Debt Maturities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Maturities [Abstract]
Debt maturities - 2014	$ 28,313
Debt maturities - 2015	24,866
Debt maturities - 2016	18,586
Debt maturities - 2017	11,844
Debt maturities 2018	6,094
Debt maturities - Thereafter	11,174
DebtAndCapitalLeaseObligationTotal	100,877
Total debt	100,990	98,693
Total unamortized discount	(77)	(87)
Total fair value adjustments	190	103
Unsecured Debt [Member]
Debt Maturities [Abstract]
Debt maturities - 2014	13,013
Debt maturities - 2015	9,961
Debt maturities - 2016	9,293
Debt maturities - 2017	7,298
Debt maturities 2018	5,596
Debt maturities - Thereafter	10,556
Total debt	55,717
Asset-backed Securities [Member]
Debt Maturities [Abstract]
Debt maturities - 2014	15,300
Debt maturities - 2015	14,905
Debt maturities - 2016	9,293
Debt maturities - 2017	4,546
Debt maturities 2018	498
Debt maturities - Thereafter	618
Total debt	45,160
Short-term debt [Member]
Debt Maturities [Abstract]
Debt maturities - 2014	12,668
Debt maturities - 2015	1,144
Long-term debt [Member]
Debt Maturities [Abstract]
Debt maturities - 2014	15,645
Debt maturities - 2015	23,722
Unsecured Debt Maturing Primarily by 2024 [Member]
Debt Maturities [Abstract]
Debt maturities - Thereafter	$ 10,540