Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term borrowings	$ 871	$ 926
Portion at Other than Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	136	122
Customer financing notes receivable	459	403
Short-term borrowings	871	926
Long-term debt (excluding capitalized leases)	21,774	19,476
Long-term liabilities	427	458
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	129	107
Customer financing notes receivable	430	403
Short-term borrowings	871	926
Long-term debt (excluding capitalized leases)	24,938	21,198
Long-term liabilities	397	419
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	129
Customer financing notes receivable	430
Short-term borrowings	780
Long-term debt (excluding capitalized leases)	24,752
Long-term liabilities	397
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	91
Long-term debt (excluding capitalized leases)	186
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	1,005	951
Derivative Assets	101	101
Derivative Liabilities	181	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	1,005	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	101	101
Derivative Liabilities	181	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