Note 8 - Other Real Estate Investments - Preferred Equity Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues, net	$ 269,441	$ 259,792	$ 238,916	$ 289,744	$ 296,130	$ 282,871	$ 284,873	$ 295,010	$ 1,057,893	$ 1,158,884	$ 1,164,762
Operating expenses									(731,765)	(760,515)	(812,196)
Depreciation and amortization									(288,955)	(277,879)	(310,380)
Interest expense									(186,904)	(177,395)	(183,339)
Other expense, net									4,119	10,985	16,528
Net income									1,002,877	413,561	498,463
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Preferred Equity Investments [Member]
Revenues, net									44,600	66,600	77,000
Operating expenses									(11,100)	(16,000)	(15,500)
Depreciation and amortization									(2,900)	(3,200)	(4,300)
Gain on sale of properties									200	13,600	1,900
Interest expense									(7,000)	(11,900)	(16,900)
Other expense, net									(4,000)	(7,900)	(8,200)
Net income									$ 19,800	$ 41,200	$ 34,000