EQUITY (Details) (USD $)	9 Months Ended		0 Months Ended	9 Months Ended	0 Months Ended		9 Months Ended		0 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Mar. 20, 2013 Series C Cumulative Redeemable Preferred Stock	Sep. 30, 2013 Series C Cumulative Redeemable Preferred Stock	Sep. 19, 2013 Common Stock	Jan. 14, 2013 Common Stock	Sep. 30, 2013 Common Stock	Sep. 30, 2012 Common Stock	Mar. 01, 2013 Common Stock Executive officers	Jun. 13, 2013 Common Stock Director	Sep. 30, 2013 Common Stock Director
Equity
Shares of common stock issued to redeem common units							2,466,404	4,015,192
New issued stock (in shares)			3,400,000		17,250,000	17,250,000
Net proceeds, after the underwriting discount and offering-related expenses	$ 389,389,000	$ (707,000)	$ 81,700,000		$ 152,200,000	$ 148,000,000
Underwriting discount and offering-related expenses			$ 3,300,000		$ 6,500,000	$ 7,300,000
Stock issued to officers and directors (in shares)							325,758	208,027	292,090	29,228	4,440
Preferred stock, dividend rate (as a percent)			7.125%	7.125%
Preferred stock, liquidation preference (in dollars per share)				$ 25
Annual dividend rate per share (in dollars per share)				$ 1.78125