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Related Party (Tables) | 6 Months Ended
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Jun. 30, 2018
Related Party [Abstract] |
Schedule of Related Party Transactions [Table Text Block] | The related payments (receipts) with related parties for the three and six months ended June 30, 2018 and 2017 (in thousands) were as follows:
| Three months ended June 30,
| 2018 |  | 2017
Receipts for trailer sales | $ | — |  |  | $ | — |
Payments for parts and services | 145 |  |  | 127 |
Terminal lease payments | 214 |  |  | 392 |
| $ | 359 |  |  | $ | 519 |
| Six months ended June 30,
| 2018 |  | 2017
Receipts for trailer sales | $ | — |  |  | $ | (12 | )
Payments for parts and services | 281 |  |  | 236 |
Terminal lease payments | 461 |  |  | 806 |
| $ | 742 |  |  | $ | 1,030 |

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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