Fair value measurements (Details 4) (USD $) In Millions	3 Months Ended
Dec. 31, 2010
License agreements
Definite-Lived and Indefinite Lived Intangible Assets. [Line Items]
Impairment charges	$ 67
Game engines
Definite-Lived and Indefinite Lived Intangible Assets. [Line Items]
Impairment charges	9
Internally developed franchises
Definite-Lived and Indefinite Lived Intangible Assets. [Line Items]
Impairment charges	$ 250

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 46
-Subparagraph b

Name:	us-gaap_ImpairmentOfIntangibleAssetsFinitelived
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration