Transactions with General Partner and Its Affiliates - Amounts Paid and/or Accrued to General Partner and Its Affiliates (Detail) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Related Party Transactions [Abstract]
Management fees	$ 66,034us-gaap_ManagementFeeExpense	$ 65,049us-gaap_ManagementFeeExpense
Overhead allowance	5,327us-gaap_AdministrativeFeesExpense	5,248us-gaap_AdministrativeFeesExpense
Other outsourced administrative fees	488	1,088
Reimbursement for out-of-pocket expenses	2,500	1,162
Cash distribution	26us-gaap_GeneralPartnerDistributions	0us-gaap_GeneralPartnerDistributions
Total general partner	$ 74,375zzdd_GeneralPartnerExpenses	$ 72,547zzdd_GeneralPartnerExpenses

Amount of expense for administrative services provided to the limited liability company (LLC) or limited partnership (LP) by the managing member or general partner, affiliate of managing member or general partner, or affiliate of LLC or LP, for example, but not limited to, salaries, rent, or overhead costs.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

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

- Definition

Distributions from earnings to the general partner of a partnership included in the consolidated financial statements.

+ References

No definition available.

+ Details

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

- Definition

Amount of expenses related to the managing member or general partner for management of the day-to-day business functions of the limited liability company (LLC) or limited partnership (LP).

+ References

+ Details

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

- Definition

Professional and contract service expense includes cost reimbursements for support services related to contracted projects, outsourced management, technical and staff support.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Total general partner expenses paid by Partnership for the current period.

+ References

No definition available.

+ Details

Name:	zzdd_GeneralPartnerExpenses
Namespace Prefix:	zzdd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reimbursement for general partner's out-of-pocket expenses.

+ References

No definition available.

+ Details

Name:	zzdd_ReimbursementForOutOfPocketExpenses
Namespace Prefix:	zzdd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration