Condensed Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Earnings including noncontrolling interests	$ 64,731,000	$ 59,143,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Performance incentive plan expense	5,057,000	4,297,000
Stock option expense - tax effect		122,000
Depreciation and amortization	42,802,000	36,227,000
Impairment - real estate	431,000
Impairment - commercial mortgage residual interests valuation	396,000	3,848,000
Amortization of notes payable discount	5,032,000	4,734,000
Amortization of deferred interest rate hedges	(47,000)	(124,000)
Equity in earnings of unconsolidated affiliate	(321,000)	(320,000)
Distributions received from unconsolidated affiliate	432,000	442,000
Gain on disposition of real estate, Investment Portfolio	(38,000)	(1,013,000)
Gain on disposition of real estate, Inventory Portfolio	(102,000)	(941,000)
Income tax valuation allowance		265,000
Other	266,000	(67,000)
Change in operating assets and liabilities, net of assets acquired and liabilities assumed in business combinations:
Additions to real estate, Inventory Portfolio	(790,000)	(397,000)
Proceeds from disposition of real estate, Inventory Portfolio	1,058,000	42,817,000
Decrease in real estate leased to others using the direct financing method	1,191,000	1,144,000
Increase in work in process	(856,000)	(499,000)
Decrease (increase) in mortgages, notes and accrued interest receivable	170,000	(264,000)
Decrease in receivables	1,734,000	925,000
Decrease (increase) in commercial mortgage residual interests	(204,000)	1,812,000
Decrease (increase) accrued rental income	93,000	(211,000)
Decrease in other assets	571,000	452,000
Increase in accrued interest payable	15,029,000	10,929,000
Increase (decrease) in other liabilities	1,548,000	(1,610,000)
Increase in tax liability	962,000	180,000
Net cash provided by operating activities	139,145,000	161,891,000
Cash flows from investing activities:
Proceeds from the disposition of real estate, Investment Portfolio	8,138,000	7,103,000
Additions to real estate, Investment Portfolio:
Accounted for using the operating method	(434,532,000)	(106,525,000)
Accounted for using the direct financing method	(1,747,000)
Increase in mortgages and notes receivable	(5,706,000)	(8,502,000)
Principal payments on mortgages and notes	4,938,000	14,026,000
Payment of lease costs	(862,000)	(965,000)
Acquired additional interest in controlled subsidiary		(1,603,000)
Other	(2,191,000)	(2,087,000)
Net cash used in investing activities	(431,962,000)	(98,553,000)
Cash flows from financing activities:
Proceeds from line of credit payable	504,800,000	38,100,000
Repayment of line of credit payable	(665,800,000)	(1,000,000)
Payment of interest rate hedge	(5,300,000)
Payment of debt costs	(5,464,000)
Repayment of mortgages payable	(816,000)	(6,190,000)
Proceeds from notes payable	295,731,000
Repayment of notes payable		(20,000,000)
Proceeds from issuance of common stock	299,528,000	14,220,000
Payment of Series C preferred stock dividends	(5,089,000)	(5,089,000)
Payment of common stock dividends	(96,915,000)	(93,762,000)
Noncontrolling interest contributions	41,000	28,000
Noncontrolling interest distributions	(45,000)	(861,000)
Stock issuance costs	(10,224,000)
Net cash provided by (used in) financing activities	310,447,000	(74,554,000)
Net increase (decrease) in cash and cash equivalents	17,630,000	(11,216,000)
Cash and cash equivalents at beginning of period	2,048,000	15,225,000
Cash and cash equivalents at end of period	19,678,000	4,009,000
Supplemental disclosure of cash flow information:
Interest paid, net of amount capitalized	37,117,000	35,616,000
Taxes paid (received)	(541,000)	430,000
Supplemental disclosure of non-cash investing and financing activities:
Issued 141,351 and 392,474 shares of restricted and unrestricted common stock in 2011 and 2010, respectively, pursuant to NNN's performance incentive plan	3,456,000	7,490,000
Issued 6,975 and 7,912 shares of common stock in 2011 and 2010, respectively, to directors pursuant to NNN's performance incentive plan	177,000	177,000
Issued 19,962 and 18,605 shares of common stock in 2011 and 2010, respectively, pursuant to NNN's Deferred Director Fee Plan	338,000	279,000
Surrender of 5,215 shares of restricted stock in 2011	109,000
Change in lease classification (direct financing lease to operating lease)	3,407,000
Change in other comprehensive income	(4,701,000)	687,000
Mortgage receivable accepted in connection with real estate transactions		5,950,000
Mortgages payable assumed in connection with real estate transactions		5,432,000
Real estate acquired in connection with mortgage receivable foreclosure		$ 4,350,000