Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0001703644-20-000072-index-headers.html | 2020-11-09 17:03:41 | |
| 0001703644-20-000072-index.html | 2020-11-09 17:03:41 | |
| 0001703644-20-000072.txt | 2020-11-09 17:03:41 | |
 0001703644-20-000072-xbrl.zip | 365975 | 2020-11-09 17:03:41 |
| FilingSummary.xml | 45097 | 2020-11-09 17:03:41 |
| Financial_Report.xlsx | 127487 | 2020-11-09 17:03:41 |
| gpmt-20200930.htm | 2994679 | 2020-11-09 17:03:41 |
| gpmt-20200930.xsd | 59866 | 2020-11-09 17:03:41 |
| gpmt-20200930_cal.xml | 96533 | 2020-11-09 17:03:41 |
| gpmt-20200930_def.xml | 241255 | 2020-11-09 17:03:41 |
| gpmt-20200930_htm.xml | 2029973 | 2020-11-09 17:03:41 |
| gpmt-20200930_lab.xml | 660936 | 2020-11-09 17:03:41 |
| gpmt-20200930_pre.xml | 442733 | 2020-11-09 17:03:41 |
| gpmtexh93020311.htm | 11400 | 2020-11-09 17:03:41 |
| gpmtexh93020312.htm | 11229 | 2020-11-09 17:03:41 |
| gpmtexh93020321.htm | 6062 | 2020-11-09 17:03:41 |
| gpmtexh93020322.htm | 6203 | 2020-11-09 17:03:41 |
| MetaLinks.json | 676280 | 2020-11-09 17:03:41 |
| R1.htm | 52235 | 2020-11-09 17:03:41 |
| R10.htm | 187385 | 2020-11-09 17:03:41 |
| R11.htm | 14763 | 2020-11-09 17:03:41 |
| R12.htm | 11976 | 2020-11-09 17:03:41 |
| R13.htm | 12331 | 2020-11-09 17:03:41 |
| R14.htm | 66109 | 2020-11-09 17:03:41 |
| R15.htm | 129210 | 2020-11-09 17:03:41 |
| R16.htm | 11708 | 2020-11-09 17:03:41 |
| R17.htm | 6999 | 2020-11-09 17:03:41 |
| R18.htm | 129247 | 2020-11-09 17:03:41 |
| R19.htm | 18304 | 2020-11-09 17:03:41 |
| R2.htm | 82813 | 2020-11-09 17:03:41 |
| R20.htm | 5809 | 2020-11-09 17:03:41 |
| R21.htm | 32740 | 2020-11-09 17:03:41 |
| R22.htm | 23793 | 2020-11-09 17:03:41 |
| R23.htm | 5615 | 2020-11-09 17:03:41 |
| R24.htm | 8609 | 2020-11-09 17:03:41 |
| R25.htm | 42320 | 2020-11-09 17:03:41 |
| R26.htm | 12523 | 2020-11-09 17:03:41 |
| R27.htm | 8011 | 2020-11-09 17:03:41 |
| R28.htm | 52702 | 2020-11-09 17:03:41 |
| R29.htm | 20435 | 2020-11-09 17:03:41 |
| R3.htm | 35718 | 2020-11-09 17:03:41 |
| R30.htm | 22015 | 2020-11-09 17:03:41 |
| R31.htm | 186883 | 2020-11-09 17:03:41 |
| R32.htm | 13928 | 2020-11-09 17:03:41 |
| R33.htm | 11924 | 2020-11-09 17:03:41 |
| R34.htm | 10237 | 2020-11-09 17:03:41 |
| R35.htm | 52351 | 2020-11-09 17:03:41 |
| R36.htm | 117393 | 2020-11-09 17:03:41 |
| R37.htm | 14437 | 2020-11-09 17:03:41 |
| R38.htm | 30190 | 2020-11-09 17:03:41 |
| R39.htm | 18527 | 2020-11-09 17:03:41 |
| R4.htm | 111922 | 2020-11-09 17:03:41 |
| R40.htm | 38822 | 2020-11-09 17:03:41 |
| R41.htm | 45903 | 2020-11-09 17:03:41 |
| R42.htm | 39277 | 2020-11-09 17:03:41 |
| R43.htm | 39519 | 2020-11-09 17:03:41 |
| R44.htm | 21536 | 2020-11-09 17:03:41 |
| R45.htm | 19045 | 2020-11-09 17:03:41 |
| R46.htm | 27079 | 2020-11-09 17:03:41 |
| R47.htm | 18035 | 2020-11-09 17:03:41 |
| R48.htm | 4219 | 2020-11-09 17:03:41 |
| R49.htm | 45903 | 2020-11-09 17:03:41 |
| R5.htm | 140738 | 2020-11-09 17:03:41 |
| R50.htm | 18225 | 2020-11-09 17:03:41 |
| R51.htm | 13636 | 2020-11-09 17:03:41 |
| R52.htm | 17543 | 2020-11-09 17:03:41 |
| R53.htm | 17523 | 2020-11-09 17:03:41 |
| R54.htm | 41799 | 2020-11-09 17:03:41 |
| R55.htm | 55348 | 2020-11-09 17:03:41 |
| R56.htm | 23544 | 2020-11-09 17:03:41 |
| R57.htm | 28555 | 2020-11-09 17:03:41 |
| R58.htm | 6110 | 2020-11-09 17:03:41 |
| R59.htm | 30281 | 2020-11-09 17:03:41 |
| R6.htm | 93772 | 2020-11-09 17:03:41 |
| R60.htm | 35914 | 2020-11-09 17:03:41 |
| R61.htm | 12123 | 2020-11-09 17:03:41 |
| R62.htm | 20481 | 2020-11-09 17:03:41 |
| R63.htm | 6087 | 2020-11-09 17:03:41 |
| R64.htm | 16317 | 2020-11-09 17:03:41 |
| R65.htm | 24829 | 2020-11-09 17:03:41 |
| R66.htm | 15264 | 2020-11-09 17:03:41 |
| R67.htm | 4149 | 2020-11-09 17:03:41 |
| R68.htm | 20085 | 2020-11-09 17:03:41 |
| R69.htm | 10718 | 2020-11-09 17:03:41 |
| R7.htm | 7519 | 2020-11-09 17:03:41 |
| R70.htm | 10164 | 2020-11-09 17:03:41 |
| R71.htm | 19684 | 2020-11-09 17:03:41 |
| R72.htm | 26856 | 2020-11-09 17:03:41 |
| R73.htm | 3916 | 2020-11-09 17:03:41 |
| R74.htm | 48749 | 2020-11-09 17:03:41 |
| R75.htm | 18434 | 2020-11-09 17:03:41 |
| R76.htm | 11851 | 2020-11-09 17:03:41 |
| R8.htm | 45135 | 2020-11-09 17:03:41 |
| R9.htm | 20013 | 2020-11-09 17:03:41 |
| report.css | 2767 | 2020-11-09 17:03:41 |
| Show.js | 1085 | 2020-11-09 17:03:41 |