Summary of Significant Accounting Policies - Transaction Price Allocated to Remaining Performance Obligations (Details) $ in Millions	3 Months Ended
	Mar. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 19.7
Revenue, remaining performance obligation, expected timing of satisfaction, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 13.7
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Fixed-price [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 5.5
Managed-support Contracts [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 27.9