Equity Activity - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			$ 18,392	$ 14,424
Other comprehensive income/(loss)			1,877	1,442
Balance at the End of the Period	$ 19,757	$ 17,159	19,757	17,159
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			(29,398)	(29,607)
Other comprehensive income before reclassifications			721	117
Amount reclassified from accumulated other comprehensive income			1,155	1,326
Other comprehensive income/(loss)	669	440	1,877	1,442
Balance at the End of the Period	(27,521)	(28,164)	(27,521)	(28,164)
Net Unrealized Gains/(Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			319	100
Other comprehensive income before reclassifications	(50)	21	(146)	(139)
Amount reclassified from accumulated other comprehensive income			(219)	12
Other comprehensive income/(loss)	(94)	29	(365)	(127)
Balance at the End of the Period	(46)	(28)	(46)	(28)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			(3,603)	(3,463)
Other comprehensive income before reclassifications			794	303
Amount reclassified from accumulated other comprehensive income			0	0
Other comprehensive income/(loss)	284	(49)	794	303
Balance at the End of the Period	(2,809)	(3,161)	(2,809)	(3,161)
Net Change Retirement-Related Benefit Plans
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			(26,116)	(26,248)
Other comprehensive income before reclassifications			72	(25)
Amount reclassified from accumulated other comprehensive income			1,374	1,292
Other comprehensive income/(loss)	479	461	1,446	1,267
Balance at the End of the Period	(24,670)	(24,981)	(24,670)	(24,981)
Net Unrealized Gains/(Losses) on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period			2	5
Other comprehensive income before reclassifications	0	(1)	1	(22)
Amount reclassified from accumulated other comprehensive income			0	22
Other comprehensive income/(loss)	(1)	(1)	2	0
Balance at the End of the Period	$ 4	$ 4	$ 4	$ 4