XML 47 R35.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Significant Accounting Policies Self-Insurance Accruals (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Significant Accounting Policies [Abstract] |  |
Health insurance reserves | $ 3.2 | $ 4.5

X
- Definition Self insurance health insurance reserves for estimated cost of health related claims, including estimated expenses incurred but not reported + References No definition available. + Details
Name: | htld_HealthInsuranceReserves
Namespace Prefix: | htld_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Significant Accounting Policies [Abstract] + References No definition available. + Details
Name: | htld_SignificantAccountingPoliciesAbstract
Namespace Prefix: | htld_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration