Indebtedness (Details Textual) SFr in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Dec. 31, 2008 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 CHF (SFr)	Mar. 04, 2008 USD ($)	Dec. 31, 2006 CHF (SFr)
Debt Instrument
Net charge upon extinguishment of debt		$ 5,200,000
Payment for debt extinguishment		7,700,000
Costs associated with the Senior Notes offerings					$ 47,500,000
Redemptions percentage of 2015 notes				100.00%
Redemption percentage for change in control provision on the 2015 Senior Notes				101.00%
Notes payable and other financing arrangements		6,003,200,000		$ 6,003,200,000
Senior unsecured revolving credit facility maximum borrowing capacity					$ 1,000,000,000
Term of credit facility					5 years
Amount outstanding under the credit facility		$ 0		$ 0
6.875% Senior Notes due 2018
Debt Instrument
Interest rate on senior notes		6.875%		6.875%		6.875%			6.875%
Redemption percentage par value of senior notes									99.184%
Increased carrying amount of interest rate swap	$ 62,800,000
Senior Notes aggregate principal amount									$ 550,000,000
Notes payable and other financing arrangements		$ 0		$ 0			$ 558,500,000
2.90% Senior Notes due 2020
Debt Instrument
Interest rate on senior notes		2.90%		2.90%	2.90%	2.90%
Redemption percentage par value of senior notes					99.792%
Senior Notes aggregate principal amount					$ 1,500,000,000
Notes payable and other financing arrangements		$ 1,482,400,000		$ 1,482,400,000			1,485,300,000
3.625% Senior Notes due 2022
Debt Instrument
Interest rate on senior notes		3.625%		3.625%	3.625%	3.625%
Redemption percentage par value of senior notes					99.92%
Senior Notes aggregate principal amount					$ 1,000,000,000
Notes payable and other financing arrangements		$ 994,300,000		$ 994,300,000			993,200,000
4.05% Senior Notes due 2025
Debt Instrument
Interest rate on senior notes		4.05%		4.05%	4.05%	4.05%
Redemption percentage par value of senior notes					99.764%
Senior Notes aggregate principal amount					$ 1,750,000,000
Notes payable and other financing arrangements		$ 1,736,300,000		$ 1,736,300,000			1,734,800,000
5.20% Senior Notes due 2045
Debt Instrument
Interest rate on senior notes		5.20%		5.20%	5.20%	5.20%
Redemption percentage par value of senior notes					99.294%
Senior Notes aggregate principal amount					$ 1,750,000,000
Notes payable and other financing arrangements		$ 1,722,000,000		$ 1,722,000,000			1,721,500,000
Note payable to Fumedica
Debt Instrument
Notes payable and other financing arrangements		0		0			3,000,000			SFr 61.4
Par value of notes payable		3,200,000		3,200,000		SFr 3.1	$ 6,000,000	SFr 6.2
Interest rate swap
Debt Instrument
Net charge upon extinguishment of debt		2,900,000
Interest rate swap | 2.90% Senior Notes due 2020
Debt Instrument
Fair value of the interest rate swaps		10,100,000		$ 10,100,000
Eisai
Debt Instrument
Facility purchase		$ 17,200,000	$ 104,800,000