Income Taxes (Narrative) (Details) $ / shares in Units, DKK in Millions, $ in Millions			12 Months Ended			36 Months Ended
	Jan. 01, 2018	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2012 DKK	Dec. 31, 2014 USD ($)	Dec. 10, 2013 DKK
Net deferred tax liabilities		$ 2,333.3	$ 2,333.3	$ 2,851.8
Valuation allowance, deferred tax asset, change in amount			18.0
Basis differences in investments outside the U.S.		8,000.0	$ 8,000.0
Statutory federal income tax rate			35.00%	35.00%	35.00%
TCJA, income tax benefit			$ (1,200.0)
TCJA, effect on income tax expense, transition tax			$ 1,200.0
Effective income tax rate			16.00%	17.50%	14.40%
Effective income tax rate reconciliation, other reconciling items, percent			(5.00%)	(3.50%)	(2.90%)
Income tax payments			$ 689.0	$ 767.0	$ 584.0
Employee service share-based compensation, tax benefit from exercise of stock options			85.0	99.0	147.0
Excess tax benefit from share-based compensation, financing activities			55.0	50.0	88.0
Net operating loss carryforwards		502.0	502.0
Operating loss carryforwards, valuation allowances		283.0	283.0
Deferred tax assets, valuation allowances		324.6	324.6	306.5
Gross unrecognized tax benefits		736.8	736.8	992.2	990.2		$ 728.5
Unrecognized tax benefits, net of offsetting indirect tax benefits				933.0
Unrecognized tax benefits, indirect tax benefits				179.0
Potential interest and penalties				(120.0)
Recognized potential interest and penalties			41.0	47.0	39.0
Unrecognized tax benefits that would impact effective tax rate		691.0	691.0
International
Cash		593.0	593.0
TCJA, cash equivalents		656.0	656.0
Entity | United States
Net deferred tax liabilities		2,000.0	2,000.0	2,500.0
Entity | International
Net deferred tax liabilities		301.0	301.0	374.0
Foreign tax authority
Income tax examination, amount of tax assessments		245.0	245.0					DKK 1,500
Income tax examination, amount of potential additional tax assessments		144.0				DKK 895
Income tax holiday, aggregate dollar amount			$ 62.0	$ 61.0	$ 33.0
Income tax holiday, income tax benefits per share | $ / shares			$ 0.09	$ 0.09	$ 0.05
Deferred tax asset, other
Deferred tax assets, valuation allowances		12.0	$ 12.0
Continuing operations
Gross unrecognized tax benefits		737.0	737.0
Unrecognized tax benefits, net of offsetting indirect tax benefits		736.0	736.0
Unrecognized tax benefits, indirect tax benefits		104.0	104.0
Potential interest and penalties		(103.0)	(103.0)
Estimated reduction in unrecognized tax benefits within twelve months		(130.0)	(130.0)
Continuing operations | General business and foreign tax credit
Tax credit carryforwards		171.0	171.0
Tax credit carryforward, valuation allowance		$ 30.0	$ 30.0
Scenario, forecast
Statutory federal income tax rate	21.00%