Contingencies and commitments (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Contingencies and Commitments (Textual) [Abstract]
Future rental commitments for abandoned leases		$ 254
Rental expense on operating leases		131	115	114
Minimum contractual purchase commitments with third party manufacturers through 2014		157
Purchases under contractual purchase commitments		87	68	207
Legal settlement charge associated with proposed settlement of allegations	$ (780)	$ (780)

The net proceeds or assets obtained in excess of (less than) the net carrying amount of assets recorded, or assets distributed and liabilities assumed less than (in excess of) estimated litigation liability extinguished, in settlement of a litigation matter. Represents (for other than an insurance entity in its normal claims settlement process), the amount of income (expense) recognized in the period to settle pending or threatened litigation and insurance claims.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Name:	us-gaap_GainLossRelatedToLitigationSettlement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration