Note 12 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Fair Value, Recurring [Member]
Marketable equity securities		$ 10,705	$ 9,045
Marketable equity securities		10,705	9,045
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable equity securities		10,705	9,045
Marketable equity securities		10,705	9,045
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable equity securities
Marketable equity securities
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable equity securities
Marketable equity securities
Fair Value, Nonrecurring [Member]
Real estate		13,700	99,693
Investments in real estate joint ventures (1)	[1]		62,429
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Real estate
Investments in real estate joint ventures (1)	[1]
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Real estate
Investments in real estate joint ventures (1)	[1]
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Real estate		$ 13,700	99,693
Investments in real estate joint ventures (1)	[1]		$ 62,429

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