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v3.19.2

Related Party (Tables) | 6 Months Ended
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Jun. 30, 2019
Related Party [Abstract] |
Schedule of Related Party Transactions [Table Text Block] | The payments with related parties for the three and six months ended June 30, 2019 and 2018 (in thousands) were as follows:
| Three months ended June 30,
| 2019 |  | 2018
Payments for parts and services | $ | 145 |  |  | $ | 145 |
Terminal lease payments | — |  |  | 214 |
| $ | 145 |  |  | $ | 359 |
| Six months ended June 30,
| 2019 |  | 2018
Payments for parts and services | $ | 225 |  |  | $ | 281 |
Terminal lease payments | — |  |  | 461 |
| $ | 225 |  |  | $ | 742 |

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- Definition Related Party [Abstract] + References No definition available. + Details
Name: | htld_RelatedPartyAbstract
Namespace Prefix: | htld_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Tabular disclosure of related party transactions. Examples of related party transactions include, but are not limited to, transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners and (d) affiliates. + References No definition available. + Details
Name: | us-gaap_ScheduleOfRelatedPartyTransactionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration