	957.7	$ (1,028.1)	(0.9)
Balance (in shares) at Dec. 31, 2019		41,072,080			21,791,707
Balance at Dec. 31, 2019	646.3	$ 0.4	582.9	1,094.5	$ (1,028.6)	(2.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	19.5			19.5
Change in fair value of cash flow swaps, net of reclassification adjustment	(3.4)					(3.4)
Other comprehensive income	(3.4)			0.0		(3.4)
Share-based compensation	3.8		3.8
Issuance of common stock, net of forfeitures in connection with share-based payment arrangements (in shares)		(68,577)
Issuance of common stock, net of forfeitures in connection with share-based payment arrangements	(0.3)		(0.3)
Repurchase of common stock associated with net share settlements of employee share-based awards (in shares)					53,915
Repurchase of common stock associated with net share settlements of employee share-based awards	(5.0)				$ 5.0
Balance (in shares) at Mar. 31, 2020		41,140,657			21,845,622
Balance at Mar. 31, 2020	$ 660.9	$ 0.4	$ 586.4	$ 1,114.0	$ (1,033.6)	$ (6.3)