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Summary of Significant Accounting Policies (Summary of Interest Capitalized and Depreciation Expense) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accounting Policies [Abstract]      
Depreciation expense $ 11,252 $ 10,666 $ 10,249