Financial Instruments - Cash Flow Hedges Effect on Accumulated Other Comprehensive Earnings/(Losses), Net of Tax (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Balance at beginning of period	$ 25,820	$ 25,835	$ 27,317	$ 25,602
Transfer of realized losses/(gains) in fair value to earnings	62	59	166	88
Balance at end of period	26,097	26,143	26,097	26,143
Cash flow hedges
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Transfer of realized losses/(gains) in fair value to earnings	7	12	88	12
Unrealized (loss)/gain in fair value	(6)	(74)	(29)	(139)
Derivative Cash Flow Hedges
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Balance at beginning of period	(155)	(233)	(213)	(168)
Balance at end of period	$ (154)	$ (295)	$ (154)	$ (295)