Note 7 - Goodwill and Other Acquired Intangible Assets, Net - Impairment Analysis (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill	$ 4,828	$ 0	$ 0	$ 0	$ 0	$ 4,828	$ 0
Finite-Lived Intangible Assets, Net					13,241
Goodwill [Line Items]
Impairment of goodwill	4,828	$ 0	$ 0	$ 0	0	4,828	$ 0
Client relationships
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived					1,000
Technology
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived					300
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived					0
Real Estate Segment
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill					0	4,828
Impairment of Intangible Assets, Finite-lived						13,700
Finite-Lived Intangible Assets, Net	18,385				13,241	18,385
Goodwill [Line Items]
Impairment of goodwill					0	4,828
Real Estate Segment | Client relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	16,281				11,991	16,281
Real Estate Segment | Technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 1,646				915	$ 1,646
Held-for-sale | Real Estate Segment
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net					$ 3,700