Note 23 - Supplemental Financial Information (Details) - Quarterly Results of Operations - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Results of Operations [Abstract]
Revenues from rental properties	$ 296,501	$ 283,387	$ 289,080	$ 275,506	$ 255,749	[1]	$ 246,555	[1]	$ 237,432	[1]	$ 219,152	[1]	$ 1,144,474	$ 958,888	$ 825,210
Net income attributable to the Company	$ 379,201	$ 77,572	$ 127,000	$ 310,342	$ 52,781		$ 194,708		$ 89,512		$ 87,000		$ 894,115	$ 424,001	$ 236,281
Net income per common share:
Basic	$ 0.87	$ 0.15	$ 0.27	$ 0.72	$ 0.09		$ 0.44		$ 0.18		$ 0.18		$ 2.01	$ 0.89	$ 0.43
Diluted	$ 0.87	$ 0.15	$ 0.27	$ 0.71	$ 0.09		$ 0.44		$ 0.18		$ 0.18		$ 2.00	$ 0.89	$ 0.43

[1] All periods have been adjusted to reflect the impact of operating properties sold during 2014, which are reflected in the caption Discontinued operations on the accompanying Consolidated Statements of Income. Upon the adoption of ASU 2014-08 on January 1, 2015, individual property dispositions will no longer qualify as a discontinued operation under the new guidance.