Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Earnings including noncontrolling interests	$ 92,416,000	$ 73,353,000	$ 56,399,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Performance incentive plan expense	8,283,000	5,756,000	4,172,000
Stock option expense - tax effect	0	122,000	190,000
Depreciation and amortization	58,817,000	49,084,000	48,485,000
Impairment losses and other charges	2,115,000	7,458,000	41,710,000
Impairment - commercial mortgage residual interests valuation	1,024,000	3,995,000	498,000
Amortization of notes payable discount	6,191,000	6,360,000	6,006,000
Amortization of deferred interest rate hedges	9,000	(166,000)	(159,000)
Equity in earnings of unconsolidated affiliate	(474,000)	(428,000)	(421,000)
Distributions received from unconsolidated affiliate	593,000	578,000	607,000
Gain on disposition of real estate portfolio	(721,000)	(2,075,000)	(2,987,000)
Gain on extinguishment of debt	0	0	(3,432,000)
Deferred income taxes	884,000	(2,544,000)	(16,649,000)
Income tax valuation allowance	0	3,121,000	14,900,000
Change in operating assets and liabilities, net of assets acquired and liabilities assumed in business combinations:
Additions to held for sale real estate	(1,025,000)	(478,000)	(2,457,000)
Proceeds from disposition of held for sale real estate	1,993,000	42,817,000	6,276,000
Decrease in real estate leased to others using the direct financing method	1,595,000	1,544,000	1,378,000
Decrease (increase) in work in process	(1,213,000)	(755,000)	(786,000)
Increase in mortgages, notes and accrued interest receivable	(96,000)	(467,000)	(10,000)
Decrease (increase) in receivables	1,108,000	(219,000)	941,000
Decrease (increase) in commercial mortgage residual interests	(654,000)	1,516,000	(291,000)
Decrease (increase) in accrued rental income	253,000	124,000	(2,061,000)
Decrease (increase) in other assets	746,000	(53,000)	(172,000)
Decrease in accrued interest payable	7,766,000	(129,000)	(137,000)
Decrease in other liabilities	2,682,000	(431,000)	(2,930,000)
Increase (decrease) in current tax liability	654,000	(169,000)	432,000
Net cash provided by operating activities	182,946,000	187,914,000	149,502,000
Cash flows from investing activities:
Proceeds from the disposition of real estate, Investment Portfolio	10,696,000	10,312,000	14,588,000
Additions to real estate, Investment Portfolio:
Accounted for using the operating method	(756,633,000)	(230,928,000)	(44,433,000)
Payments To Acquire Real Estate Held For Investments Direct Financing Lease	(1,747,000)	0	0
Increase in mortgages and notes receivable	(9,838,000)	(8,564,000)	(959,000)
Principal payments on mortgages and notes receivable	6,837,000	13,818,000	4,009,000
Payment of lease costs	(1,589,000)	(1,324,000)	(451,000)
Other	206,000	(3,574,000)	(817,000)
Net cash used in investing activities	(752,068,000)	(220,260,000)	(28,063,000)
Cash flows from financing activities:
Proceeds from line of credit payable	805,300,000	278,900,000	132,400,000
Repayment of line of credit payable	(900,700,000)	(117,900,000)	(158,900,000)
Payment of interest rate hedge	(5,218,000)	0	0
Repayment of mortgages payable	(1,098,000)	(6,453,000)	(1,000,000)
Proceeds from notes payable	295,731,000	0	0
Repurchase of notes payable – convertible – debt component	0	0	(14,785,000)
Repurchase of notes payable – convertible – equity component	0	0	(795,000)
Repayment of notes payable	0	(20,000,000)	0
Payment of debt costs	(5,582,000)	(75,000)	(6,275,000)
Proceeds from issuance of common stock	540,560,000	17,692,000	68,060,000
Payment of Series C preferred stock dividends	(6,785,000)	(6,785,000)	(6,785,000)
Payment of common stock dividends	(133,720,000)	(125,391,000)	(120,256,000)
Noncontrolling interest distributions	(45,000)	(861,000)	(552,000)
Noncontrolling interest contributions	41,000	43,000	152,000
Stock issuance costs	(19,328,000)	(1,000)	(104,000)
Net cash provided by (used in) financing activities	569,156,000	19,169,000	(108,840,000)
Net increase (decrease) in cash and cash equivalents	34,000	(13,177,000)	12,599,000
Cash and cash equivalents at beginning of year	2,048,000	15,225,000	2,626,000
Cash and cash equivalents at end of year	2,082,000	2,048,000	15,225,000
Supplemental disclosure of cash flow information:
Interest paid, net of amount capitalized	63,474,000	62,386,000	61,475,000
Taxes paid (received)	(561,000)	472,000	(63,000)
Supplemental disclosure of non-cash investing and financing activities:
Issued 141,351, 392,474 and 262,546 shares of restricted and unrestricted common stock in 2011, 2010 and 2009, respectively, pursuant to NNN's performance incentive plan	3,456,000	6,889,000	4,290,000
Issued 9,632, 10,092 and 6,594 shares of common stock in 2011, 2010 and 2009, respectively, to directors pursuant to NNN's performance incentive plan	250,000	236,000	118,000
Issued 26,023, 25,066 and 41,604 shares of common stock in 2011, 2010 and 2009, respectively, pursuant to NNN's Deferred Director Fee Plan	449,000	401,000	611,000
Surrender of 5,215 shares of restricted stock in 2008	109,000	0	0
Change in other comprehensive income	(5,491,000)	1,150,000	(1,903,000)
Change in lease classification (direct financing lease to operating lease)	3,407,000	0	0
Transfer of real estate from Portfolio to held for sale	0	0	16,058,000
Note and mortgage receivable accepted in connection with real estate transactions	0	5,950,000	1,550,000
Mortgages payable assumed in connection with real estate transactions	0	5,432,000	0
Real estate acquired in connection with mortgage receivable foreclosure	0	6,250,000	4,240,000
Assets received in note receivable foreclosure	0	0	5,527,000
Note receivable foreclosures	$ 0	$ 0	$ (17,013,000)