Balance Sheet Details - Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Property, Plant and Equipment [Line Items]
Property and equipment	$ 128.8	$ 107.6
Accumulated depreciation and amortization	(67.6)	(57.8)
Total property and equipment, net	61.2	49.8
Depreciation expense	12.1	12.3	$ 12.5
Land and buildings
Property, Plant and Equipment [Line Items]
Property and equipment	12.1	12.2
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment	30.1	26.9
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	49.9	47.2
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	5.7	5.3
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	11.2	9.9
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 19.8	$ 6.1