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Effect of Increase in Cost of Insurance and Claims (Detail) (USD $)
In Thousands, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 27, 2014
Dec. 28, 2013
Dec. 29, 2012
Change in Accounting Estimate [Line Items]      
Operating income $ 224,372us-gaap_OperatingIncomeLoss $ 176,590us-gaap_OperatingIncomeLoss $ 200,739us-gaap_OperatingIncomeLoss
Income from continuing operations 138,809us-gaap_IncomeLossFromContinuingOperations 108,922us-gaap_IncomeLossFromContinuingOperations 126,566us-gaap_IncomeLossFromContinuingOperations
Earnings per share from continuing operations $ 3.09us-gaap_IncomeLossFromContinuingOperationsPerBasicShare $ 2.37us-gaap_IncomeLossFromContinuingOperationsPerBasicShare $ 2.71us-gaap_IncomeLossFromContinuingOperationsPerBasicShare
Diluted earnings per share from continuing operations $ 3.07us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare $ 2.36us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare $ 2.70us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare
Development of Prior Year Self Insured Claims Estimates      
Change in Accounting Estimate [Line Items]      
Operating income 6,664us-gaap_OperatingIncomeLoss
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
10,909us-gaap_OperatingIncomeLoss
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
11us-gaap_OperatingIncomeLoss
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
Income from continuing operations $ 4,118us-gaap_IncomeLossFromContinuingOperations
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
$ 6,742us-gaap_IncomeLossFromContinuingOperations
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
$ 7us-gaap_IncomeLossFromContinuingOperations
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
Earnings per share from continuing operations $ 0.09us-gaap_IncomeLossFromContinuingOperationsPerBasicShare
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
$ 0.15us-gaap_IncomeLossFromContinuingOperationsPerBasicShare
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
 
Diluted earnings per share from continuing operations $ 0.09us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember
$ 0.15us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= lstr_DevelopmentOfPriorYearSelfInsuredClaimsEstimatesMember