Condensed Consolidated Statement of Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained (Deficit) Earnings	Accumulated Other Comprehensive Income
Beginning Balance (in shares) at Dec. 31, 2018		37,335,000
Beginning Balance at Dec. 31, 2018	$ 137.7	$ 0.4	$ 187.0	$ (25.1)	$ (27.6)	$ 3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	1.5		1.5
Issuance of restricted stock (in shares)		103,000
Issuance of restricted stock	0.0		(1.8)	1.8
Stock withheld for employee taxes (in shares)		(34,000)
Stock withheld for employee taxes	(0.8)			(0.8)
Proceeds from issuance of common stock (in shares)		3,000
Proceeds from issuance of common stock	0.0
Issuance of shares under employee stock purchase plan (in shares)		21,000
Issuance of shares under employee stock purchase plan	0.4		0.4
Dividends	(4.5)				(4.5)
Net income	9.7				9.7
Ending Balance (in shares) at Mar. 31, 2019		37,428,000
Ending Balance at Mar. 31, 2019	144.0	$ 0.4	187.1	(24.1)	(22.4)	3.0
Beginning Balance (in shares) at Dec. 31, 2018		37,335,000
Beginning Balance at Dec. 31, 2018	137.7	$ 0.4	187.0	(25.1)	(27.6)	3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in cumulative translation adjustment	0.1
Net income	24.3
Ending Balance (in shares) at Jun. 30, 2019		37,486,000
Ending Balance at Jun. 30, 2019	156.1	$ 0.4	188.1	(23.2)	(12.3)	3.1
Beginning Balance (in shares) at Mar. 31, 2019		37,428,000
Beginning Balance at Mar. 31, 2019	144.0	$ 0.4	187.1	(24.1)	(22.4)	3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	1.3		1.3
Issuance of restricted stock (in shares)		6,000
Issuance of restricted stock	0.0
Stock withheld for employee taxes (in shares)		(1,000)
Stock withheld for employee taxes	0.0
Proceeds from issuance of common stock (in shares)		53,000
Proceeds from issuance of common stock	0.6		(0.3)	0.9
Dividends	(4.5)				(4.5)
Change in cumulative translation adjustment	0.1					0.1
Net income	14.6				14.6
Ending Balance (in shares) at Jun. 30, 2019		37,486,000
Ending Balance at Jun. 30, 2019	156.1	$ 0.4	188.1	(23.2)	(12.3)	3.1
Beginning Balance (in shares) at Dec. 31, 2019		37,679,000
Beginning Balance at Dec. 31, 2019	175.5	$ 0.4	189.7	(20.4)	2.8	3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	1.0		1.0
Issuance of restricted stock (in shares)		36,000
Issuance of restricted stock	0.0		(0.6)	0.6
Stock withheld for employee taxes (in shares)		(15,000)
Stock withheld for employee taxes	(0.3)			(0.3)
Proceeds from issuance of common stock (in shares)		30,000
Proceeds from issuance of common stock	0.3		(0.2)	0.5
Issuance of shares under employee stock purchase plan (in shares)		23,000
Issuance of shares under employee stock purchase plan	0.4		0.4
Dividends	(43.3)				(43.3)
Repurchase of treasury shares (in shares)		(233,000)
Repurchase of treasury shares	(3.9)			(3.9)
Change in cumulative translation adjustment	(0.2)					(0.2)
Net income	8.2				8.2
Ending Balance (in shares) at Mar. 31, 2020		37,520,000
Ending Balance at Mar. 31, 2020	137.7	$ 0.4	190.3	(23.5)	(32.3)	2.8
Beginning Balance (in shares) at Dec. 31, 2019		37,679,000
Beginning Balance at Dec. 31, 2019	$ 175.5	$ 0.4	189.7	(20.4)	2.8	3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of treasury shares (in shares)	(283,450)
Repurchase of treasury shares	$ (4.8)
Change in cumulative translation adjustment	(0.2)
Net income	24.6				24.6
Ending Balance (in shares) at Jun. 30, 2020		37,475,000
Ending Balance at Jun. 30, 2020	148.7	$ 0.4	191.0	(24.3)	(21.2)	2.8
Beginning Balance (in shares) at Mar. 31, 2020		37,520,000
Beginning Balance at Mar. 31, 2020	137.7	$ 0.4	190.3	(23.5)	(32.3)	2.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	0.8		0.8
Issuance of restricted stock (in shares)		5,000
Issuance of restricted stock	0.0		(0.1)	0.1
Dividends	$ (5.3)				(5.3)
Repurchase of treasury shares (in shares)	(50,201)	(50,000)
Repurchase of treasury shares	$ (0.9)			(0.9)
Change in cumulative translation adjustment	0.0
Net income	16.4				16.4
Ending Balance (in shares) at Jun. 30, 2020		37,475,000
Ending Balance at Jun. 30, 2020	$ 148.7	$ 0.4	$ 191.0	$ (24.3)	$ (21.2)	$ 2.8