Obligation to General Partner - Additional Information (Detail)	12 Months Ended
Dec. 31, 2012
Schedule Of Performance Fees And Allocations To General Partner [Line Items]
Percentage of general partner's fee	5.00%

Percent Of Incentive Distributions To General Partners

No definition available.

Name:	dtrpiii_PercentOfIncentiveDistributionsToGeneralPartners
Namespace Prefix:	dtrpiii_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration