Consolidated Statement of Changes in Equity - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands		Total		ATM Program [Member]	Common Shares [Member]	Common Shares [Member] ATM Program [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] ATM Program [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Shareholders' Equity [Member]	Total Shareholders' Equity [Member] ATM Program [Member]	Noncontrolling Interests [Member]	General Partners' Interest in Consolidated Partnership [Member] Noncontrolling Interests [Member]
Beginning Balance, at Dec. 31, 2016		$ 267,643	[1]		$ 29		$ 396,494		$ (141,695)	$ 859	$ 255,687		$ 11,941	$ 15
Beginning Balance (in shares), at Dec. 31, 2016		29,468,563			29,468,000
Beginning Balance (in units), at Dec. 31, 2016													1,103,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of noncontrolling interest OP units for common shares (in shares)					19,000								19,000
Exchange of noncontrolling interest OP units for common shares		$ 0					206				206		$ (206)
Issuance of shares under dividend reinvestment plan (in shares)					5,000
Issuance of common shares, net of offering costs		99,895		$ 7,724	$ 8	$ 1	99,887	$ 7,723			99,895	$ 7,724
Issuance of common shares, net of offering costs (in shares)					8,019,000	567,000
Issuance of shares under dividend reinvestment plan		63					63				63
Repurchase of common shares (in shares)	[2]				(154,000)
Repurchase of common shares	[2]	(1,987)					(1,987)				(1,987)
Share-based compensation (in shares)					602,000
Share-based compensation		4,833					4,833				4,833
Distributions		(22,027)							(21,140)		(21,140)		(621)	(266)
Unrealized gain on change in fair value of available-for-sale marketable securities		33								32	32		1
Unrealized loss on change in value of cash flow hedge		(48)								(46)	(46)		(2)
Reallocation of ownership percentage between parent and subsidiary		0					8			0	8		(8)
Net income		3,701							3,422		3,422		114	165
Ending Balance, at Jun. 30, 2017		$ 359,830	[1]		$ 38		$ 507,227		$ (159,413)	$ 845	$ 348,697		$ 11,219	$ (86)
Ending Balance (in shares), at Jun. 30, 2017		38,526,489			38,526,000
Ending Balance (in units), at Jun. 30, 2017													1,084,000

[1] Liabilities of consolidated Variable Interest Entities included in the total liabilities

[2] During the six months ended June 30, 2017, the Company acquired common shares held by employees who tendered owned common shares to satisfy the tax withholding on the lapse of certain restrictions on restricted common shares.