Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2012	Dec. 31, 2011
ASSETS
Accounted for using the operating method, net of accumulated depreciation and amortization	$ 3,393,906,000	$ 3,223,304,000
Accounted for using the direct financing method	25,359,000	25,752,000
Real estate, held for sale	42,997,000	38,686,000
Investment in unconsolidated affiliate	4,312,000	4,358,000
Mortgages, notes and accrued interest receivable, net of allowance	36,366,000	33,428,000
Commercial mortgage residual interests	15,016,000	15,299,000
Cash and cash equivalents	3,033,000	2,082,000
Receivables, net of allowance of $1,843 and $1,403, respectively	1,563,000	2,149,000
Accrued rental income, net of allowance of $4,875 and $4,870, respectively	25,687,000	25,187,000
Debt costs, net of accumulated amortization of $16,159 and $15,332, respectively	9,975,000	10,802,000
Other assets	54,324,000	53,382,000
Total assets	3,612,538,000	3,434,429,000
LIABILITIES AND EQUITY
Line of credit payable	26,200,000	65,600,000
Mortgages payable	22,883,000	23,171,000
Notes payable - convertible, net of unamortized discount of $5,319 and $6,363, respectively	356,416,000	355,371,000
Notes payable, net of unamortized discount of $4,897 and $5,033, respectively	895,103,000	894,967,000
Accrued interest payable	21,885,000	15,108,000
Other liabilities	73,879,000	76,336,000
Total liabilities	1,396,366,000	1,430,553,000
Stockholders' equity:
Common stock, $0.01 par value. Authorized 190,000,000 shares; 106,595,333 and 104,754,859 shares issued and outstanding, respectively	1,067,000	1,049,000
Excess stock, $0.01 par value. Authorized 205,000,000 shares; none issued or outstanding	0	0
Capital in excess of par value	1,990,633,000	1,958,225,000
Retained earnings (loss)	(60,623,000)	(44,946,000)
Accumulated other comprehensive income (loss)	(3,775,000)	(3,830,000)
Total stockholders' equity of NNN	2,214,802,000	2,002,498,000
Noncontrolling interests	1,370,000	1,378,000
Total equity	2,216,172,000	2,003,876,000
Total liabilities and equity	3,612,538,000	3,434,429,000
Series D Depositary Share [Member]
Stockholders' equity:
Series D, 11,500,000 depositary shares issued and outstanding, at stated liquidation value of $25 per share	287,500,000	0
Series C, 3,680,000 depositary shares issued and outstanding, at stated liquidation value of $25 per share	287,500,000	0
Series C Depositary Share [Member]
Stockholders' equity:
Series D, 11,500,000 depositary shares issued and outstanding, at stated liquidation value of $25 per share	0	92,000,000
Series C, 3,680,000 depositary shares issued and outstanding, at stated liquidation value of $25 per share	$ 0	$ 92,000,000