Defined Pension Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jul. 02, 2017	Jul. 02, 2017	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to defined benefit pension plan		$ 0.8
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to defined benefit pension plan	$ 0.4
Minimum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to defined benefit pension plan			$ 0.4
Maximum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to defined benefit pension plan			$ 0.8