Equity Activity - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	$ 20,727	$ 20,985
Other comprehensive income/(loss)	1,080	(686)
Balance at the End of the Period	21,513	20,128
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	(29,337)	(28,597)
Other comprehensive income before reclassifications	475	(1,174)
Amount reclassified from accumulated other comprehensive income	606	488
Other comprehensive income/(loss)	1,080	(686)
Balance at the End of the Period	(28,257)	(29,283)
Net Unrealized Gains/(Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	(456)	(179)
Other comprehensive income before reclassifications	140	(135)
Amount reclassified from accumulated other comprehensive income	119	68
Other comprehensive income/(loss)	259	(67)
Balance at the End of the Period	(197)	(246)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	(4,665)	(3,700)
Other comprehensive income before reclassifications	321	(1,041)
Other comprehensive income/(loss)	321	(1,041)
Balance at the End of the Period	(4,343)	(4,741)
Net Change Retirement-Related Benefit Plans
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	(24,216)	(24,718)
Other comprehensive income before reclassifications	14	3
Amount reclassified from accumulated other comprehensive income	486	419
Other comprehensive income/(loss)	500	422
Balance at the End of the Period	(23,716)	(24,296)
Net Unrealized Gains/(Losses) on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	0	0
Other comprehensive income before reclassifications	0	0
Other comprehensive income/(loss)	0	0
Balance at the End of the Period	$ (1)	$ 0