Note 11 - Non-Cash Investing and Financing Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Acquisition of real estate interests by assumption of mortgage debt		$ 20,800
Acquisition of real estate interests through proceeds held in escrow		31,738
Proceeds held in escrow through sale of real estate interests	$ 20,503	13,855
Issuance of common stock	91	486
Surrender of restricted common stock	(5,908)	(5,172)
Declaration of dividends paid in succeeding period	$ 116,631	111,357	$ 115,182
Increase in real estate and other assets		897,476
Increase in mortgages payable and other liabilities		$ 637,976