Commitments and Contingencies Contract Cancellations and Noncancelable Operating Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Contract Cancellation [Line Items]
Loss on Contract Termination	$ 137	$ 93	$ 33
Favorable Changes to Estimated Cancellation Charges			30
Future Minimum Payments, 2013	394
Future Minimum Payments, 2014	312
Future Minimum Payments, 2015	246
Future Minimum Payments, 2016	192
Future Minimum Payments, 2017	125
Future Minimum Payments, Thereafter	595
Operating Leases, Rent Expense, Net	474	556	604
2013 [Member]
Contract Cancellation [Line Items]
Sublease Income	(54)
Net Minimum Commitment on Operating Lease	340
2014 [Member]
Contract Cancellation [Line Items]
Sublease Income	(53)
Net Minimum Commitment on Operating Lease	259
2015 [Member]
Contract Cancellation [Line Items]
Sublease Income	(48)
Net Minimum Commitment on Operating Lease	198
2016 [Member]
Contract Cancellation [Line Items]
Sublease Income	(47)
Net Minimum Commitment on Operating Lease	145
2017 [Member]
Contract Cancellation [Line Items]
Sublease Income	(45)
Net Minimum Commitment on Operating Lease	80
2018 and after [Member]
Contract Cancellation [Line Items]
Sublease Income	(279)
Net Minimum Commitment on Operating Lease	316
GMNA [Member]
Contract Cancellation [Line Items]
Loss on Contract Termination	64	38	30
GME [Member]
Contract Cancellation [Line Items]
Loss on Contract Termination	38	8	3
GMIO [Member]
Contract Cancellation [Line Items]
Loss on Contract Termination	5	43	0
GMSA [Member]
Contract Cancellation [Line Items]
Loss on Contract Termination	$ 30	$ 4	$ 0