Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ (6,113)	$ (6,597)		$ (6,574)
Research and development expenditures	430	424	$ 406
Advertising costs	353	345	320
Maximum cash investments with single counterparty	170
Capital lease obligations	36	6	5
Accrued capital expenditures remaining unpaid	243	266	265
Payments for capital expenditures accrued and unpaid in prior year	266	265	264
Restricted net assets	711
Depreciation expense for property, plant and equipment	$ 793	$ 776	$ 779
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payment term	30 days
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payment term	90 days
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings				$ 23