CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - Unaudited (USD $)	Total	Common Stock	Additional Paid-in Capital	Distributions In Excess Of Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest in Joint Ventures
BALANCE at Dec. 31, 2013	$ 518,705,000	$ 3,000	$ 790,535,000	$ (278,169,000)	$ 1,629,000	$ 4,707,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,756,000	0	0	17,490,000	0	266,000
Net unrealized change in fair value of interest rate swaps	(2,777,000)	0	0	0	(2,777,000)	0
Common dividends declared - $1.08 per share	(34,062,000)	0	0	(34,062,000)	0	0
Stock-based compensation, net of forfeitures	(3,908,000)	0	(3,908,000)	0	0	0
Issuance of 634,138 shares of common stock, common stock offering, net of expenses	39,359,000	0	39,359,000	0	0	0
Issuance of 1,630 shares of common stock, dividend reinvestment plan	103,000	0	103,000	0	0	0
Withheld 31,417 shares of common stock to satisfy tax withholding obligations in connection with the vesting of restricted stock	(1,844,000)	0	(1,844,000)	0	0	0
Distributions to noncontrolling interest	(377,000)	0	0	0	0	(377,000)
BALANCE at Jun. 30, 2014	$ 540,771,000	$ 3,000	$ 832,061,000	$ (294,741,000)	$ (1,148,000)	$ 4,596,000