CONDENSED CONSOLIDATED STATEMENTS OF TOTAL EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Treasury Stock	Total Shareholders' Equity	Non-controlling Interest
BALANCE, beginning of period (in shares) at Dec. 31, 2017		16.7
BALANCE, beginning of period at Dec. 31, 2017	$ 302.1	$ 0.0	$ 319.0	$ (13.8)	$ (24.8)	$ 280.4	$ 21.7
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	2.2		2.2			2.2
Treasury share purchases	(1.2)				(1.2)	(1.2)
Net income (loss)	(3.9)			(3.9)		(3.9)
Restricted stock grants, net of cancellations (in shares)		0.1
Restricted stock grants, net of cancellations	0.0
Measurement period adjustments for prior year business combinations	(0.1)						(0.1)
BALANCE, end of period (in shares) at Mar. 31, 2018		16.8
BALANCE, end of period at Mar. 31, 2018	299.1	$ 0.0	321.2	(17.7)	(26.0)	277.5	21.6
BALANCE, beginning of period (in shares) at Dec. 31, 2017		16.7
BALANCE, beginning of period at Dec. 31, 2017	302.1	$ 0.0	319.0	(13.8)	(24.8)	280.4	21.7
Increase (Decrease) in Stockholders' Equity
Net income (loss)	28.2
BALANCE, end of period (in shares) at Sep. 30, 2018		16.8
BALANCE, end of period at Sep. 30, 2018	336.5	$ 0.0	327.1	14.2	(26.6)	314.7	21.8
BALANCE, beginning of period (in shares) at Mar. 31, 2018		16.8
BALANCE, beginning of period at Mar. 31, 2018	299.1	$ 0.0	321.2	(17.7)	(26.0)	277.5	21.6
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	3.0		3.0			3.0
Treasury share purchases	(0.6)				(0.6)	(0.6)
Net income (loss)	16.3			16.3		16.3
BALANCE, end of period (in shares) at Jun. 30, 2018		16.8
BALANCE, end of period at Jun. 30, 2018	317.8	$ 0.0	324.2	(1.4)	(26.6)	296.2	21.6
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	2.9		2.9			2.9
Net income (loss)	15.8			15.6		15.6	0.2
BALANCE, end of period (in shares) at Sep. 30, 2018		16.8
BALANCE, end of period at Sep. 30, 2018	336.5	$ 0.0	327.1	14.2	(26.6)	314.7	21.8
BALANCE, beginning of period (in shares) at Dec. 31, 2018		16.6
BALANCE, beginning of period at Dec. 31, 2018	337.2	$ 0.0	329.6	16.2	(33.4)	312.4	24.8
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	1.7		1.7			1.7
Stock options exercised	0.2		0.2			0.2
Treasury share purchases	(1.1)				(1.1)	(1.1)
Net income (loss)	(2.6)			(2.7)		(2.7)	0.1
BALANCE, end of period (in shares) at Mar. 31, 2019		16.6
BALANCE, end of period at Mar. 31, 2019	335.4	$ 0.0	331.5	13.5	(34.5)	310.5	24.9
BALANCE, beginning of period (in shares) at Dec. 31, 2018		16.6
BALANCE, beginning of period at Dec. 31, 2018	337.2	$ 0.0	329.6	16.2	(33.4)	312.4	24.8
Increase (Decrease) in Stockholders' Equity
Net income (loss)	11.9
BALANCE, end of period (in shares) at Sep. 30, 2019		16.7
BALANCE, end of period at Sep. 30, 2019	363.5	$ 0.0	346.2	27.2	(35.6)	337.8	25.7
BALANCE, beginning of period (in shares) at Mar. 31, 2019		16.6
BALANCE, beginning of period at Mar. 31, 2019	335.4	$ 0.0	331.5	13.5	(34.5)	310.5	24.9
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	9.4		9.4			9.4
Treasury share purchases	(1.1)				1.1	(1.1)
Net income (loss)	0.9			0.7		0.7	0.2
Restricted stock vesting (in shares)		0.1
Restricted stock vesting	0.0
BALANCE, end of period (in shares) at Jun. 30, 2019		16.7
BALANCE, end of period at Jun. 30, 2019	344.6	$ 0.0	340.9	14.2	(35.6)	319.5	25.1
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	5.3		5.3			5.3
Net income (loss)	13.6			13.0		13.0	0.6
BALANCE, end of period (in shares) at Sep. 30, 2019		16.7
BALANCE, end of period at Sep. 30, 2019	$ 363.5	$ 0.0	$ 346.2	$ 27.2	$ (35.6)	$ 337.8	$ 25.7