Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0001628280-20-016328-index-headers.html | 2020-11-12 16:45:29 | |
| 0001628280-20-016328-index.html | 2020-11-12 16:45:29 | |
| 0001628280-20-016328.txt | 2020-11-12 16:45:29 | |
 0001628280-20-016328-xbrl.zip | 301232 | 2020-11-12 16:45:29 |
| exhibit311q320.htm | 12751 | 2020-11-12 16:45:29 |
| exhibit312q320.htm | 12657 | 2020-11-12 16:45:29 |
| exhibit321q320.htm | 7189 | 2020-11-12 16:45:29 |
| exhibit322q320.htm | 7239 | 2020-11-12 16:45:29 |
| FilingSummary.xml | 28595 | 2020-11-12 16:45:29 |
| Financial_Report.xlsx | 83270 | 2020-11-12 16:45:29 |
| MetaLinks.json | 551761 | 2020-11-12 16:45:29 |
| opc-20200930.htm | 1471621 | 2020-11-12 16:45:29 |
| opc-20200930.xsd | 74964 | 2020-11-12 16:45:29 |
| opc-20200930_cal.xml | 141931 | 2020-11-12 16:45:29 |
| opc-20200930_def.xml | 230951 | 2020-11-12 16:45:29 |
 opc-20200930_g1.jpg | 14876 | 2020-11-12 16:45:29 |
| opc-20200930_htm.xml | 1498315 | 2020-11-12 16:45:29 |
| opc-20200930_lab.xml | 701483 | 2020-11-12 16:45:29 |
| opc-20200930_pre.xml | 395440 | 2020-11-12 16:45:29 |
| 459596 | 2020-11-12 16:45:29 | |
| R1.htm | 46049 | 2020-11-12 16:45:29 |
| R10.htm | 7833 | 2020-11-12 16:45:29 |
| R11.htm | 32721 | 2020-11-12 16:45:29 |
| R12.htm | 189984 | 2020-11-12 16:45:29 |
| R13.htm | 8907 | 2020-11-12 16:45:29 |
| R14.htm | 5355 | 2020-11-12 16:45:29 |
| R15.htm | 42990 | 2020-11-12 16:45:29 |
| R16.htm | 5048 | 2020-11-12 16:45:29 |
| R17.htm | 21038 | 2020-11-12 16:45:29 |
| R18.htm | 40641 | 2020-11-12 16:45:29 |
| R19.htm | 5934 | 2020-11-12 16:45:29 |
| R2.htm | 101920 | 2020-11-12 16:45:29 |
| R20.htm | 7628 | 2020-11-12 16:45:29 |
| R21.htm | 106905 | 2020-11-12 16:45:29 |
| R22.htm | 48250 | 2020-11-12 16:45:29 |
| R23.htm | 32132 | 2020-11-12 16:45:29 |
| R24.htm | 20336 | 2020-11-12 16:45:29 |
| R25.htm | 99289 | 2020-11-12 16:45:29 |
| R26.htm | 42151 | 2020-11-12 16:45:29 |
| R27.htm | 23168 | 2020-11-12 16:45:29 |
| R28.htm | 4177 | 2020-11-12 16:45:29 |
| R29.htm | 98451 | 2020-11-12 16:45:29 |
| R3.htm | 46933 | 2020-11-12 16:45:29 |
| R30.htm | 9276 | 2020-11-12 16:45:29 |
| R31.htm | 22760 | 2020-11-12 16:45:29 |
| R32.htm | 15613 | 2020-11-12 16:45:29 |
| R33.htm | 16116 | 2020-11-12 16:45:29 |
| R34.htm | 36515 | 2020-11-12 16:45:29 |
| R35.htm | 26674 | 2020-11-12 16:45:29 |
| R36.htm | 14802 | 2020-11-12 16:45:29 |
| R37.htm | 21165 | 2020-11-12 16:45:29 |
| R38.htm | 28006 | 2020-11-12 16:45:29 |
| R39.htm | 25765 | 2020-11-12 16:45:29 |
| R4.htm | 11123 | 2020-11-12 16:45:29 |
| R40.htm | 75813 | 2020-11-12 16:45:29 |
| R41.htm | 10354 | 2020-11-12 16:45:29 |
| R42.htm | 65459 | 2020-11-12 16:45:29 |
| R43.htm | 42766 | 2020-11-12 16:45:29 |
| R44.htm | 7917 | 2020-11-12 16:45:29 |
| R45.htm | 12800 | 2020-11-12 16:45:29 |
| R46.htm | 14362 | 2020-11-12 16:45:29 |
| R47.htm | 60783 | 2020-11-12 16:45:29 |
| R48.htm | 45840 | 2020-11-12 16:45:29 |
| R5.htm | 96677 | 2020-11-12 16:45:29 |
| R6.htm | 6962 | 2020-11-12 16:45:29 |
| R7.htm | 114963 | 2020-11-12 16:45:29 |
| R8.htm | 47860 | 2020-11-12 16:45:29 |
| R9.htm | 33491 | 2020-11-12 16:45:29 |
| report.css | 2767 | 2020-11-12 16:45:29 |
| Show.js | 1085 | 2020-11-12 16:45:29 |