Quarterly Financial Data (Unaudited) Summarized Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jun. 25, 2017	Mar. 26, 2017	Dec. 30, 2018	Dec. 31, 2017	Dec. 25, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 164.4	$ 159.4	$ 151.2	$ 143.0	$ 166.3	$ 157.1	$ 147.9	$ 132.0	$ 618.0	$ 603.3	$ 541.9
Gross profit	45.5	44.1	39.3	40.8	46.8	37.2	37.5	36.1	169.7	157.6	120.5
Total operating income (loss) from continuing operations	10.8	10.1	2.6	7.0	(15.0)	0.1	1.5	1.4	30.5	(12.0)	(18.0)
Provision (benefit) for income taxes from continuing operations	0.2	3.4	0.1	0.9	(11.8)	(1.1)	1.3	1.4	4.6	(10.2)	5.8
Income (loss) from continuing operations	5.2	1.4	(3.8)	1.3	(24.0)	(5.9)	(6.9)	(10.1)
Income (loss) from discontinued operations	(0.5)	0.3	(3.9)	(3.5)	1.8	1.6	0.7	0.1
Net income (loss)	$ 4.7	$ 1.7	$ (7.7)	$ (2.2)	$ (22.2)	$ (4.3)	$ (6.2)	$ (10.0)	$ (3.5)	$ (42.7)	$ (60.5)
Basic income (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	$ 0.05	$ 0.01	$ (0.04)	$ 0.01	$ (0.23)	$ (0.07)	$ (0.08)	$ (0.13)	$ 0.04	$ (0.52)	$ (0.94)
Income (loss) from discontinued operations (in dollars per share)	0.00	0.01	(0.03)	(0.03)	0.02	0.02	0.01	0.00	(0.07)	0.04	(0.05)
Net income (loss) per common share (in dollars per share)	0.05	0.02	(0.07)	(0.02)	(0.21)	(0.05)	(0.07)	(0.13)	(0.03)	(0.48)	(0.99)
Diluted income (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	0.05	0.01	(0.04)	0.01	(0.23)	(0.07)	(0.08)	(0.13)	0.04	(0.52)	(0.94)
Income (loss) from discontinued operations (in dollars per share)	(0.01)	0.01	(0.03)	(0.03)	0.02	0.02	0.01	0.00	(0.07)	0.04	(0.05)
Net income (loss) per common share (in dollars per share)	$ 0.04	$ 0.02	$ (0.07)	$ (0.02)	$ (0.21)	$ (0.05)	$ (0.07)	$ (0.13)	$ (0.03)	$ (0.48)	$ (0.99)