Note 8 - Other Real Estate Investments - Preferred Equity Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues	$ 296,130	$ 282,871	$ 284,873	$ 295,010	$ 284,201	$ 283,080	$ 293,403	$ 304,078	$ 1,158,884	$ 1,164,762	$ 1,200,834
Operating expenses									(760,515)	(812,196)	(863,355)
Depreciation and amortization									(277,879)	(310,380)	(360,811)
Interest expense									(177,395)	(183,339)	(191,956)
Other expense, net									11,814	13,041	2,559
Net income									413,561	498,463	439,671
Preferred Equity Investments [Member]
Revenues									66,600	77,000	75,400
Operating expenses									(16,000)	(15,500)	(14,700)
Depreciation and amortization									(3,200)	(4,300)	(4,600)
Gain on sale of operating properties									13,600	1,900	4,300
Interest expense									(11,900)	(16,900)	(20,400)
Other expense, net									(7,900)	(8,200)	(5,900)
Net income									$ 41,200	$ 34,000	$ 34,100