Accounts Receivable, Term

No definition available.

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Namespace Prefix:	cpa18_
Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Carrying amount as of the balance sheet date, net of allowance for doubtful accounts, of account and note receivables due from other than related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3-4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow associated with principal collections from a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

+ Details

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

- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=cpa18_PropertyLeasedtoMillsFleetFarmGroupLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=cpa18_CiprianiMember
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Balance Type:
Period Type:

Finance Receivables - Narratives (Details) $ in Thousands	3 Months Ended		12 Months Ended
Finance Receivables - Narratives (Details) $ in Thousands	Mar. 31, 2018 USD ($) property	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) property
Accounts, Notes, Loans and Financing Receivable
Notes receivable	$ 63,954		$ 66,500
Number of properties \| property	59
Proceeds from repayment of notes receivable	$ 2,546	$ 0
Property Leased to Mills Fleet Farm Group LLC
Accounts, Notes, Loans and Financing Receivable
Notes receivable	36,000		$ 38,500
Number of properties \| property			27
Proceeds from repayment of notes receivable	2,500
Cipriani
Accounts, Notes, Loans and Financing Receivable
Notes receivable	$ 28,000
Accounts receivable, term			10 years