Income Taxes (Narrative) (Details) $ / shares in Units, kr in Millions, $ in Millions			3 Months Ended	9 Months Ended		12 Months Ended		36 Months Ended
	Sep. 28, 2018 USD ($)	Dec. 31, 2017	Sep. 28, 2018 USD ($) $ / shares	Sep. 28, 2018 USD ($) $ / shares	Sep. 29, 2017	Dec. 31, 2017 USD ($)	Dec. 21, 2017	Dec. 31, 2012 DKK (kr)	Dec. 10, 2013 DKK (kr)
Income Tax Examination [Line Items]
Federal statutory income tax rate, percent		21.00%					35.00%
Effective income tax rate reconciliation, other reconciling items, amount			$ 23	$ 9
Effective income tax rate reconciliation, other reconciling items, per diluted share amount | $ / shares			$ 0.03	$ 0.01
Effective income tax rate reconciliation, other reconciling items, percent			2.90%		(3.30%)
TCJA, transition tax, provisional tax liability						$ 1,200
TCJA, transition tax, provisional tax liability, term						8 years
TCJA, income tax benefit						$ 1,200
Foreign tax authority
Income Tax Examination [Line Items]
Income tax examination, amount of tax assessments	$ 247		$ 247	$ 247					kr 1,600
Income tax examination, amount of potential additional tax assessments	$ 146							kr 939