Real Estate - Investment Portfolio (Summary Of Real Estate Subject To Operating Leases) (Details) (USD $) In Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Real estate subject to operating leases, gross	$ 2,824,877	$ 2,716,285
Less accumulated depreciation and amortization	(246,348)	(222,921)
Real estate subject to operating leases before work in process	2,578,529	2,493,364
Real estate subject to operating leases, net	2,603,827	2,519,950
Land And Improvements [Member]
Real estate subject to operating leases, gross	1,159,787	1,122,243
Buildings And Improvements [Member]
Buildings and improvements	1,663,800	1,592,752
Leasehold Interests [Member]
Leasehold interests	1,290	1,290
Work In Process [Member]
Work in process	$ 25,298	$ 26,586

Aggregate carrying amounts as of the balance sheet date of investments in leasehold interests

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- Definition

Real Estate Subject To Operating Leases Before Work In Process

+ Details

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Namespace Prefix:	nnn
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The current amount of expenditures for a real estate project that has not yet been completed.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of real estate held for productive use. This excludes land held for sale.

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of accumulated depreciation, by major property class, recorded on property subject to or available for lease as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 13
-Paragraph 23
-Subparagraph b(i)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 13
-Paragraph 19
-Subparagraph a

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The net book value of real estate property held for investment purposes.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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