Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Narrative) (Details)

v2.4.1.9
Stock-Based Compensation (Narrative) (Details) (USD $)
3 Months Ended 6 Months Ended
Mar. 28, 2015
Mar. 29, 2014
Mar. 28, 2015
Mar. 29, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense $ 500,000us-gaap_AllocatedShareBasedCompensationExpense $ 200,000us-gaap_AllocatedShareBasedCompensationExpense $ 400,000us-gaap_AllocatedShareBasedCompensationExpense $ 400,000us-gaap_AllocatedShareBasedCompensationExpense
Exercises in period (shares) 0us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised   14,000us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised  
Performance Shares [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Grants during the period(shares)     169,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
 
Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Grants during the period(shares)     355,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
2010 Stock Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Aggregate number of shares that may be delivered (shares) 500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= dla_StockPlan2010Member
  500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= dla_StockPlan2010Member
 
Total compensation cost not yet recognized 4,400,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_PlanNameAxis
= dla_StockPlan2010Member
  4,400,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_PlanNameAxis
= dla_StockPlan2010Member
 
Period for recognition     3 years 8 months 12 days  
Option Plan [Member] | Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense     $ 0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= dla_OptionPlanMember
$ 0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= dla_OptionPlanMember