Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000799233-21-000064-index-headers.html | 2021-11-30 17:40:51 | |
| 0000799233-21-000064-index.html | 2021-11-30 17:40:51 | |
| 0000799233-21-000064.txt | 2021-11-30 17:40:51 | |
 0000799233-21-000064-xbrl.zip | 46021 | 2021-11-30 17:40:51 |
| exhibit231consentofindepen.htm | 2051 | 2021-11-30 17:40:51 |
| exhibit311202010ka.htm | 5706 | 2021-11-30 17:40:51 |
| exhibit312202010ka.htm | 5748 | 2021-11-30 17:40:51 |
| FilingSummary.xml | 2017 | 2021-11-30 17:40:51 |
| Financial_Report.xlsx | 6208 | 2021-11-30 17:40:51 |
| htld-20201231.htm | 56811 | 2021-11-30 17:40:51 |
| htld-20201231.xsd | 13689 | 2021-11-30 17:40:51 |
| htld-20201231_cal.xml | 19905 | 2021-11-30 17:40:51 |
| htld-20201231_def.xml | 58504 | 2021-11-30 17:40:51 |
| htld-20201231_htm.xml | 20663 | 2021-11-30 17:40:51 |
| htld-20201231_lab.xml | 165723 | 2021-11-30 17:40:51 |
| htld-20201231_pre.xml | 92060 | 2021-11-30 17:40:51 |
| MetaLinks.json | 163785 | 2021-11-30 17:40:51 |
| R1.htm | 63582 | 2021-11-30 17:40:51 |
| report.css | 2767 | 2021-11-30 17:40:51 |
| Show.js | 1085 | 2021-11-30 17:40:51 |