Note 12 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Fair Value, Measurements, Nonrecurring [Member]
Real estate		$ 117,070	$ 108,313
Investments in real estate joint ventures	[1]	62,429
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Real estate
Investments in real estate joint ventures	[1]
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Real estate
Investments in real estate joint ventures	[1]
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Real estate		117,070	108,313
Investments in real estate joint ventures	[1]	62,429
Fair Value, Measurements, Recurring [Member]
Marketable equity securities		11,838	11,936
Interest rate swaps		72	344
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable equity securities		11,838	11,936
Interest rate swaps
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable equity securities
Interest rate swaps		72	344
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable equity securities
Interest rate swaps

[1] Fair value measurement as of date of deconsolidation. See Footnotes 3 and 5 to the Notes to the Company's Condensed Consolidated Financial Statements for further detail and discussion.