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The advisor's preferred non-compounded cumulative distribution return per annum.

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The amount of shareholder servicing fees incurred for Class C shares.

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Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

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Amount of each individual error being corrected in the correcting adjustment.

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-Subparagraph (SAB TOPIC 1.N.Q3)

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A tax based on the assessed value of real estate by the local government. The tax is usually based on the value of property (including the land).

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Summary of Significant Accounting Policies (Narratives) (Details) (USD $)	12 Months Ended		3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Real estate tax expense	$ 3,500,000us-gaap_RealEstateTaxExpense
Basis of Presentation
Preferred Return	5.00%cpa18_PreferredReturn
Shareholder servicing fee	814,000cpa18_ShareholderServicingFeeIncurred	46,000cpa18_ShareholderServicingFeeIncurred
Class A
Basis of Presentation
Loss on foreign currency transaction	400,000	100,000
Net loss
Basis of Presentation
Revision adjustment			(3,000,000)	(100,000)	(500,000)
Foreign currency gain (loss) \| Net loss
Basis of Presentation
Revision adjustment			(3,000,000)	(400,000)	(200,000)
Foreign currency gain (loss) \| Comprehensive loss
Basis of Presentation
Revision adjustment			3,000,000	400,000	200,000
Provision for income taxes
Basis of Presentation
Revision adjustment				$ (300,000)	$ 300,000