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Note 18 - Deferred Tax Charge (Details) | 12 Months Ended
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Jan. 31, 2016
Minimum [Member] |
Note 18 - Deferred Tax Charge (Details) [Line Items] |
Amortization Period of Deferred Tax Charge | 3 years
Maximum [Member] |
Note 18 - Deferred Tax Charge (Details) [Line Items] |
Amortization Period of Deferred Tax Charge | 8 years

X
- Definition Represents the period of amortization to income tax expense of a deferred tax charge. + References No definition available. + Details
Name: | dsgx_AmortizationPeriodOfDeferredTaxCharge
Namespace Prefix: | dsgx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | dsgx_Note18DeferredTaxChargeDetailsLineItems
Namespace Prefix: | dsgx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |