Description of Business and Basis of Presentation (Recently Issued Accounting Standards) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Rental property revenues	$ 113,348	$ 112,517
Fee and other revenue	3,900	7,400
Net cash provided by operating activities	20,906	25,233
Net cash used in investing activities	$ 82,813	78,271
Cumulative effect of change in accounting principle			$ 22,329
Distributions in Excess of Net Income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle			22,329
Accounting Standards Update 2016-15 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities		2,100
Net cash used in investing activities		2,100
Accounting Standards Update 2016-18 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities		$ 2,100
Accounting Standards Update 2017-05 | Distributions in Excess of Net Income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle			$ 22,300