Note 5 - Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Provision for income taxes (Note 5)	$ (109)	$ (23)	$ (402)	$ (33)
Effective tax rate	22.70%	5.10%	22.10%	11.30%