Note 6 - Impairments (Details Textual) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Impairment Charges, Total		$ 48,743	$ 79,207	$ 67,331
Impairment of Real Estate		48,700	79,200
Equity Method Investments [Member]
Impairment of Real Estate		$ 5,600	$ 6,900	4,800
Properties Marketed for Sale [Member]
Asset Impairment Charges, Total	$ 41,000
Impaired Due to Unfavorable Local Market Conditions [Member]
Asset Impairment Charges, Total				$ 16,200

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration