XML 13 R48.htm IDEA: XBRL DOCUMENT v3.2.0.727

Note 14 - Goodwill (Details Textual) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Water Transmission Group [Member]
Goodwill		$ 5,300
Goodwill		$ 5,282

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 50



-Paragraph 1



-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267



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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 45



-Paragraph 1



-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nwpx_WaterTransmissionGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: