v2.4.1.9

Revolving Credit Loans - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 28, 2015	Dec. 27, 2014	Sep. 10, 2013
Debt Instrument [Line Items]
Revolving line of credit loan and security agreement	$ 8,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Revolving credit loans available	3,605,535us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Letters of credit, outstanding	65,000us-gaap_LettersOfCreditOutstandingAmount
Amount drawn by the beneficiaries on irrevocable letters of credit	0dvly_AmountDrawnByBeneficiariesOnIrrevocableLettersOfCredit
Display Model LOC [Member]
Debt Instrument [Line Items]
Revolving line of credit loan and security agreement			5,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember
Term of credit facility	2 years
Variable interest rate above LIBOR	4.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember
Revolving line of credit loan and security agreement	4.179%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember	4.154%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember
Revolving credit loan outstanding balance	0us-gaap_LineOfCredit / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember	0us-gaap_LineOfCredit / us-gaap_CreditFacilityAxis = dvly_DisplayModelLocMember
Working Capital LOC [Member]
Debt Instrument [Line Items]
Term of credit facility	2 years
Variable interest rate above LIBOR	2.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = dvly_WorkingCapitalLocMember
Revolving line of credit loan and security agreement	2.679%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_CreditFacilityAxis = dvly_WorkingCapitalLocMember	2.654%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_CreditFacilityAxis = dvly_WorkingCapitalLocMember
Revolving credit loan outstanding balance	$ 0us-gaap_LineOfCredit / us-gaap_CreditFacilityAxis = dvly_WorkingCapitalLocMember	$ 0us-gaap_LineOfCredit / us-gaap_CreditFacilityAxis = dvly_WorkingCapitalLocMember

X

- Definition

Amount drawn by beneficiaries on irrevocable letters of credit.

+ References

No definition available.

+ Details

Name:	dvly_AmountDrawnByBeneficiariesOnIrrevocableLettersOfCredit
Namespace Prefix:	dvly_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

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

X

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_CreditFacilityAxis=dvly_DisplayModelLocMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CreditFacilityAxis=dvly_WorkingCapitalLocMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: