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	35,617,000	0	0	35,219,000	0	398,000
Net unrealized change in fair value of interest rate swaps	(1,714,000)	0	0	0	(1,714,000)	0
Common dividends declared - $1.65 per share	(52,252,000)	0	0	(52,252,000)	0	0
Stock-based compensation, net of forfeitures	5,232,000	0	5,232,000	0	0	0
Issuance of 944,548 shares of common stock, common stock offering, net of expenses	59,110,000	0	59,110,000	0	0	0
Issuance of 2,647 shares of common stock, dividend reinvestment plan	165,000	0	165,000	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	(565,000)	0	0	0	0	(565,000)
BALANCE at Sep. 30, 2014	$ 562,454,000	$ 3,000	$ 853,198,000	$ (295,202,000)	$ (85,000)	$ 4,540,000