Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Changes in accumulated other comprehensive income (loss), net of income taxes
Beginning of the period			$ 32,784
Net current period comprehensive income (loss)	$ 219	$ 306	(120)	$ (615)
End of the period	33,800		33,800
Cumulative Foreign Currency Translation Adjustments
Changes in accumulated other comprehensive income (loss), net of income taxes
Beginning of the period	(5,395)	(6,068)	(4,859)	(4,924)
Other comprehensive income (loss) before reclassifications	165	355	(371)	(789)
Net current period comprehensive income (loss)	165	355	(371)	(789)
End of the period	(5,230)	(5,713)	(5,230)	(5,713)
Net Actuarial (Losses) and Prior Service (Costs) and Credits
Changes in accumulated other comprehensive income (loss), net of income taxes
Beginning of the period	(3,786)	(3,483)	(3,871)	(3,540)
Other comprehensive income (loss) before reclassifications	(12)	(9)	10	(2)
Amounts reclassified from accumulated other comprehensive income	60	46	123	96
Net current period comprehensive income (loss)	48	37	133	94
End of the period	(3,738)	(3,446)	(3,738)	(3,446)
Cumulative Gains (Losses) on Derivative Instruments Designated as Cash Flow Hedges
Changes in accumulated other comprehensive income (loss), net of income taxes
Beginning of the period	(104)	165	(216)	(1)
Other comprehensive income (loss) before reclassifications	(28)	(67)	68	109
Amounts reclassified from accumulated other comprehensive income	34	(19)	50	(29)
Net current period comprehensive income (loss)	6	(86)	118	80
End of the period	$ (98)	$ 79	$ (98)	$ 79