Supplemental Equity and Comprehensive Income Information - SE Rf (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (decrease) in equity
Balance at the beginning of the period	$ 11,622	$ 10,343
Net income	606	1,326
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	167	292
Defined benefit pension and postretirement plans adjustment	116	83
Cash flow hedging instruments unrealized gain (loss)	(61)	(76)
Total other comprehensive income (loss), net of tax	222	299
Dividends declared	(810)	(702)
Stock-based compensation	144	128
Reacquired stock	(972)	(678)
Issuances pursuant to stock option and benefit plans	227	324
Balance at the end of the period	11,039	11,040
Common Stock and Additional Paid-in Capital
Increase (decrease) in equity
Balance at the beginning of the period	5,361	5,070
Other comprehensive income (loss), net of tax:
Stock-based compensation	144	128
Balance at the end of the period	5,505	5,198
Retained Earnings
Increase (decrease) in equity
Balance at the beginning of the period	39,115	37,907
Net income	602	1,323
Other comprehensive income (loss), net of tax:
Dividends declared	(810)	(702)
Issuances pursuant to stock option and benefit plans	(454)	(434)
Balance at the end of the period	38,453	38,094
Treasury Stock
Increase (decrease) in equity
Balance at the beginning of the period	(25,887)	(25,434)
Other comprehensive income (loss), net of tax:
Reacquired stock	(972)	(678)
Issuances pursuant to stock option and benefit plans	681	758
Balance at the end of the period	(26,178)	(25,354)
Accumulated Other Comprehensive Income (Loss)
Increase (decrease) in equity
Balance at the beginning of the period	(7,026)	(7,245)
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	168	289
Defined benefit pension and postretirement plans adjustment	116	83
Cash flow hedging instruments unrealized gain (loss)	(61)	(76)
Balance at the end of the period	(6,803)	(6,949)
Noncontrolling Interest
Increase (decrease) in equity
Balance at the beginning of the period	59	45
Net income	4	3
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	(1)	3
Balance at the end of the period	$ 62	$ 51