Investments - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Mar. 29, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Investments maximum maturity period	5 years	5 years
Unrealized gains, net of unrealized losses, on the investments in the bond portfolio	$ 548,000	$ 378,000

Net amount of accumulated unrealized gains (losses) on investments in available-for-sale securities impacting investments. Represents the difference between the fair value and cost of investments in available-for-sale securities.

No definition available.

Name:	lstr_AvailableForSaleSecuritiesGrossUnrealizedGainLossAccumulatedInInvestments
Namespace Prefix:	lstr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant