Note 7 - Investment and Advances in Real Estate Joint Ventures - Investment and Advances to Real Estate Joint Ventures - Income Statements (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	$ 201,234	$ (38,394)	$ 747,893	$ 90,100	$ 109,419	$ 83,990	$ 101,027	$ 116,169	1,000,833	410,605	497,795
Impairment charges									(6,624)	(48,743)	(79,207)
Net income									1,002,877	413,561	498,463
KIR [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Revenues, net									173,900	193,600	197,200
Operating expenses									(49,500)	(51,000)	(53,300)
Depreciation and amortization									(36,900)	(38,000)	(42,200)
Gain on sale of properties									0	32,200	13,500
Interest expense									(23,800)	(28,200)	(33,300)
Other expense, net									(1,600)	(1,100)	(1,500)
Net income									62,100	107,500	80,400
Excluding KIR [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Revenues, net									282,400	317,600	309,100
Operating expenses									(101,900)	(99,400)	(92,800)
Depreciation and amortization									(75,000)	(76,900)	(80,300)
Gain on sale of properties									200	15,000	46,800
Interest expense									(31,200)	(47,100)	(46,800)
Other expense, net									(10,800)	(14,200)	(2,900)
Impairment charges									(4,400)	(39,500)	(20,700)
Net income									$ 59,300	$ 55,500	$ 112,400