Income per Common Share of the Trust - Options Exercised (Details) - shares	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Stock Option [Member] | Common shares [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	12,000	65,000	44,000