Note 11 - Retirement Plans - Summary of Funded Status and Amounts Recognized on Balance Sheets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Projected benefit obligation at beginning of year	$ 117	$ 126
Interest cost	5	5	$ 5
Actuarial loss (gain)	17	(11)
Benefits paid	(4)	(3)
Projected benefit obligation at end of year	135	117	126
Fair value of pension plan assets at beginning of year	84	88
Actual return on plan assets	14	(4)
Company contributions	3	3
Benefits paid	(4)	(3)
Fair value of pension plan assets at end of year	97	84	$ 88
Funded status of pension plan	(38)	(33)
Accrued benefit cost	5	2
Accumulated other comprehensive loss	(43)	(35)
Net liability recognized	$ (38)	$ (33)