Supplemental Equity and Comprehensive Income Information - SE Rf (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (decrease) in equity
Balance at the beginning of the period	$ 9,848	$ 11,622
Net income	893	606
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	77	167
Defined benefit pension and postretirement plans adjustment	84	116
Cash flow hedging instruments	6	(61)
Total other comprehensive income (loss), net of tax	167	222
Dividends declared	(830)	(810)
Stock-based compensation	112	144
Reacquired stock	(666)	(972)
Issuances pursuant to stock option and benefit plans	219	227
Balance at the end of the period	9,757	11,039
ASU 2016-02 Leases
Increase (decrease) in equity
Impact of ASUs	14
Common Stock and Additional Paid-in Capital
Increase (decrease) in equity
Balance at the beginning of the period	5,652	5,361
Other comprehensive income (loss), net of tax:
Stock-based compensation	112	144
Balance at the end of the period	5,764	5,505
Retained Earnings
Increase (decrease) in equity
Balance at the beginning of the period	40,636	39,115
Net income	891	602
Other comprehensive income (loss), net of tax:
Dividends declared	(830)	(810)
Issuances pursuant to stock option and benefit plans	(405)	(454)
Balance at the end of the period	41,159	38,453
Retained Earnings | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
Increase (decrease) in equity
Impact of ASUs	853
Retained Earnings | ASU 2016-02 Leases
Increase (decrease) in equity
Impact of ASUs	14
Treasury Stock
Increase (decrease) in equity
Balance at the beginning of the period	(29,626)	(25,887)
Other comprehensive income (loss), net of tax:
Reacquired stock	(666)	(972)
Issuances pursuant to stock option and benefit plans	624	681
Balance at the end of the period	(29,668)	(26,178)
Accumulated Other Comprehensive Income (Loss)
Increase (decrease) in equity
Balance at the beginning of the period	(6,866)	(7,026)
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	77	168
Defined benefit pension and postretirement plans adjustment	84	116
Cash flow hedging instruments	6	(61)
Balance at the end of the period	(7,552)	(6,803)
Accumulated Other Comprehensive Income (Loss) | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
Increase (decrease) in equity
Impact of ASUs	(853)
Accumulated Other Comprehensive Income (Loss) | ASU 2016-02 Leases
Increase (decrease) in equity
Impact of ASUs	(853)
Noncontrolling Interest
Increase (decrease) in equity
Balance at the beginning of the period	52	59
Net income	2	4
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment		(1)
Balance at the end of the period	$ 54	$ 62