Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000067716-20-000044-index-headers.html | 2020-08-06 09:12:09 | |
| 0000067716-20-000044-index.html | 2020-08-06 09:12:09 | |
| 0000067716-20-000044.txt | 2020-08-06 09:12:09 | |
 0000067716-20-000044-xbrl.zip | 416903 | 2020-08-06 09:12:09 |
| a2020q2ex31a.htm | 10571 | 2020-08-06 09:12:09 |
| a2020q2ex31b.htm | 10154 | 2020-08-06 09:12:09 |
| a2020q2ex32.htm | 6224 | 2020-08-06 09:12:09 |
| a2020q2ex95.htm | 186864 | 2020-08-06 09:12:09 |
| FilingSummary.xml | 47101 | 2020-08-06 09:12:09 |
| Financial_Report.xlsx | 126661 | 2020-08-06 09:12:09 |
| mdu-20200630.htm | 3893562 | 2020-08-06 09:12:09 |
| mdu-20200630.xsd | 53687 | 2020-08-06 09:12:09 |
| mdu-20200630_cal.xml | 100599 | 2020-08-06 09:12:09 |
| mdu-20200630_def.xml | 413795 | 2020-08-06 09:12:09 |
| mdu-20200630_htm.xml | 3973077 | 2020-08-06 09:12:09 |
| mdu-20200630_lab.xml | 726716 | 2020-08-06 09:12:09 |
| mdu-20200630_pre.xml | 500519 | 2020-08-06 09:12:09 |
| MetaLinks.json | 768495 | 2020-08-06 09:12:09 |
| R1.htm | 54061 | 2020-08-06 09:12:09 |
| R10.htm | 47186 | 2020-08-06 09:12:09 |
| R11.htm | 25330 | 2020-08-06 09:12:09 |
| R12.htm | 26850 | 2020-08-06 09:12:09 |
| R13.htm | 115394 | 2020-08-06 09:12:09 |
| R14.htm | 380753 | 2020-08-06 09:12:09 |
| R15.htm | 13824 | 2020-08-06 09:12:09 |
| R16.htm | 5179 | 2020-08-06 09:12:09 |
| R17.htm | 93633 | 2020-08-06 09:12:09 |
| R18.htm | 96303 | 2020-08-06 09:12:09 |
| R19.htm | 140440 | 2020-08-06 09:12:09 |
| R2.htm | 100690 | 2020-08-06 09:12:09 |
| R20.htm | 51781 | 2020-08-06 09:12:09 |
| R21.htm | 29095 | 2020-08-06 09:12:09 |
| R22.htm | 177462 | 2020-08-06 09:12:09 |
| R23.htm | 71355 | 2020-08-06 09:12:09 |
| R24.htm | 17530 | 2020-08-06 09:12:09 |
| R25.htm | 16277 | 2020-08-06 09:12:09 |
| R26.htm | 5141 | 2020-08-06 09:12:09 |
| R27.htm | 12327 | 2020-08-06 09:12:09 |
| R28.htm | 12694 | 2020-08-06 09:12:09 |
| R29.htm | 6404 | 2020-08-06 09:12:09 |
| R3.htm | 48637 | 2020-08-06 09:12:09 |
| R30.htm | 5614 | 2020-08-06 09:12:09 |
| R31.htm | 5148 | 2020-08-06 09:12:09 |
| R32.htm | 7890 | 2020-08-06 09:12:09 |
| R33.htm | 7374 | 2020-08-06 09:12:09 |
| R34.htm | 6573 | 2020-08-06 09:12:09 |
| R35.htm | 10098 | 2020-08-06 09:12:09 |
| R36.htm | 43859 | 2020-08-06 09:12:09 |
| R37.htm | 25052 | 2020-08-06 09:12:09 |
| R38.htm | 25490 | 2020-08-06 09:12:09 |
| R39.htm | 116603 | 2020-08-06 09:12:09 |
| R4.htm | 134825 | 2020-08-06 09:12:09 |
| R40.htm | 373584 | 2020-08-06 09:12:09 |
| R41.htm | 96741 | 2020-08-06 09:12:09 |
| R42.htm | 184481 | 2020-08-06 09:12:09 |
| R43.htm | 136670 | 2020-08-06 09:12:09 |
| R44.htm | 52704 | 2020-08-06 09:12:09 |
| R45.htm | 28638 | 2020-08-06 09:12:09 |
| R46.htm | 168844 | 2020-08-06 09:12:09 |
| R47.htm | 65651 | 2020-08-06 09:12:09 |
| R48.htm | 30116 | 2020-08-06 09:12:09 |
| R49.htm | 8128 | 2020-08-06 09:12:09 |
| R5.htm | 72758 | 2020-08-06 09:12:09 |
| R50.htm | 25822 | 2020-08-06 09:12:09 |
| R51.htm | 18860 | 2020-08-06 09:12:09 |
| R52.htm | 14299 | 2020-08-06 09:12:09 |
| R53.htm | 37813 | 2020-08-06 09:12:09 |
| R54.htm | 36419 | 2020-08-06 09:12:09 |
| R55.htm | 110679 | 2020-08-06 09:12:09 |
| R56.htm | 24362 | 2020-08-06 09:12:09 |
| R57.htm | 16413 | 2020-08-06 09:12:09 |
| R58.htm | 32681 | 2020-08-06 09:12:09 |
| R59.htm | 26367 | 2020-08-06 09:12:09 |
| R6.htm | 83012 | 2020-08-06 09:12:09 |
| R60.htm | 7552 | 2020-08-06 09:12:09 |
| R61.htm | 19997 | 2020-08-06 09:12:09 |
| R62.htm | 26819 | 2020-08-06 09:12:09 |
| R63.htm | 14909 | 2020-08-06 09:12:09 |
| R64.htm | 48511 | 2020-08-06 09:12:09 |
| R65.htm | 24642 | 2020-08-06 09:12:09 |
| R66.htm | 7692 | 2020-08-06 09:12:09 |
| R67.htm | 16767 | 2020-08-06 09:12:09 |
| R68.htm | 35041 | 2020-08-06 09:12:09 |
| R69.htm | 6555 | 2020-08-06 09:12:09 |
| R7.htm | 9417 | 2020-08-06 09:12:09 |
| R70.htm | 12022 | 2020-08-06 09:12:09 |
| R71.htm | 32448 | 2020-08-06 09:12:09 |
| R72.htm | 17173 | 2020-08-06 09:12:09 |
| R73.htm | 20137 | 2020-08-06 09:12:09 |
| R74.htm | 96909 | 2020-08-06 09:12:09 |
| R75.htm | 40735 | 2020-08-06 09:12:09 |
| R76.htm | 13708 | 2020-08-06 09:12:09 |
| R77.htm | 15418 | 2020-08-06 09:12:09 |
| R78.htm | 12437 | 2020-08-06 09:12:09 |
| R79.htm | 11666 | 2020-08-06 09:12:09 |
| R8.htm | 19513 | 2020-08-06 09:12:09 |
| R80.htm | 12990 | 2020-08-06 09:12:09 |
| R81.htm | 4753 | 2020-08-06 09:12:09 |
| R82.htm | 25589 | 2020-08-06 09:12:09 |
| R83.htm | 6325 | 2020-08-06 09:12:09 |
| R9.htm | 5332 | 2020-08-06 09:12:09 |
| report.css | 2767 | 2020-08-06 09:12:09 |
| Show.js | 1085 | 2020-08-06 09:12:09 |