ACCRUED LIABILITIES (Details) (USD $)	Jan. 02, 2015	Dec. 27, 2013
ACCRUED LIABILITIES
Accrued bonuses	$ 1,450,000us-gaap_AccruedBonusesCurrent	$ 31,000us-gaap_AccruedBonusesCurrent
Paid leave bank	1,404,000us-gaap_AccruedVacationCurrent	1,243,000us-gaap_AccruedVacationCurrent
Compensation and payroll taxes	1,371,000wldn_CompensationAndPayrollTaxesCurrent	749,000wldn_CompensationAndPayrollTaxesCurrent
Accrued legal	556,000us-gaap_AccruedProfessionalFeesCurrent	356,000us-gaap_AccruedProfessionalFeesCurrent
Accrued workers' compensation insurance	192,000	141,000
Accrued rent	149,000us-gaap_AccruedRentCurrent	367,000us-gaap_AccruedRentCurrent
Employee withholdings	637,000wldn_EmployeeWithholdings	343,000wldn_EmployeeWithholdings
Client deposits	79,000us-gaap_CustomerDepositsCurrent	232,000us-gaap_CustomerDepositsCurrent
Unvouchered accounts payable	4,462,000wldn_UnvoucheredAccountPayableCurrent	2,282,000wldn_UnvoucheredAccountPayableCurrent
Other	368,000us-gaap_OtherAccruedLiabilitiesCurrent	64,000us-gaap_OtherAccruedLiabilitiesCurrent
Total accrued liabilities	$ 10,668,000us-gaap_AccruedLiabilitiesCurrent	$ 5,808,000us-gaap_AccruedLiabilitiesCurrent

Carrying value as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to employees and directors or earned by them based on the terms of one or more relevant arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Current Liabilities

-URI http://asc.fasb.org/extlink&oid=6509677

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765

Reference 4: 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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6911-107765

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for contractual rent under lease arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable for unused vacation time owed to employees based on the entity's vacation benefit given to its employees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Definition

The current portion of money or property received from customers which is either to be returned upon satisfactory contract completion or applied to customer receivables in accordance with the terms of the contract or the understandings.

+ 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

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations and payables pertaining to claims incurred of a workers compensation nature. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

+ Details

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

- Definition

Represents the carrying value as of the balance sheet date of obligations incurred and payable for statutory payroll taxes incurred through that date and obligations and payables pertaining to compensation to employees.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet of the withholding of payables of employees.

+ References

No definition available.

+ Details

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

- Definition

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have not been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

+ Details

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