Note 15 - Pension and Other Postretirement Benefit Plans - Schedule of Changes in Benefit Obligation, Plan Assets and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair value of plan assets at beginning of period	$ 740,978
Fair value of plan assets at end of period	733,966	$ 740,978
Funded status:
Salary Retirement (Note 15)	38,947	0
Pension Plan [Member]
Benefit obligation at beginning of period	778,868	720,098
Service cost	1,114	1,183	$ 3,950
Interest cost	14,230	20,176	25,101
Actuarial (gain) loss	(25,073)	84,663
Plan settlement, benefit obligation	(719)	0
Benefits and other payments	(45,414)	(47,252)
Benefit obligation at end of period	723,006	778,868	720,098
Fair value of plan assets at beginning of period	740,978	668,481
Actual return on plan assets	36,867	118,403
Company contributions	2,254	1,346
Benefits and other payments	(45,414)	(47,252)
Plan settlement, plan asset	(719)	0
Fair value of plan assets at end of period	733,966	740,978	668,481
Funded status:
Salary Retirement (Note 15)	38,947	0
Current liabilities	(1,974)	(2,531)
Noncurrent liabilities	(26,013)	(35,359)
Net asset (obligation) recognized	10,960	(37,890)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	231,726	256,988
Prior service credit	0	0
Net amount recognized (before tax effect)	231,726	256,988
Other Postretirement Benefits Plan [Member]
Benefit obligation at beginning of period	413,710	464,329
Service cost	0	0	0
Interest cost	7,274	12,795	18,320
Actuarial (gain) loss	(42,836)	(38,455)
Plan settlement, benefit obligation	0	0
Benefits and other payments	(24,851)	(24,959)
Benefit obligation at end of period	353,297	413,710	464,329
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0	0
Company contributions	24,851	24,959
Benefits and other payments	(24,851)	(24,959)
Plan settlement, plan asset	0	0
Fair value of plan assets at end of period	0	0	$ 0
Funded status:
Salary Retirement (Note 15)	0	0
Current liabilities	(23,638)	(26,073)
Noncurrent liabilities	(329,659)	(387,637)
Net asset (obligation) recognized	(353,297)	(413,710)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	82,851	132,203
Prior service credit	(16,138)	(18,544)
Net amount recognized (before tax effect)	$ 66,713	$ 113,659