Transactions with Del Taco - Additional Information (Detail)	3 Months Ended
Mar. 31, 2015 Acquisition
Related Party Transactions [Abstract]
Number of other partnerships formed for acquisition	3

Number of other partnerships formed for acquisition.

No definition available.

Name:	dtipiv_NumberOfOtherPartnershipsFormedForAcquisition
Namespace Prefix:	dtipiv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration