Note 5 - Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Provision for income taxes (Note 5)	$ (67)	$ (22)	$ (293)	$ (10)
Effective tax rate	13.00%	(44.90%)	21.80%	(6.40%)