Note 8 - Income Taxes - Deferred Tax Assets for Loss and Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2021 USD ($)
Net operating losses	$ 303
Tax credits	72
Balance as of December 31, 2021	375
Tax Years 2022 Through 2026 [Member]
Net operating losses	102
Tax credits	7
Balance as of December 31, 2021	109
Tax Years 2027 Through 2031 [Member]
Net operating losses	16
Tax credits	1
Balance as of December 31, 2021	17
Tax Years 2032 Through 2041 [Member]
Net operating losses	41
Tax credits	59
Balance as of December 31, 2021	100
Indefinite [Member]
Net operating losses	144
Tax credits	5
Balance as of December 31, 2021	$ 149