Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000080172-18-000034-index-headers.html | 2018-08-10 16:03:01 | |
| 0000080172-18-000034-index.html | 2018-08-10 16:03:01 | |
| 0000080172-18-000034.txt | 2018-08-10 16:03:01 | |
 0000080172-18-000034-xbrl.zip | 62824 | 2018-08-10 16:03:01 |
| FilingSummary.xml | 18988 | 2018-08-10 16:03:01 |
| Financial_Report.xlsx | 36270 | 2018-08-10 16:03:01 |
| npk-20180701.xml | 722566 | 2018-08-10 16:03:01 |
| npk-20180701.xsd | 19061 | 2018-08-10 16:03:01 |
| npk-20180701x10q.htm | 859592 | 2018-08-10 16:03:01 |
| npk-20180701xex31_1.htm | 15363 | 2018-08-10 16:03:01 |
| npk-20180701xex31_2.htm | 15644 | 2018-08-10 16:03:01 |
| npk-20180701xex32_1.htm | 8866 | 2018-08-10 16:03:01 |
| npk-20180701xex32_2.htm | 9063 | 2018-08-10 16:03:01 |
| npk-20180701_cal.xml | 51135 | 2018-08-10 16:03:01 |
| npk-20180701_def.xml | 63153 | 2018-08-10 16:03:01 |
| npk-20180701_lab.xml | 175677 | 2018-08-10 16:03:01 |
| npk-20180701_pre.xml | 160831 | 2018-08-10 16:03:01 |
| R1.htm | 21939 | 2018-08-10 16:03:01 |
| R10.htm | 157477 | 2018-08-10 16:03:01 |
| R11.htm | 7755 | 2018-08-10 16:03:01 |
| R12.htm | 61301 | 2018-08-10 16:03:01 |
| R13.htm | 5538 | 2018-08-10 16:03:01 |
| R14.htm | 5076 | 2018-08-10 16:03:01 |
| R15.htm | 71957 | 2018-08-10 16:03:01 |
| R16.htm | 8699 | 2018-08-10 16:03:01 |
| R17.htm | 157397 | 2018-08-10 16:03:01 |
| R18.htm | 54998 | 2018-08-10 16:03:01 |
| R19.htm | 70451 | 2018-08-10 16:03:01 |
| R2.htm | 93161 | 2018-08-10 16:03:01 |
| R20.htm | 8123 | 2018-08-10 16:03:01 |
| R21.htm | 22010 | 2018-08-10 16:03:01 |
| R22.htm | 10675 | 2018-08-10 16:03:01 |
| R23.htm | 27563 | 2018-08-10 16:03:01 |
| R24.htm | 29422 | 2018-08-10 16:03:01 |
| R25.htm | 15103 | 2018-08-10 16:03:01 |
| R26.htm | 8349 | 2018-08-10 16:03:01 |
| R27.htm | 25380 | 2018-08-10 16:03:01 |
| R28.htm | 32355 | 2018-08-10 16:03:01 |
| R29.htm | 24158 | 2018-08-10 16:03:01 |
| R3.htm | 8496 | 2018-08-10 16:03:01 |
| R4.htm | 53363 | 2018-08-10 16:03:01 |
| R5.htm | 72109 | 2018-08-10 16:03:01 |
| R6.htm | 7885 | 2018-08-10 16:03:01 |
| R7.htm | 5123 | 2018-08-10 16:03:01 |
| R8.htm | 16919 | 2018-08-10 16:03:01 |
| R9.htm | 5011 | 2018-08-10 16:03:01 |
| report.css | 2767 | 2018-08-10 16:03:01 |
| Show.js | 1410 | 2018-08-10 16:03:01 |