CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Total stockholders' equity USD ($)	Shares of preferred stock	Shares of common stock	Preferred stock and paid in capital USD ($)	Common stock and paid in capital USD ($)	Distributions in excess of net income USD ($)	Noncontrolling interests USD ($)
Balance at Dec. 31, 2010	$ 1,846,965	$ 1,846,965			$ 337,790	$ 2,066,287	$ (557,112)
Balance (in shares) at Dec. 31, 2010			13,900,000	118,058,988
Increase (Decrease) in Stockholders' Equity
Net income	157,032	157,032					157,032
Distributions paid and payable	(245,904)	(245,904)					(245,904)
Shares issued in stock offerings, net of offering costs of $55,359, $13,773 and $25,200 for the year ended December 31, 2013, 2012 and 2011, respectively.	489,236	489,236				489,236
Shares issued in stock offerings, net of offering costs (in shares)				14,925,000
Shares issued pursuant to dividend reinvestment and stock purchase plan, net	1,930	1,930				1,930
Shares issued pursuant to dividend reinvestment and stock purchase plan, net (in shares)				59,605
Share-based compensation	5,595	5,595				5,595
Share-based compensation (in shares)				179,745
Balance at Dec. 31, 2011	2,254,854	2,254,854			337,790	2,563,048	(645,984)
Balance (in shares) at Dec. 31, 2011			13,900,000	133,223,338
Increase (Decrease) in Stockholders' Equity
Net income	159,152	159,152					159,152
Distributions paid and payable	(278,133)	(278,133)					(278,133)
Shares issued in stock offerings, net of offering costs of $55,359, $13,773 and $25,200 for the year ended December 31, 2013, 2012 and 2011, respectively.	395,377	395,377			395,377
Shares issued in stock offerings, net of offering costs (in shares)			16,350,000
Shares issued pursuant to dividend reinvestment and stock purchase plan, net	2,051	2,051				2,051
Shares issued pursuant to dividend reinvestment and stock purchase plan, net (in shares)				55,598
Preferred shares redeemed	(127,500)	(127,500)			(123,804)		(3,696)
Preferred shares redeemed (in shares)			(5,100,000)
Share-based compensation	6,993	6,993				6,993
Share-based compensation (in shares)				173,475
Balance at Dec. 31, 2012	2,412,794	2,412,794			609,363	2,572,092	(768,661)
Balance (in shares) at Dec. 31, 2012			25,150,000	133,452,411
Increase (Decrease) in Stockholders' Equity
Net income	246,283	245,564					245,564	719
Distributions paid and payable	(470,068)	(468,697)					(468,697)	(1,371)
Shares issued in stock offerings, net of offering costs of $55,359, $13,773 and $25,200 for the year ended December 31, 2013, 2012 and 2011, respectively.	1,133,574	1,133,574				1,133,574
Shares issued in stock offerings, net of offering costs (in shares)				27,025,000
Shares issued in conjunction with acquisition of ARCT, net of our shares owned by ARCT	1,997,850	1,997,850				1,997,850
Shares issued in conjunction with acquisition of ARCT, net of our shares owned by ARCT (in shares)				45,364,435
Issuance of preferred and common units	36,563							36,563
Shares issued pursuant to dividend reinvestment and stock purchase plan, net	55,244	55,244				55,244
Shares issued pursuant to dividend reinvestment and stock purchase plan, net (in shares)				1,449,139
Share-based compensation	9,118	9,118				9,118
Share-based compensation (in shares)				194,088
Balance at Dec. 31, 2013	$ 5,421,358	$ 5,385,447			$ 609,363	$ 5,767,878	$ (991,794)	$ 35,911
Balance (in shares) at Dec. 31, 2013			25,150,000	207,485,073