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Income per Common Share of the Trust Income per Common Share of the Trust - Anti-dilutive Options (Details) - shares
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Stock Option [Member]    
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive Options Excluded from Computation of Earnings Per Share 188,000 2,400,000