Note 10 - Fair Value Measurements - Estimate of Fair Value Differs from Carrying Amounts (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Reported Value Measurement [Member] | Marketable Securities [Member]
Marketable securities (1)	[1]	$ 8,141	$ 7,565
Reported Value Measurement [Member] | Mortgages [Member]
Mortgages payable (3)	[2]	1,213,120	1,614,982
Reported Value Measurement [Member]
Notes payable (2)	[3]	3,786,921	3,761,328
Estimate of Fair Value Measurement [Member] | Marketable Securities [Member]
Marketable securities (1)	[1]	8,141	7,564
Estimate of Fair Value Measurement [Member] | Mortgages [Member]
Mortgages payable (3)	[2]	1,229,655	1,629,760
Estimate of Fair Value Measurement [Member]
Notes payable (2)	[3]	3,922,026	$ 3,820,205
Mortgages [Member]
Mortgages payable (3)		$ 1,600

[1] As of September 30, 2016 and December 31, 2015, the Company determined that $6.5 million and $5.9 million, respectively, of the Marketable securities estimated fair value were classified within Level 1 of the fair value hierarchy and the remaining $1.6 million and $1.7 million, respectively, were classified within Level 3 of the fair value hierarchy.

[2] The Company determined that its valuation of Mortgages payable was classified within Level 3 of the fair value hierarchy.

[3] The Company determined that its valuation of Notes payable was classified within Level 2 of the fair value hierarchy.