Note 8 - Other Real Estate Investments and Other Assets - Preferred Equity Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 284,201	$ 283,080	$ 293,403	$ 304,078	$ 315,225	$ 294,845	$ 297,176	$ 293,588	$ 1,164,762	$ 1,200,834	$ 1,170,792
Operating expenses									(812,196)	(863,355)	(869,969)
Depreciation and amortization									(310,380)	(360,811)	(355,320)
Interest expense									(183,339)	(191,956)	(192,549)
Other expense, net									13,041	2,559	5,425
Net income									498,463	439,671	386,138
Preferred Equity Investments [Member]
Revenues									77,000	75,400	102,600
Operating expenses									(15,500)	(14,700)	(27,400)
Depreciation and amortization									(4,300)	(4,600)	(6,700)
Gain on sale of operating properties									1,900	4,300	5,300
Interest expense									(16,900)	(20,400)	(26,700)
Other expense, net									(8,200)	(5,900)	(11,500)
Net income									$ 34,000	$ 34,100	$ 35,600