Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Operating Revenue	$ 187,523us-gaap_Revenues	$ 224,481us-gaap_Revenues
Operating Expenses
Salaries, wages, and benefits	70,996us-gaap_LaborAndRelatedExpense	70,945us-gaap_LaborAndRelatedExpense
Rent and purchased transportation	9,327htld_RentAndPurchasedTransportation	14,510htld_RentAndPurchasedTransportation
Fuel	34,256us-gaap_FuelCosts	63,225us-gaap_FuelCosts
Operations and maintenance	8,134us-gaap_CostOfServicesMaintenanceCosts	10,121us-gaap_CostOfServicesMaintenanceCosts
Operating taxes and licenses	4,813	4,846
Insurance and claims	6,644	7,095
Communications and utilities	1,543	1,830
Depreciation and amortization	25,974	24,573
Other operating expenses	7,757us-gaap_OtherCostAndExpenseOperating	8,691us-gaap_OtherCostAndExpenseOperating
Gain on disposal of property and equipment	(10,181)us-gaap_GainLossOnDispositionOfAssets	(2,043)us-gaap_GainLossOnDispositionOfAssets
Total operating expenses	159,263us-gaap_CostsAndExpenses	203,793us-gaap_CostsAndExpenses
Operating income	28,260us-gaap_OperatingIncomeLoss	20,688us-gaap_OperatingIncomeLoss
Interest income	31us-gaap_InvestmentIncomeInterest	36us-gaap_InvestmentIncomeInterest
Interest expense	(19)us-gaap_InterestExpenseDebt	(155)us-gaap_InterestExpenseDebt
Income before income taxes	28,272	20,569
Federal and state income taxes	10,661us-gaap_IncomeTaxExpenseBenefit	6,490us-gaap_IncomeTaxExpenseBenefit
Net income	17,611us-gaap_NetIncomeLoss	14,079us-gaap_NetIncomeLoss
Other comprehensive income, net of tax	0	0
Comprehensive income	$ 17,611us-gaap_ComprehensiveIncomeNetOfTax	$ 14,079us-gaap_ComprehensiveIncomeNetOfTax
Net income per share
Basic	$ 0.20us-gaap_EarningsPerShareBasic	$ 0.16us-gaap_EarningsPerShareBasic
Diluted	$ 0.20us-gaap_EarningsPerShareDiluted	$ 0.16us-gaap_EarningsPerShareDiluted
Weighted average shares outstanding
Basic	87,791	87,704
Diluted	87,965	87,917
Dividends declared per share	$ 0.02	$ 0.02

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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