Discontinued Operations - Results of Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2018	Mar. 26, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense	$ 0.4	$ (0.2)
Income (loss) from discontinued operations	(3.5)	0.1
Herley | Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	23.9	36.8
Cost of sales	18.9	27.8
Selling, general and administrative expenses	8.1	8.7
Other expense	0.8	0.0
Income (loss) from discontinued operations before income taxes	(3.9)	0.3
Income tax expense	0.4	(0.2)
Income (loss) from discontinued operations	$ (3.5)	$ 0.1