Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0001562762-20-000111-index-headers.html | 2020-03-10 18:16:42 | |
| 0001562762-20-000111-index.html | 2020-03-10 18:16:42 | |
| 0001562762-20-000111.txt | 2020-03-10 18:16:42 | |
 0001562762-20-000111-xbrl.zip | 170081 | 2020-03-10 18:16:42 |
| FilingSummary.xml | 49209 | 2020-03-10 18:16:42 |
| Financial_Report.xlsx | 96512 | 2020-03-10 18:16:42 |
| npk-20191231.xml | 1981857 | 2020-03-10 18:16:42 |
| npk-20191231.xsd | 51587 | 2020-03-10 18:16:42 |
| npk-20191231x10k.htm | 2034259 | 2020-03-10 18:16:42 |
| npk-20191231xex21.htm | 9540 | 2020-03-10 18:16:42 |
| npk-20191231xex31_1.htm | 14697 | 2020-03-10 18:16:42 |
| npk-20191231xex31_2.htm | 15107 | 2020-03-10 18:16:42 |
| npk-20191231xex32_1.htm | 8054 | 2020-03-10 18:16:42 |
| npk-20191231xex32_2.htm | 8364 | 2020-03-10 18:16:42 |
| npk-20191231xex4.htm | 15151 | 2020-03-10 18:16:42 |
| npk-20191231_cal.xml | 98253 | 2020-03-10 18:16:42 |
| npk-20191231_def.xml | 163954 | 2020-03-10 18:16:42 |
| npk-20191231_lab.xml | 444888 | 2020-03-10 18:16:42 |
| npk-20191231_pre.xml | 399942 | 2020-03-10 18:16:42 |
| R1.htm | 50498 | 2020-03-10 18:16:42 |
| R10.htm | 7883 | 2020-03-10 18:16:42 |
| R11.htm | 6409 | 2020-03-10 18:16:42 |
| R12.htm | 4994 | 2020-03-10 18:16:42 |
| R13.htm | 52045 | 2020-03-10 18:16:42 |
| R14.htm | 8560 | 2020-03-10 18:16:42 |
| R15.htm | 123349 | 2020-03-10 18:16:42 |
| R16.htm | 5102 | 2020-03-10 18:16:42 |
| R17.htm | 10858 | 2020-03-10 18:16:42 |
| R18.htm | 20509 | 2020-03-10 18:16:42 |
| R19.htm | 139402 | 2020-03-10 18:16:42 |
| R2.htm | 106393 | 2020-03-10 18:16:42 |
| R20.htm | 43094 | 2020-03-10 18:16:42 |
| R21.htm | 134294 | 2020-03-10 18:16:42 |
| R22.htm | 7130 | 2020-03-10 18:16:42 |
| R23.htm | 56655 | 2020-03-10 18:16:42 |
| R24.htm | 7172 | 2020-03-10 18:16:42 |
| R25.htm | 48734 | 2020-03-10 18:16:42 |
| R26.htm | 7132 | 2020-03-10 18:16:42 |
| R27.htm | 7113 | 2020-03-10 18:16:42 |
| R28.htm | 62893 | 2020-03-10 18:16:42 |
| R29.htm | 169491 | 2020-03-10 18:16:42 |
| R3.htm | 12988 | 2020-03-10 18:16:42 |
| R30.htm | 72836 | 2020-03-10 18:16:42 |
| R31.htm | 23832 | 2020-03-10 18:16:42 |
| R32.htm | 44257 | 2020-03-10 18:16:42 |
| R33.htm | 124167 | 2020-03-10 18:16:42 |
| R34.htm | 15568 | 2020-03-10 18:16:42 |
| R35.htm | 131638 | 2020-03-10 18:16:42 |
| R36.htm | 40539 | 2020-03-10 18:16:42 |
| R37.htm | 131391 | 2020-03-10 18:16:42 |
| R38.htm | 52651 | 2020-03-10 18:16:42 |
| R39.htm | 44343 | 2020-03-10 18:16:42 |
| R4.htm | 57979 | 2020-03-10 18:16:42 |
| R40.htm | 130452 | 2020-03-10 18:16:42 |
| R41.htm | 10323 | 2020-03-10 18:16:42 |
| R42.htm | 17050 | 2020-03-10 18:16:42 |
| R43.htm | 8943 | 2020-03-10 18:16:42 |
| R44.htm | 18663 | 2020-03-10 18:16:42 |
| R45.htm | 9230 | 2020-03-10 18:16:42 |
| R46.htm | 12153 | 2020-03-10 18:16:42 |
| R47.htm | 6362 | 2020-03-10 18:16:42 |
| R48.htm | 28148 | 2020-03-10 18:16:42 |
| R49.htm | 21768 | 2020-03-10 18:16:42 |
| R5.htm | 98617 | 2020-03-10 18:16:42 |
| R50.htm | 17349 | 2020-03-10 18:16:42 |
| R51.htm | 12176 | 2020-03-10 18:16:42 |
| R52.htm | 20001 | 2020-03-10 18:16:42 |
| R53.htm | 16098 | 2020-03-10 18:16:42 |
| R54.htm | 32117 | 2020-03-10 18:16:42 |
| R55.htm | 15389 | 2020-03-10 18:16:42 |
| R56.htm | 14448 | 2020-03-10 18:16:42 |
| R57.htm | 4907 | 2020-03-10 18:16:42 |
| R58.htm | 17597 | 2020-03-10 18:16:42 |
| R59.htm | 8174 | 2020-03-10 18:16:42 |
| R6.htm | 27938 | 2020-03-10 18:16:42 |
| R60.htm | 42564 | 2020-03-10 18:16:42 |
| R61.htm | 18511 | 2020-03-10 18:16:42 |
| R62.htm | 8224 | 2020-03-10 18:16:42 |
| R63.htm | 19614 | 2020-03-10 18:16:42 |
| R64.htm | 16579 | 2020-03-10 18:16:42 |
| R65.htm | 30283 | 2020-03-10 18:16:42 |
| R66.htm | 11887 | 2020-03-10 18:16:42 |
| R67.htm | 34878 | 2020-03-10 18:16:42 |
| R68.htm | 38119 | 2020-03-10 18:16:42 |
| R69.htm | 10990 | 2020-03-10 18:16:42 |
| R7.htm | 5848 | 2020-03-10 18:16:42 |
| R70.htm | 15350 | 2020-03-10 18:16:42 |
| R71.htm | 26935 | 2020-03-10 18:16:42 |
| R72.htm | 31240 | 2020-03-10 18:16:42 |
| R73.htm | 11087 | 2020-03-10 18:16:42 |
| R74.htm | 8548 | 2020-03-10 18:16:42 |
| R75.htm | 10366 | 2020-03-10 18:16:42 |
| R76.htm | 12441 | 2020-03-10 18:16:42 |
| R8.htm | 127883 | 2020-03-10 18:16:42 |
| R9.htm | 30516 | 2020-03-10 18:16:42 |
| report.css | 2767 | 2020-03-10 18:16:42 |
| Show.js | 1085 | 2020-03-10 18:16:42 |