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Property, Equipment, and Depreciation (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Property, Plant and Equipment [Line Items]    
Amortization Period of Tires 2 years  
Tractors    
Property, Plant and Equipment [Line Items]    
Property, Plant, and Equipment, Salvage Value $ 15,000us-gaap_PropertyPlantAndEquipmentSalvageValue
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= htld_TractorsMember
 
Trailers    
Property, Plant and Equipment [Line Items]    
Property, Plant, and Equipment, Salvage Value 4,000us-gaap_PropertyPlantAndEquipmentSalvageValue
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= htld_TrailersMember
 
Communications and Utilities Expense    
Property, Plant and Equipment [Line Items]    
Depreciation $ 300,000us-gaap_Depreciation
/ htld_FinancialStatementLocationAxis
= htld_CommunicationsAndUtilitiesExpenseMember
$ 300,000us-gaap_Depreciation
/ htld_FinancialStatementLocationAxis
= htld_CommunicationsAndUtilitiesExpenseMember