Note 6 - Stockholders' Equity - Schedule of Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024
Balance Beginning	$ 2,073,967	$ 2,039,514	$ 1,958,630	$ 1,968,104
Balance Ending	2,310,033	2,073,967	1,980,065	1,958,630
Changes in fair value of derivative contracts designated as hedge transactions
Balance Beginning	8,428	5,994	8,305	13,708
Changes in fair value of derivative contracts	5,748	2,787	(4,545)	(3,971)
Gains and deferred gains transferred from accumulated other comprehensive income	(2,495)	(353)	(1,943)	(1,432)
Balance Ending	11,681	8,428	1,817	8,305
Adjustments For Pension Plans
Balance Beginning	(16,260)	(16,260)	(7,871)	(7,871)
Changes in fair value of derivative contracts	0	0	0	0
Gains and deferred gains transferred from accumulated other comprehensive income	0	0	0	0
Balance Ending	(16,260)	(16,260)	(7,871)	(7,871)
Accumulated Distributions in Excess of Net Income
Balance Beginning	(7,832)	(10,266)	434	5,837
Changes in fair value of derivative contracts	5,748	2,787	(4,545)	(3,971)
Gains and deferred gains transferred from accumulated other comprehensive income	(2,495)	(353)	(1,943)	(1,432)
Balance Ending	$ (4,579)	$ (7,832)	$ (6,054)	$ 434