No authoritative reference available.

No definition available.

Name:	aei21_AverageLeaseTerm
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Data Type:	xbrli:normalizedStringItemType
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- Definition

Amount of acquired leases acquired as part of a real property acquisition at below market lease rate with a finite life.

+ References

No definition available.

+ Details

Name:	us-gaap_BelowMarketLeaseAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e845-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Acquisition Date

-URI http://asc.fasb.org/extlink&oid=6919109

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e848-128460

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Name of the acquired entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the amount of value allocated by a lessor (acquirer) to lease agreements which exist at acquisition of a leased property. Such amount may include the value assigned to existing tenant relationships and excludes the market adjustment component of the value assigned for above or below-market leases acquired.

+ References

No definition available.

+ Details

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

- Definition

The aggregate revenue from real estate operations during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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Balance Type:	credit
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- Details

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Real Estate Held for Investment (Details) (USD $)	0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended
Real Estate Held for Investment (Details) (USD $)	May 29, 2014	May 29, 2015	Jul. 03, 2014	Jul. 03, 2015
Tractor Supply Canton GA \| Leases, Acquired-in-Place [Member]
Real Estate Held for Investment (Details) [Line Items]
Finite-Lived Intangible Asset, Acquired-in-Place Leases	$ 185,920
Tractor Supply Canton GA \| Off Market Unfavorable Lease Member
Real Estate Held for Investment (Details) [Line Items]
Below Market Lease, Acquired	80,603
Tractor Supply Canton GA
Real Estate Held for Investment (Details) [Line Items]
Business Acquisition, Effective Date of Acquisition	May 29, 2014
Business Acquisition, Percentage of Voting Interests Acquired	50.00%
Business Acquisition, Name of Acquired Entity	Tractor Supply Company
Business Combination, Consideration Transferred	2,212,500
Business Acquisition, Transaction Costs	27,970
Average Lease Term	7.3 years
Real Estate Revenue, Net		164,355
Gander Mountain Champaign IL \| Leases, Acquired-in-Place [Member]
Real Estate Held for Investment (Details) [Line Items]
Finite-Lived Intangible Asset, Acquired-in-Place Leases			336,209
Gander Mountain Champaign IL
Real Estate Held for Investment (Details) [Line Items]
Business Acquisition, Effective Date of Acquisition			Jul. 03, 2014
Business Acquisition, Percentage of Voting Interests Acquired			30.00%
Business Acquisition, Name of Acquired Entity			Gander Mountain
Business Combination, Consideration Transferred			2,122,500
Business Acquisition, Transaction Costs			34,052
Average Lease Term			14.9 years
Real Estate Revenue, Net				$ 167,772