Organization and Summary of Significant Accounting Policies - Operating Income from Continuing Operations (Details) - USD ($) $ 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
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 164.4	$ 159.4	$ 151.2	$ 143.0	$ 166.3	$ 157.1	$ 147.9	$ 132.0	$ 618.0	$ 603.3	$ 541.9
Total costs									448.3	445.7	421.4
Gross profit	45.5	44.1	39.3	40.8	46.8	37.2	37.5	36.1	169.7	157.6	120.5
Selling, general and administrative expenses									119.8	127.3	114.6
Operating income 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)
Service
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									200.7	197.8	221.3
Total costs									137.8	138.6	162.1
Product
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									417.3	405.5	320.6
Total costs									310.5	$ 307.1	$ 259.3
Balances Without Adoption of ASC 606 | ASC 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									588.0
Total costs									426.4
Gross profit									161.6
Selling, general and administrative expenses									119.8
Operating income from continuing operations									22.4
Balances Without Adoption of ASC 606 | ASC 606 | Service
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									200.7
Total costs									137.8
Balances Without Adoption of ASC 606 | ASC 606 | Product
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									387.3
Total costs									288.6
Effect of Change Higher/(Lower)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									30.0
Effect of Change Higher/(Lower) | ASC 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									30.0
Total costs									21.9
Gross profit									8.1
Selling, general and administrative expenses									0.0
Operating income from continuing operations									8.1
Effect of Change Higher/(Lower) | ASC 606 | Service
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									0.0
Total costs									0.0
Effect of Change Higher/(Lower) | ASC 606 | Product
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues									30.0
Total costs									$ 21.9