Name:	cpa18_DeferredAcquisitionRevenueReceived
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of organization costs paid by our advisor on our behalf.

No definition available.

Name:	cpa18_OrganizationCostsPaidByAffiliate
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Total cash payment made to the advisor for asset acquisitions during the reporting period for structuring transactions on behalf of the reporting entity.

No definition available.

Name:	cpa18_PaymentOfDeferredAcquisitionFeesToAffiliate
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The net realized foreign currency transaction and other gains or losses (pretax) included in determining net income from transactions that were settled as of the balance sheet date.

No definition available.

Name:	cpa18_RealizedGainLossOnForeignCurrencyTransactionsAndOther
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of the adjustment to rental revenues to measure escalating leasing revenues on a straight line basis and amount of non-cash amortization of intangible asset (liability) for above and below market leases.

No definition available.

Name:	cpa18_StraightLineRentAdjustmentsAndAmortizationOfRentRelatedIntangibles
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Value added tax paid in connection with investments in foreign properties.

No definition available.

Name:	cpa18_VatPaidInConnectionWithAcquisitionOfRealEstate
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

VAT refunded to the Company in connection with acquisitions in real estate.

No definition available.

Name:	cpa18_VatRefundedInConnectionWithAcquisitionsInRealEstate
Namespace Prefix:	cpa18_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3044-108585

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

Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 830

-SubTopic 230

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6450594&loc=d3e33268-110906

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

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

The aggregate net amount of depreciation, amortization, and accretion recognized during an accounting period. As a noncash item, the net amount is added back to net income when calculating cash provided by or used in operations using the indirect method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 830

-SubTopic 230

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6450594&loc=d3e33268-110906

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

The increase (decrease) during the reporting period in other assets used in operating activities less other operating liabilities used in operating activities not separately disclosed in the statement of cash flows. May include changes in other current assets and liabilities, other noncurrent assets and liabilities, or a combination of other current and noncurrent assets and liabilities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as investing activities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

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

Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 26

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3574-108585

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

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

Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 26

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3574-108585

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

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

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

Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

Name:	us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

Net cash outflow or inflow from other deposits that are not separately disclosed.

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

The cash outflow to reacquire common stock during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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

The cash outflow for loan and debt issuance costs.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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

The cash outflow associated with the purchase of real estate held-for-investment and real estate joint ventures.

No definition available.

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

The cash outflow for the purchase of a retained interest in a receivable securitized via a structured process whereby interests in loans and other receivables are packaged, underwritten, and sold in the form of asset-backed securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

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

Amount of cash outflow to a noncontrolling interest. Includes, but not limited to, reduction of noncontrolling interest ownership. Excludes dividends paid to the noncontrolling interest.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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

The cash inflow from the additional capital contribution to the entity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

No definition available.

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

The cash inflow from amounts received from issuance of long-term debt that is wholly or partially secured by collateral. Excludes proceeds from tax exempt secured debt.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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

Amount of cash inflow from a noncontrolling interest. Includes, but is not limited to, purchase of additional shares or other increase in noncontrolling interest ownership.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

The cash inflow from a long-term borrowing made from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth. Alternate caption: Proceeds from Advances from Affiliates.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4K

-URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591552-111686

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4J

-URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591551-111686

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

The cash outflow for the payment of a long-term borrowing made from a related party where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth. Alternate caption: Payments for Advances from Affiliates.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

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

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585