Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial Instruments and Fair Value [Line Items]
Fair value of debt securities with fair value option elected	$ 2,000
Gross realized gains on the sale of our marketable securities	899	$ 292	$ 1,300
Gross realized losses on the sale of our marketable securities	184	143	143
Other-than-temporary impairment losses		0	$ 0
Fair value of non-marketable equity securities	18,893	11,353
Equity method investments	1,400	$ 1,300
Foreign currency gain (loss) to be reclassified during next 12 months	124
Debt Securities
Financial Instruments and Fair Value [Line Items]
Net gain on debt securities with fair value option elected	$ 87
Cash flow hedges \| Foreign exchange contracts
Financial Instruments and Fair Value [Line Items]
Foreign exchange option contracts, maximum maturities	24 months
Valuation, Market Approach
Financial Instruments and Fair Value [Line Items]
Fair value of non-marketable equity securities	$ 9,700
Unrealized gain on equity securities	$ 1,500

Available-for-sale Debt Securities, Fair Value Option

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Financial Instruments and Fair Value [Line Items]

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of investment in equity security without readily determinable fair value.

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Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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