Condensed Consolidated Balance Sheets (Parentheticals) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Acquisition Fees, Accumulated Amortization	$ 15,255	$ 34,844
Property Purchase Costs, Accumulated Amortization	$ 55,418	$ 67,421

Accumulated Amortization of Deferred Reimbursement Acquisition Costs

No definition available.

Name:	crpiv_AccumulatedAmortizationOfDeferredReimbursementAcquisitionCosts
Namespace Prefix:	crpiv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant