Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications			$ (3,483)	$ (1,105)
Amounts reclassified from accumulated OCI			(1,338)	(1,007)
Net other comprehensive income (loss)			(4,821)	(2,112)
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance			5,470	4,249
Net other comprehensive income (loss)	$ 520	$ (1,152)	(4,821)	(2,112)
Accumulated other comprehensive income, ending balance	649	2,137	649	2,137
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance			(3,056)	(3,084)
Other comprehensive income (loss) before reclassifications			(1,398)	(166)
Amounts reclassified from accumulated OCI			0	0
Net other comprehensive income (loss)			(1,398)	(166)
Accumulated other comprehensive income, ending balance	(4,454)	(3,250)	(4,454)	(3,250)
Net Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance			48	(2)
Other comprehensive income (loss) before reclassifications			81	67
Amounts reclassified from accumulated OCI			0	0
Net other comprehensive income (loss)			81	67
Accumulated other comprehensive income, ending balance	129	65	129	65
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance			(37)	818
Other comprehensive income (loss) before reclassifications			(2,166)	(1,006)
Amounts reclassified from accumulated OCI			44	24
Net other comprehensive income (loss)			(2,122)	(982)
Accumulated other comprehensive income, ending balance	(2,159)	(164)	(2,159)	(164)
Defined Benefit Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance			8,515	6,517
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated OCI			(1,382)	(1,031)
Net other comprehensive income (loss)			(1,382)	(1,031)
Accumulated other comprehensive income, ending balance	$ 7,133	$ 5,486	$ 7,133	$ 5,486