XML 101 R87.htm IDEA: XBRL DOCUMENT v3.3.1.900

Note 18 - Related Party Transaction (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($)
Eagle Asset Management, Inc. [Member]
Related Party Transaction, Amounts of Transaction	$ 1.2
Raymond James & Associates [Member]
Related Party Transaction, Percentage Owned By Related Party	10.00%

X

- Definition

Related party transaction percentage owned by related party.

+ References

No definition available.

+ Details

Name:	nwpx_RelatedPartyTransactionPercentageOwnedByRelatedParty
Namespace Prefix:	nwpx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

+ Details

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

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nwpx_EagleAssetManagementIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nwpx_RaymondJamesAssociatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: