Income Taxes - Operating Loss and Tax Credit Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 29, 2018 USD ($)
Operating loss and tax credit carryforwards
Undistributed earnings of foreign subsidiaries	$ 105.0
Provision for foreign withholding tax and state income taxes	0.0
State
Operating loss and tax credit carryforwards
Operating loss carryforwards	43.8
State | Tentative minimum tax credit
Operating loss and tax credit carryforwards
Tax credit carryforwards	0.1
State | Research and development tax credit
Operating loss and tax credit carryforwards
Tax credit carryforwards	13.5
Silicon Clocks, Spectra Linear and Ember | Federal
Operating loss and tax credit carryforwards
Operating loss carryforwards	32.7
Tax credit carryforwards	1.9
Energy Micro | Foreign
Operating loss and tax credit carryforwards
Operating loss carryforwards	$ 1.9