Description of Business and Basis of Presentation (Recently Issued Accounting Standards) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 116,628	$ 119,035	$ 233,830	$ 238,915
Net cash provided by operating activities			(104,716)	(92,644)
Net cash used in investing activities			(134,376)	74,013
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				33,600
Net cash used in investing activities				33,600
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				(7,500)
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
Rental Property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	113,698	114,007	227,046	226,524
Fee and Other Revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 2,900	$ 5,000	$ 6,800	$ 12,400