Capital Stock (Details) (USD $)	0 Months Ended			6 Months Ended				0 Months Ended
	May 29, 2012	Apr. 04, 2012	Jan. 10, 2012	Jun. 15, 2012	Jun. 17, 2011	Dec. 31, 2011	Jul. 09, 2012 Issuance of Equity [Member]	Jul. 11, 2012 Follow On Public Offering [Member]	Jul. 12, 2012 Private Placement [Member]
Capital Stock (Textuals) [Abstract]
Common stock, par value (in dollars per share)				$ 0.01		$ 0.01
Common stock, shares authorized				200,000,000		200,000,000	400,000,000
Stock Issued During Period, Shares, New Issues								20,000,000	7,211,538
Stock Issued During Period, Value, New Issues									$ 75,000,000
Proceeds from Issuance of Common Stock				$ 0	$ 149,674,000			$ 200,100,000
Lock up agreement period (in days)									150 days
Dividends Payable, Date to be Paid, Day, Month and Year	May 29, 2012	Apr. 04, 2012	Jan. 10, 2012
Dividends Payable, Date of Record, Day, Month and Year	May 15, 2012	Mar. 23, 2012	Dec. 30, 2011
Common stock, dividends, per share, declared (in dollars per share)	$ 0.08	$ 0.08	$ 0.08
Preferred stock, shares authorized				10,000,000		10,000,000
Preferred stock, par value (in dollars per share)				$ 0.01		$ 0.01
Preferred Stock, shares outstanding				0		0
Units of Partnership Interest, Amount				0		0
Operating Partnership Units Option To Redeem For Common Stock Ratio				1