Quarterly report pursuant to Section 13 or 15(d)

STOCK-BASED COMPENSATION (Narrative) (Details)

v2.4.1.9
STOCK-BASED COMPENSATION (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
May 02, 2015
May 03, 2014
Mar. 22, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 18.9us-gaap_ShareBasedCompensation $ 16.6us-gaap_ShareBasedCompensation  
Service Based Awards [Member] | Restricted Stock Units (RSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock granted under service and performance awards (in shares) 0.3dltr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsServiceAndPerformanceAwardsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= dltr_ServiceBasedAwardsMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Compensation Expense 4.7us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= dltr_ServiceBasedAwardsMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Fair Value 28.6dltr_ShareBasedCompensationTargetValue
/ us-gaap_AwardTypeAxis
= dltr_ServiceBasedAwardsMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Performance Shares [Member] | Omnibus Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Certain officers [Member] | Ratable Annual Vesting [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock granted under service and performance awards (in shares) 0.1dltr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsServiceAndPerformanceAwardsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_RatableAnnualVestingMember
   
Compensation Expense 6.8us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_RatableAnnualVestingMember
   
Fair Value 11.3dltr_ShareBasedCompensationTargetValue
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_RatableAnnualVestingMember
   
Performance And Service Based Awards [Member] | Omnibus Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Certain officers [Member] | Vesting at End of Performance Period [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation Expense 1.0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember
   
Fair Value 2.1dltr_ShareBasedCompensationTargetValue
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember
  1.4dltr_ShareBasedCompensationTargetValue
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember
Restricted Stock Units (RSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation Expense 6.1us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
5.6us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
Vested (shares) 0.7us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
0.7us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
Shares Issued in Period 0.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
0.5us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
2013 LTPP REGRANT [Member] | Performance And Service Based Awards [Member] | Omnibus Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Certain officers [Member] | Vesting at End of Performance Period [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation Expense 1.6us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_StatementEquityComponentsAxis
= dltr_A2013LTPPREGRANTMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember
   
Fair Value 2.2dltr_ShareBasedCompensationTargetValue
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_StatementEquityComponentsAxis
= dltr_A2013LTPPREGRANTMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember
   
2013 ORIGINAL LTPP GRANT [Member] | Performance And Service Based Awards [Member] | Omnibus Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Certain officers [Member] | Vesting at End of Performance Period [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation Expense $ 1.2us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= dltr_PerformanceAndServiceBasedAwardsMember
/ us-gaap_PlanNameAxis
= dltr_OmnibusIncentivePlanMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_StatementEquityComponentsAxis
= dltr_A2013ORIGINALLTPPGRANTMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
/ us-gaap_VestingAxis
= dltr_VestingAtEndOfPerformancePeriodMember