Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Jun. 30, 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]
Customer financing notes receivable	$ 281	$ 220
Short-term borrowings	(243)	(2,293)
Long-term debt (excluding finance leases)	(32,442)	(40,883)
Long-term liabilities	(48)	(334)
Short-term borrowings	(243)	(2,293)
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Customer financing notes receivable	276	220
Short-term borrowings	(243)	(2,293)
Long-term debt (excluding finance leases)	(37,165)	(45,887)
Long-term liabilities	(46)	(320)
Fair Value Level 1 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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]
Customer financing notes receivable	276	220
Short-term borrowings	(160)	0
Long-term debt (excluding finance leases)	(28,842)	(45,802)
Long-term liabilities	(46)	(320)
Fair Value Level 3 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Customer financing notes receivable	0	0
Short-term borrowings	(83)	(2,293)
Long-term debt (excluding finance leases)	(8,323)	(85)
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		53
Marketable securities held in trusts	758	0
Derivative assets	49	46
Derivative liabilities	(381)	(282)
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		53
Marketable securities held in trusts	758
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
Marketable securities held in trusts	0
Derivative assets	49	46
Derivative liabilities	(381)	(282)
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
Marketable securities held in trusts	0
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0