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

No definition available.

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- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

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

+ References

+ Details

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

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ 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)

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

+ Details

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

- 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

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current portion 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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.20)

-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, 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Line-of-Credit Arrangement

-URI http://asc.fasb.org/extlink&oid=6517033

+ Details

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

- Details

Name:	wldn_DebtByMaturityAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of short-term debt and current maturity of long-term debt. Excludes capital lease obligations.

+ References

No definition available.

+ Details

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Namespace Prefix:	wldn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the minimum tangible net worth as a percentage of actual tangible net worth for the previous financial statements received prior to the closing date of the agreement, required to be maintained by the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	wldn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of interest rate that will be increased in case of default under customary negative covenants of credit agreement.

+ References

No definition available.

+ Details

Name:	wldn_DebtInstrumentCovenantsIncreasedPercentageOfInterestRateInCaseOfDefault
Namespace Prefix:	wldn_
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Period Type:	duration

- Definition

The maximum total leverage ratio of total funded debt (measured as the sum of all obligations for borrowed money, including subordinated debt, plus all capital lease obligations) plus capital leases plus financial letters of credit to EBITDA as a covenant under the credit agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

The minimum fixed charge coverage ratio (measured as the sum of EBITDA plus rent expense less unfinanced capital expenditures divided by the sum of rent expense plus principal payments plus cash taxes plus cash interest plus restricted payments plus distributions) as a covenant under the credit agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	wldn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the step ups amount equal to as a percentage of net income (if positive) required for tangible net worth as a covenant under the credit agreement.

+ References

No definition available.

+ Details

Name:	wldn_DebtInstrumentCovenantStepUpsAmountEqualAsPercentageOfNetIncomeRequiredForTangibleNetWorth
Namespace Prefix:	wldn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of debt maturing in the next fiscal year following the latest fiscal year. Excludes capital lease obligations.

+ References

No definition available.

+ Details

Name:	wldn_DebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix:	wldn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of total consideration for all permitted acquisitions (including potential future earn-out obligations), as customary negative covenants under the credit agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	wldn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of total consideration for individual permitted acquisitions (including potential future earn-out obligations), as customary negative covenants under the credit agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	wldn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

DEBT OBLIGATIONS (Details) (USD $)				0 Months Ended			12 Months Ended			0 Months Ended	12 Months Ended	0 Months Ended				12 Months Ended
DEBT OBLIGATIONS (Details) (USD $)	Dec. 27, 2013	Dec. 28, 2012	Dec. 27, 2013 Revolving Credit Facility Wells Fargo	Mar. 24, 2014 Revolving Credit Facility Subsequent Event BMO	Mar. 24, 2014 Revolving Credit Facility Maximum Subsequent Event BMO	Dec. 28, 2012 Revolving line of credit	Dec. 27, 2013 Revolving line of credit Wells Fargo	Mar. 20, 2014 Revolving line of credit Subsequent Event Wells Fargo	Mar. 24, 2014 Revolving line of credit Subsequent Event BMO	Mar. 24, 2014 Revolving line of credit Maximum Subsequent Event BMO	Dec. 27, 2013 Revolving line of credit LIBOR Wells Fargo	Mar. 24, 2014 Revolving line of credit LIBOR Subsequent Event BMO	Mar. 24, 2014 Revolving line of credit Base rate Subsequent Event BMO	Mar. 24, 2014 Standby letter of credit sub-facility Subsequent Event BMO	Mar. 24, 2014 Secured term loan Subsequent Event BMO	Dec. 27, 2013 Notes payable for vehicles	Dec. 28, 2012 Notes payable for vehicles	Dec. 27, 2013 Notes payable for insurance	Dec. 28, 2012 Notes payable for insurance	Dec. 27, 2013 Other	Dec. 28, 2012 Other
Debt obligations
Total debt obligations, excluding capital lease obligations	$ 517,000	$ 3,628,000				$ 3,000,000										$ 7,000	$ 78,000	$ 462,000	$ 508,000	$ 48,000	$ 42,000
Less current portion	517,000	3,628,000
Outstanding balance		3,000,000	0
Maturity term																36 months	36 months	9 months	9 months
Interest rate (as a percent)																1.90%	1.90%	1.90%	1.90%
Monthly principal and interest installment (in dollars)																6,000	6,000	28,000
Maximum borrowing capacity				7,500,000			5,000,000	75,905	7,500,000					5,000,000	2,500,000
Floating interest rate, basis											LIBOR	LIBOR	base rate
Spread on floating interest rate (as a percent)											2.25%	1.75%	0.75%
Fee on unused commitments and customary fees (as a percent)							0.25%			0.30%
Maximum total leverage ratio of total funded debt to EBITDA				2.00
Minimum fixed charge coverage ratio				1.25
Minimum tangible net worth required to be maintained (as a percent)				85.00%
Step ups amount equal to net income required to be maintained (as a percent)				50.00%
Total consideration for all permitted acquisitions					2,500,000
Total consideration for individual permitted acquisitions					750,000
Percentage of increased interest rate in case of default				2.00%
Principal maturities
2014	517,000
Total debt obligations, excluding capital lease obligations	$ 517,000	$ 3,628,000				$ 3,000,000										$ 7,000	$ 78,000	$ 462,000	$ 508,000	$ 48,000	$ 42,000