XML 19 R9.htm IDEA: XBRL DOCUMENT
v3.20.1

Use of Estimates | 3 Months Ended
--- | ---
Mar. 31, 2020
Use of Estimates [Abstract] |
Use of Estimates | Use of EstimatesThe preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. There were no significant changes in estimates and assumptions used by management related to our critical accounting policies during the three months ended March 31, 2020.

X
- Definition Use of Estimates [Abstract] + References No definition available. + Details
Name: | htld_UseofEstimatesAbstract
Namespace Prefix: | htld_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for all significant accounting policies of the reporting entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -URI http://asc.fasb.org/topic&trid=2122369 + Details
Name: | us-gaap_SignificantAccountingPoliciesTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration