Income Taxes (Narrative) (Details) DKK in Millions, $ in Millions		3 Months Ended		12 Months Ended	36 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Apr. 01, 2016	Dec. 31, 2016	Dec. 31, 2012 DKK	Dec. 10, 2013 DKK
Income Tax Examination [Line Items]
Effective income tax rate, percent		17.30%	25.20%
Federal statutory income tax rate, percent		35.00%		35.00%
Effective income tax rate reconciliation,other reconciling items, percent		(3.20%)
Effective income tax rate reconciliation, gain on sale of marketable equity securities, percent			4.90%
Denmark, kroner | Foreign tax authority
Income Tax Examination [Line Items]
Income tax examination, amount of tax assessments | DKK						DKK 1,400
Income tax examination, amount of potential additional tax assessments | DKK					DKK 833
United States of America, dollars | Foreign tax authority
Income Tax Examination [Line Items]
Income tax examination, amount of tax assessments | $	$ 203	$ 203
Income tax examination, amount of potential additional tax assessments | $	$ 120