Note 12 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Fair Value, Recurring [Member]
Marketable equity securities		$ 10,665	$ 9,045
Marketable equity securities		10,665	9,045
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable equity securities		10,665	9,045
Marketable equity securities		10,665	9,045
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable equity securities		0	0
Marketable equity securities		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable equity securities			0
Marketable equity securities			0
Fair Value, Nonrecurring [Member]
Real estate		78,700	99,693
Investments in real estate joint ventures	[1]		62,429
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Real estate		0	0
Investments in real estate joint ventures	[1]		0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Real estate		0	0
Investments in real estate joint ventures	[1]		0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Real estate		$ 78,700	99,693
Investments in real estate joint ventures	[1]		$ 62,429

[1] Fair value measurement as of date of deconsolidation.