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