CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Income Statement [Abstract]
Service revenues	$ 346.4	$ 348.1	$ 354.2
Product sales	405.5	320.6	302.9
Total revenues	751.9	668.7	657.1
Cost of service revenues	247.5	255.8	266.5
Cost of product sales	307.1	259.3	228.8
Total costs	554.6	515.1	495.3
Gross profit	197.3	153.6	161.8
Selling, general and administrative expenses	160.6	146.3	150.7
Merger and acquisition related items	0.0	1.9	0.1
Research and development expenses	17.8	13.9	16.2
Impairment of goodwill	24.2	0.0	0.0
Unused office space and other restructuring	0.5	10.1	(0.7)
Operating loss from continuing operations	(5.8)	(18.6)	(4.5)
Other income (expense):
Interest expense, net	(28.6)	(34.7)	(36.0)
Gain (loss) on extinguishment of debt	(17.3)	0.2	(3.4)
Other income (expense), net	0.9	0.8	(0.7)
Total other expense, net	(45.0)	(33.7)	(40.1)
Loss from continuing operations before income taxes	(50.8)	(52.3)	(44.6)
Provision (benefit) for income taxes from continuing operations	(8.2)	8.1	(11.4)
Income (loss) from continuing operations	(42.6)	(60.4)	(33.2)
Income (loss) from operations of discontinued component (including gain on disposal of $80.8 million for the year ended December 27, 2015)	0.0	(0.1)	75.5
Income tax expense	0.1	0.0	22.5
Income (loss) from discontinued operations	(0.1)	(0.1)	53.0
Net income (loss)	$ (42.7)	$ (60.5)	$ 19.8
Basic income and loss per common share:
Loss from continuing operations (in dollars per share)	$ (0.48)	$ (0.99)	$ (0.56)
Income (loss) from discontinued operations (in dollars per share)	0.00	0.00	0.90
Net income (loss) per common share (in dollars per share)	(0.48)	(0.99)	0.34
Diluted income and loss per common share:
Loss from continuing operations (in dollars per share)	(0.48)	(0.99)	(0.56)
Income (loss) from discontinued operations (in dollars per share)	0.00	0.00	0.90
Net income (loss) per common share (in dollars per share)	$ (0.48)	$ (0.99)	$ 0.34
Weighted average common shares outstanding:
Basic (in shares)	89.5	61.3	58.7
Diluted (in shares)	89.5	61.3	58.7
Comprehensive Income (Loss)
Net income (loss)	$ (42.7)	$ (60.5)	$ 19.8
Other comprehensive income (loss):
Change in cumulative translation adjustment	0.1	(0.5)	0.1
Postretirement benefit reserve adjustment net of tax expense	0.2	0.2	0.2
Other comprehensive income (loss), net of tax	0.3	(0.3)	0.3
Comprehensive income (loss)	$ (42.4)	$ (60.8)	$ 20.1