Recent Accounting Pronouncements and Updated Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative expenses	$ 1,369		$ 1,410	[1]	$ 4,061	$ 4,055	[1]
Other (income) expense, net	$ 26		16	[1]	$ 114	150	[1]
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax reform, reclassification from AOCI to retained earnings, tax effect		$ 163
Reclassifying Adjustment | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative expenses			19			69
Other (income) expense, net			$ 11			$ 13

[1] Prior year amounts have been reclassified to conform to the current year presentation as a result of the adoption of Accounting Standards Update (“ASU”) No. 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” For further information regarding the impact of the reclassification, see Note 1, Basis of Presentation, Note 3, Recent Accounting Pronouncements and Updated Accounting Policies and Note 13, Segment Information to the Condensed Consolidated Financial Statements.