Note 11 - Retirement Plans - Components of Net Periodic Benefit Cost for Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest cost	$ 4	$ 5	$ 5
Expected return on plan assets	(6)	(5)	(6)
Recognized net actuarial loss	1	0	0
Net periodic pension benefit	$ (1)	$ 0	$ (1)