Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	$ 122	$ 107
Customer financing notes receivable	433	403
Short Term borrowings	1,233	926
Long-term debt (excluding capitalized leases)	24,219	21,198
Long-term liabilities	428	419
Portion at Other than Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	129	122
Customer financing notes receivable	456	403
Short Term borrowings	1,233	926
Long-term debt (excluding capitalized leases)	21,795	19,476
Long-term liabilities	429	458
Fair Value Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	0
Customer financing notes receivable	0
Short Term borrowings	0
Long-term debt (excluding capitalized leases)	0
Long-term liabilities	0
Fair Value Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	122
Customer financing notes receivable	433
Short Term borrowings	1,073
Long-term debt (excluding capitalized leases)	23,961
Long-term liabilities	428
Fair Value Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	0
Customer financing notes receivable	0
Short Term borrowings	160
Long-term debt (excluding capitalized leases)	258
Long-term liabilities	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,083	951
Derivative Assets	96	101
Derivative Liabilities	311	533
Fair Value, Measurements, Recurring [Member] | Fair Value Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,083	951
Derivative Assets	0	0
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Derivative Assets	96	101
Derivative Liabilities	311	533
Fair Value, Measurements, Recurring [Member] | Fair Value Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 0