Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Portion at Other than Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	$ 364	$ 344
Customer financing notes receivable	309	283
Short-term borrowings	1,725	2,364
Long-term debt (excluding finance leases)	44,510	41,199
Long-term liabilities	339	336
Short-term borrowings	1,725	2,364
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	360	347
Customer financing notes receivable	283	283
Short-term borrowings	1,725	2,364
Long-term debt (excluding finance leases)	47,738	46,202
Long-term liabilities	328	322
Fair Value Level 1 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	0	0
Customer financing notes receivable	0	0
Short-term borrowings	0	0
Long-term debt (excluding finance leases)	0	0
Long-term liabilities	0	0
Fair Value Level 2 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	360	347
Customer financing notes receivable	283	283
Short-term borrowings	500	0
Long-term debt (excluding finance leases)	44,642	45,802
Long-term liabilities	328	322
Fair Value Level 3 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term receivables	0	0
Customer financing notes receivable	0	0
Short-term borrowings	1,225	2,364
Long-term debt (excluding finance leases)	3,096	400
Long-term liabilities	0	0
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	52	57
Derivative assets	137	56
Derivative liabilities	(594)	(287)
Fair Value, Recurring [Member] | Fair Value Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	52	57
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, 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	137	56
Derivative liabilities	(594)	(287)
Fair Value, 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