Committments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2008	Apr. 30, 2012	Mar. 31, 2012	Sep. 30, 2011
Commitments [Abstract]
Increase In Minimum Rental Payments		$ 900
Period end lease indemnifications			600
Recorded liability for lease indemnifications			200
Cash payment for contingent consideration	150
Earnout payment additional claim				700
Escrow amount related to arrangement			13
Contingent liability for Harmonix			$ 383