Financial Instruments - Cash Flow Hedges Effect on Accumulated Other Comprehensive Earnings/(Losses), Net of Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Balance at beginning of period	$ 25,713	$ 26,074	$ 25,195
Transfer of realized (gains)/losses in fair value to earnings	279	169	174
Balance at end of period	27,351	25,713	26,074
Cash Flow Hedges
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Transfer of realized (gains)/losses in fair value to earnings	154	(9)	27
Unrealized gain/(loss) in fair value	(199)	(45)	(19)
Derivative Cash Flow Hedges
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Balance at beginning of period	(167)	(113)	(121)
Balance at end of period	$ (212)	$ (167)	$ (113)