Equity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount		$ 400,000,000.0
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 163,500,000
Common Stock
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased (in shares)	510,498
Redemption of Operating Partnership units (in shares)	335,250
Limited Partners
Equity, Class of Treasury Stock [Line Items]
Direct and Indirect Ownership Interest in Operating Partnerships	558,750