Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION PLAN (Various Option Plans and Options Outstanding) (Details)

v2.4.1.9
STOCK-BASED COMPENSATION PLAN (Various Option Plans and Options Outstanding) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended
Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]  
Number of options outstanding, beginning balance 568,818us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Options granted 12,150us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Exercised (85,235)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Forfeited (4,500)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
Number of options outstanding, ending balance 491,233us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]  
Weighted average exercise price per option, outstanding, beginning balance (dollars per share) $ 13.40us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Weighted average exercise price per option granted (dollars per share) $ 57.37us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Weighted average exercise price per option exercised (dollars per share) $ 9.04us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Weighted average exercise price per option forfeited (dollars per share) $ 8.42us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Weighted average exercise price per option, outstanding, ending balance (dollars per share) $ 15.29us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]  
Weighted average remaining contractual term of options outstanding (in years) 3 years 4 months 24 days
Aggregate intrinsic value of options outstanding $ 27.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Options vested and expected to vest (shares) 491,233us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
Options, vested and expected to vest weighted average exercise price (in dollars per share) $ 15.29us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
Weighted average remaining contractual term, vested and expected to vest options (in years) 3 years 4 months 24 days
Aggregate intrinsic value, vested and expected to vest options 27.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
Options exercisable at end of period (shares) 491,233us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
Options exercisable at end of period, weighted average exercise price $ 15.29us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
Options exercisable at end of period, weighted average remaining term 3 years 4 months 24 days
Options exercisable at end of period, aggregate intrinsic value $ 27.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue
$7.21 to $9.71  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 7.21us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 9.71us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 216,105us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
Options outstanding, weighted average remaining contractual life (in years) 2 years 1 month 6 days
Options outstanding, weighted average exercise price (dollars per share) $ 8.88us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
Options exercisable 216,105us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
Options exercisable, weighted average exercise price (dollars per share) $ 8.88us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange1Member
$9.72 to $14.52  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 9.72us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 14.52us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 192,214us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
Options outstanding, weighted average remaining contractual life (in years) 3 years 6 months 0 days
Options outstanding, weighted average exercise price (dollars per share) $ 13.07us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
Options exercisable 192,214us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
Options exercisable, weighted average exercise price (dollars per share) $ 13.07us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange2Member
$14.53 to $19.93  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 14.53us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 19.93us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 15,516us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
Options outstanding, weighted average remaining contractual life (in years) 4 years 10 months 24 days
Options outstanding, weighted average exercise price (dollars per share) $ 17.21us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
Options exercisable 15,516us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
Options exercisable, weighted average exercise price (dollars per share) $ 17.21us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange3Member
$19.94 to $28.36  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 19.94us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 28.36us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 21,132us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
Options outstanding, weighted average remaining contractual life (in years) 5 years 9 months 18 days
Options outstanding, weighted average exercise price (dollars per share) $ 25.09us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
Options exercisable 21,132us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
Options exercisable, weighted average exercise price (dollars per share) $ 25.09us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange4Member
$28.37 to $70.38  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 28.37us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 58.45us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 46,266us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
Options outstanding, weighted average remaining contractual life (in years) 8 years 1 month 6 days
Options outstanding, weighted average exercise price (dollars per share) $ 49.29us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
Options exercisable 46,266us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
Options exercisable, weighted average exercise price (dollars per share) $ 49.29us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_Exercisepricerange5Member
$7.21 to $70.38  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit $ 7.21us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit $ 58.45us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Beginning of Period [Abstract]  
Options outstanding 491,233us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member
Options outstanding, weighted average remaining contractual life (in years) 3 years 4 months 24 days
Options outstanding, weighted average exercise price (dollars per share) $ 15.29us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member
Options exercisable 491,233us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member
Options exercisable, weighted average exercise price (dollars per share) $ 15.29us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= dltr_ExercisePriceRange6Member