Fair Value Measurements (Narrative) (Details) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Fair Value Measurements [Line Items]
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 1,700	$ 900
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 1,800	$ 7
Assets [Member] \| Weighted Average [Member] \| Fair Value, Recurring [Member] \| Inventories Component [Member]
Fair Value Measurements [Line Items]
Basis	4.30%	28.20%
Liabilities [Member] \| Weighted Average [Member] \| Fair Value, Recurring [Member] \| Inventories Component [Member]
Fair Value Measurements [Line Items]
Basis	13.70%	14.70%

Adjustment to current market value, based on location, that a market participant is willing to pay, used as an input to measure fair value.

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Fair Value Measurements [Line Items]

+ References

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Amount of unrealized gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3) and still held.

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