XML 37 R22.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Inventories (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2014
Inventory Disclosure [Abstract] |
Components of Inventories | Inventories are stated at the lower of cost or market and consist of the following (in thousands):
|  | June 30, 2014 |  |  | December 31, 2013 |
Short-term inventories: |  |  |  |  |  |  |  |
Raw materials |  | $ | 46,940 |  |  | $ | 52,598 |
Work-in-process |  |  | 1,422 |  |  |  | 4,902 |
Finished goods |  |  | 13,369 |  |  |  | 49,351 |
Supplies |  |  | 2,337 |  |  |  | 3,541 |
|  |  | 64,068 |  |  |  | 110,392 |
Long-term inventories: |  |  |  |  |  |  |  |
Finished goods |  |  | 1,295 |  |  |  | 1,249 |
Total inventories |  | $ | 65,363 |  |  | $ | 111,641 |

X
- Definition Tabular disclosure of the carrying amount as of the balance sheet date of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process. Includes current and non-current inventory balances. + References No definition available. + Details
Name: | nwpx_ScheduleOfInventoryCurrentAndNonCurrentTableTextBlock
Namespace Prefix: | nwpx_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InventoryDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration