Note 6 - Stockholders' Equity - Schedule of Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Balance Begning	$ 1,968,104	$ 1,978,967
Balance Ending	1,958,630	1,992,157
Changes in fair value of derivative contracts designated as hedge transactions [Member]
Balance Begning	13,708	9,162
Changes in fair value of derivative contracts	(6,835)	8,665
Gains and deferred gains transferred from accumulated other comprehensive income	1,432	(2,149)
Balance Ending	8,305	15,678
Adjustments For Pension Plans [Member]
Balance Begning	(7,871)	(6,714)
Changes in fair value of derivative contracts	0	0
Gains and deferred gains transferred from accumulated other comprehensive income	0	0
Balance Ending	(7,871)	(6,714)
Accumulated Distributions in Excess of Net Income [Member]
Balance Begning	5,837	2,448
Changes in fair value of derivative contracts	(6,835)	8,665
Gains and deferred gains transferred from accumulated other comprehensive income	1,432	(2,149)
Balance Ending	$ 434	$ 8,964