Condensed Consolidated Statement of Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock	Capital in Excess of Par Value	Accumulated Distributions in Excess of Earnings	Accumulated Other Comprehensive Loss	Total Stockholders' Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2010	$ 1,997,152	$ 2,481	$ 2,164,528	$ (163,040)	$ (7,188)	$ 1,996,781	$ 371
Beginning balance, shares at Dec. 31, 2010	248,070,364	248,070,364
Issuance of common stock, shares		94,108,456
Issuance of common stock	935,763	940	934,823			935,763
Distributions to noncontrolling interests	(34)						(34)
Distributions to investors	(141,992)			(141,992)		(141,992)
Commissions on stock sales and related dealer manager fees	(76,137)		(76,137)			(76,137)
Other offering costs	(12,879)		(12,879)			(12,879)
Redemptions of common stock, shares		(3,293,997)
Redemptions of common stock	(31,888)	(33)	(31,855)			(31,888)
Redeemable common stock	(46,450)		(46,450)			(46,450)
Purchase of investment from noncontrolling interest	(707)		(707)			(707)
Comprehensive income:
Allocation of net income	26,321			26,011		26,011	310
Unrealized loss on marketable securities	(1,082)				(1,082)	(1,082)
Unrealized loss on interest rate swaps	(19,385)				(19,385)	(19,385)
Total comprehensive income	5,854					5,544	310
Ending balance at Sep. 30, 2011	$ 2,628,682	$ 3,388	$ 2,931,323	$ (279,021)	$ (27,655)	$ 2,628,035	$ 647
Ending balance, shares at Sep. 30, 2011	338,884,823	338,884,823