Fair Value Measurements Nonrecurring Fair Value Changes (Details) (Financial Services [Member], Fair Value, Measurements, Nonrecurring [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Items measured at fair value [Line Items]
Total Gains / (Losses)	$ (12)	$ (11)	$ (25)	$ (30)
North America [Member]
Items measured at fair value [Line Items]
Total Gains / (Losses)	(6)	(8)	(14)	(19)
International [Member]
Items measured at fair value [Line Items]
Total Gains / (Losses)	(6)	(3)	(11)	(11)
Retail [Member] | North America [Member]
Items measured at fair value [Line Items]
Total Gains / (Losses)	(6)	(8)	(14)	(19)
Retail [Member] | International [Member]
Items measured at fair value [Line Items]
Total Gains / (Losses)	(6)	(3)	(11)	(11)
Dealer loans [Member] | North America [Member]
Items measured at fair value [Line Items]
Total Gains / (Losses)	$ 0	$ 0	$ 0	$ 0