Note 11 - Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Certificates of Deposit [Member]
Debt Securities, Cost	$ 26	$ 21
Debt Securities, Unrealized Gain	0	0
Debt Securities, Fair Value	26	21
Common Stock [Member]
Equity Securities, Cost	16	16
Equity Securities, Unrealized Gain	16	33
Available-for-sale securities	$ 32	$ 49

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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Amortized cost of 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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