Acquisitions and Dispositions (Divestitures, Major Classes of Assets and Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charges	$ 93	$ 0	$ 0
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charges	52
Cash and cash equivalents	20
Cash and cash equivalents	5
Inventories	5
Assets held for sale	30
Assets held for sale	14
Operating lease liabilities	6
Deferred income taxes	3
Other liabilities	1
Liabilities held for sale	$ 24