Note 15 - Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit (Credit) Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Settlement	$ 22	$ 0	$ 0
Pension Plan [Member]
Service cost	1,114	1,183	3,950
Interest cost	14,230	20,176	25,101
Expected return on plan assets	(42,168)	(41,821)	(40,457)
Amortization of prior service credits	0	0	(367)
Recognized net actuarial loss	5,469	6,922	5,958
Pension Settlement	22	0	0
Net periodic benefit (credit) cost	(21,333)	(13,540)	(5,815)
Other Postretirement Benefits Plan [Member]
Service cost	0	0	0
Interest cost	7,274	12,795	18,320
Expected return on plan assets	0	0	0
Amortization of prior service credits	(2,405)	(2,405)	(2,405)
Recognized net actuarial loss	6,516	9,277	9,262
Pension Settlement	0	0	0
Net periodic benefit (credit) cost	$ 11,385	$ 19,667	$ 25,177