Annual report pursuant to Section 13 and 15(d)

Construction Contract and Other Service Revenues (Narrative 1) (Details)

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Construction Contract and Other Service Revenues (Narrative 1) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Construction contract revenue      
Disaggregation of Revenue [Line Items]      
Performance obligations satisfied or already satisfied $ 53 $ 349 $ 586