Collaborative arrangements (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Research and Development Arrangement, Contract to Perform for Others [Line Items]
ENBREL sales	$ 3,907	$ 3,877	$ 3,893	$ 3,618	$ 3,760	$ 3,759	$ 3,613	$ 3,528	$ 15,295	$ 14,660	$ 14,351
Collaborative Arrangement with Pfizer Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Maximum percentage of annual net ENBREL sales payable to Pfizer for three years after expiration of the collaboration agreement in the fourth quarter of 2013	12.00%								12.00%
Minimum percentage of annual net ENBREL sales payable to Pfizer for three years after expiration of the collaboration agreement in the fourth quarter of 2013	10.00%								10.00%
ENBREL sales									3,700	3,500	3,500
Period required to pay percentage of net sales, after expiration of agreement in years									3 years
Collaborative Arrangement with Pfizer Inc [Member] | Selling, General and Administrative [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Profit share expenses									1,288	1,184	1,163
Cost recoveries									$ 84	$ 87	$ 75