Annual report pursuant to Section 13 and 15(d)

SHAREHOLDERS' EQUITY (Narrative) (Details)

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SHAREHOLDERS' EQUITY (Narrative) (Details) (USD $)
 3 Months Ended 12 Months Ended 1 Months Ended 4 Months Ended
May 15, 2014
Jan. 31, 2015
Feb. 01, 2014
Feb. 02, 2013
Dec. 13, 2011
Mar. 28, 2012
Feb. 14, 2014
Nov. 21, 2011
Accelerated Share Repurchases [Line Items]                
Total Shares Delivered Under Conclusion of Collared ASR Agreement 9,000,000dltr_TotalSharesDeliveredUnderConclusionofCollaredASRAgreement              
Number of accelerated share repurchase programs entered into     2dltr_Numberofacceleratedsharerepurchaseprogramsenteredinto          
Amount of each accelerated share repurchase agreement     $ 500,000,000.0dltr_Amountofeachacceleratedsharerepurchaseagreement          
Accelerated Share Repurchase Program Authorized Amount     1,000,000,000.0dltr_AcceleratedShareRepurchaseProgramAuthorizedAmount          
Shares delivered under the conclusion of the Uncollared Agreement             1,900,000dltr_SharesdeliveredundertheconclusionoftheUncollaredAgreement  
Total shares delivered under Uncollared Repurchase Agreement   9,100,000dltr_TotalsharesdeliveredunderUncollaredRepurchaseAgreement            
Preferred Stock                
Preferred Stock authorized to issue (in shares)   10,000,000us-gaap_PreferredStockSharesAuthorized            
Preferred Stock par value per share   $ 0.01us-gaap_PreferredStockParOrStatedValuePerShare            
Share Repurchase Programs                
Number of shares repurchased (in shares)     2,400,000dltr_StockRepurchaseProgramStockRepurchasedAndRetiredDuringPeriodShares 7,700,000dltr_StockRepurchaseProgramStockRepurchasedAndRetiredDuringPeriodShares        
Amount of shares repurchased     112,100,000dltr_StockRepurchaseProgramStockRepurchasedAndRetiredDuringPeriodValue 340,200,000dltr_StockRepurchaseProgramStockRepurchasedAndRetiredDuringPeriodValue        
Remaining amount of shares authorized to repurchase   1,000,000,000dltr_DollarAmountOfSharesCommonStockAuthorizedToRepurchase            
Accelerated Share Repurchases                
Minimum Number Of Shares To Be Received Under Collar Agreement     7,800,000dltr_MinimumNumberOfSharesToBeReceivedUnderCollarAgreement          
Shares Received at Conclusion Collared ASR Agreement 1,200,000dltr_SharesReceivedatConclusionCollaredASRAgreement              
Initial delivery of shares under the Uncollared Agreement     7,200,000dltr_InitialdeliveryofsharesundertheUncollaredAgreement          
Accelerated Share Repurchase Agreement November 2011 [Member]                
Accelerated Share Repurchases                
Accelerated Share Repurchases Amount to Repurchase               $ 300,000,000.0dltr_AcceleratedShareRepurchasesAmountToRepurchase
/ us-gaap_AcceleratedShareRepurchasesDateAxis
= dltr_AcceleratedShareRepurchaseAgreementNovember2011Member
Initial number of shares repurchased (in shares)         6,800,000dltr_AcceleratedShareRepurchaseAgreementInitialNumberOfSharesRepurchased
/ us-gaap_AcceleratedShareRepurchasesDateAxis
= dltr_AcceleratedShareRepurchaseAgreementNovember2011Member 		     
Additional number of shares of common stock repurchased (in shares)           500,000dltr_AcceleratedShareRepurchaseAgreementAdditionaLnumberOfSharesRepurchased
/ us-gaap_AcceleratedShareRepurchasesDateAxis
= dltr_AcceleratedShareRepurchaseAgreementNovember2011Member 		   
Total shares of common stock repurchased (in shares)           7,300,000dltr_AcceleratedShareRepurchaseAgreementTotalNumberOfSharesRepurchased
/ us-gaap_AcceleratedShareRepurchasesDateAxis
= dltr_AcceleratedShareRepurchaseAgreementNovember2011Member