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Financial Instruments - Information on Debt and Equity Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	$ 89	$ 1,768
Debt securities, gross unrealized gains	0	17
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	89	1,785
Publicly traded equity securities, fair value	1,787	838
Total debt and publicly traded equity securities, fair value	1,876	2,623
Unrealized net gains	163	160
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0	668
Debt securities, gross unrealized gains	0	0
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	0	668
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0	608
Debt securities, gross unrealized gains	0	13
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	0	621
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	84	266
Debt securities, gross unrealized gains	0	3
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	84	269
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0	226
Debt securities, gross unrealized gains	0	1
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	0	227
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	5	0
Debt securities, gross unrealized gains	0	0
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	5	0
Fair Value, Measurements, Recurring | Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	0	621
Fair Value, Measurements, Recurring | U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	0	209
Fair Value, Measurements, Recurring | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	0	227
Fair Value, Measurements, Recurring | Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	5	0
Fair Value, Measurements, Recurring | Publicly traded equity securities
Debt Securities, Available-for-sale [Line Items]
Publicly traded equity securities, fair value	$ 780	$ 518

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) 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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