Transactions with General Partner and its Affiliates - Amounts paid and/or accrued to the General Partner and its Affiliates (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
Management fees	$ 262,086us-gaap_ManagementFeeExpense	$ 258,060us-gaap_ManagementFeeExpense	$ 252,344us-gaap_ManagementFeeExpense
Restoration fees	0zzdd_RestorationFees	0zzdd_RestorationFees	40zzdd_RestorationFees
Overhead allowance	21,142us-gaap_AdministrativeFeesExpense	20,820us-gaap_AdministrativeFeesExpense	20,356us-gaap_AdministrativeFeesExpense
Advisory fee on sale	0zzdd_AdvisoryFeeOnSale	16,296zzdd_AdvisoryFeeOnSale	0zzdd_AdvisoryFeeOnSale
Outsourced XBRL Fees	2,513	6,038	6,200
Leasing commissions	8,746us-gaap_LeasingCommissionsExpense	6,160us-gaap_LeasingCommissionsExpense	8,405us-gaap_LeasingCommissionsExpense
Reimbursement for out-of-pocket expenses	4,123	5,285	6,849
Cash distribution	3,589us-gaap_GeneralPartnerDistributions	4,176us-gaap_GeneralPartnerDistributions	2,878us-gaap_GeneralPartnerDistributions
Total general partner	$ 302,199zzdd_GeneralPartnerExpenses	$ 316,835zzdd_GeneralPartnerExpenses	$ 297,072zzdd_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

Name:	us-gaap_AdministrativeFeesExpense
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 commissions expense incurred because the lessor of real estate obtained a lessee for a rental property through a real estate agent.

+ References

No definition available.

+ Details

Name:	us-gaap_LeasingCommissionsExpense
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

Advisory fee on sale.

+ References

No definition available.

+ Details

Name:	zzdd_AdvisoryFeeOnSale
Namespace Prefix:	zzdd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

- Definition

Cash payments received from former General Partner affiliates.

+ References

No definition available.

+ Details

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