Consolidated Statements of Beneficiaries' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Distributions declared per Common Share (USD per share)	$ 0.63	$ 0.60	$ 0.60
Cumulative Distributions [Member]
Distributions declared per Common Share (USD per share)	0.63	0.60	0.60
Noncontrolling Interest [Member]
Distributions declared per Common Share (USD per share)	$ 0.63	$ 0.60	$ 0.60