CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - Unaudited (USD $)	Total	Common Stock	Additional Paid-in Capital	Distributions In Excess Of Earnings	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interest in Joint Ventures
BALANCE at Dec. 31, 2012	$ 491,176,000	$ 3,000	$ 731,950,000	$ (245,249,000)	$ (392,000)	$ 4,864,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,308,000	0	0	7,154,000	0	154,000
Net unrealized change in fair value of interest rate swap	222,000	0	0	0	222,000	0
Common dividends declared - $.53 per share	(16,227,000)	0	0	(16,227,000)	0	0
Stock-based compensation, net of forfeitures	1,831,000	0	(1,831,000)	0	0	0
Issuance of 245,010 shares of common stock, common stock offering, net of expenses	13,798,000	0	13,798,000	0	0	0
Issuance of 933 shares of common stock, dividend reinvestment plan	54,000	0	54,000	0	0	0
Withheld 9,412 shares of common stock to satisfy tax withholding obligations in connection with the vesting of restricted stock	(528,000)	0	(528,000)	0	0	0
Distributions to noncontrolling interest	(195,000)	0	0	0	0	(195,000)
BALANCE at Mar. 31, 2013	$ 497,439,000	$ 3,000	$ 747,105,000	$ (254,322,000)	$ (170,000)	$ 4,823,000