The amount of increase (decrease) net working capital adjustments in a business combination.

No definition available.

Name:	dsgx_BusinessCombinationIncreaseDecreaseInNetWorkingCapitalAdjustments
Namespace Prefix:	dsgx_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of net working capital adjustments in a business combination.

+ References

No definition available.

+ Details

Name:	dsgx_BusinessCombinationNetWorkingCapitalAdjustments
Namespace Prefix:	dsgx_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to income taxes payable and goodwill in connection with a business combination for which the initial accounting was incomplete.

+ References

No definition available.

+ Details

Name:	dsgx_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIncomeTaxesPayableAndGoodwill
Namespace Prefix:	dsgx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	dsgx_Note3AcquisitionsDetailsLineItems
Namespace Prefix:	dsgx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

Name:	us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of shares of equity interests issued or issuable to acquire entity.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the contractual cash flows not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the fair value of the receivables acquired, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

+ Details

Name:	us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of increase (decrease) of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_OzMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_BearWareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_MKDataMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_TwoThousandSixteenAcquisitionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=dsgx_OtherChargesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_PentantLimitedPentantMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_EcustomsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_AirclicMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_CustomsInfoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=dsgx_DrawOnRevolvingDebtFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_ComputerManagementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_TwoThousandFifteenAcquisitionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_ImpatexMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_CompudataMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_KSDMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dsgx_TwoThousandFourteenAcquisitionsMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=dsgx_DecreaseFromMember
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Balance Type:
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Period Type:

Note 3 - Acquisitions (Details) shares in Thousands, £ in Millions									1 Months Ended		3 Months Ended	12 Months Ended
	Nov. 25, 2015 USD ($)	Jul. 22, 2015 USD ($)	Jul. 20, 2015 USD ($)	Dec. 05, 2014 USD ($)	Nov. 19, 2014 USD ($)	May. 30, 2014 USD ($) shares	Apr. 01, 2014 USD ($)	May. 02, 2013 USD ($)	Dec. 23, 2013 USD ($)	Dec. 20, 2013 USD ($)	Oct. 31, 2015 USD ($)	Jan. 31, 2016 USD ($)	Jan. 31, 2015 USD ($) shares	Jan. 31, 2014 USD ($)	Jan. 31, 2015 GBP (£)
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Acquisition Related Costs												$ 1,416,000	$ 1,666,000	$ 1,308,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares) \| shares													416
Goodwill												217,486,000	$ 147,440,000	111,179,000
Oz [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred	$ 29,500,000											29,398,000
Business Combination, Acquired Receivables, Gross Contractual Amount	300,000
Business Combination, Acquired Receivables, Fair Value	$ 300,000
Goodwill												17,637,000
BearWare [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred		$ 11,200,000										11,224,000
Business Combination, Acquired Receivables, Gross Contractual Amount		800,000
Business Combination, Acquired Receivables, Fair Value		700,000
Business Combination, Acquired Receivables, Estimated Uncollectible		$ 100,000
Goodwill												4,958,000
MK Data [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred			$ 80,200,000									80,018,000
Business Combination, Acquired Receivables, Gross Contractual Amount			1,300,000
Business Combination, Acquired Receivables, Fair Value			1,200,000
Business Combination, Acquired Receivables, Estimated Uncollectible			100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 3,100,000
Goodwill												51,108,000
2016 Acquisitions [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred												120,640,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual												2,400,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual												7,700,000
Goodwill												73,703,000
2016 Acquisitions [Member] \| Other Charges [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Acquisition Related Costs												1,200,000
Pentant Limited (Pentant) [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred				$ 2,100,000
Business Combination, Acquired Receivables, Gross Contractual Amount				100,000
Business Combination, Acquired Receivables, Fair Value				100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High													400,000		£ 0.3
Business Combination, Contingent Consideration, Liability				400,000								$ 0
e-customs [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred				9,600,000									9,570,000
Business Combination, Acquired Receivables, Gross Contractual Amount				200,000
Business Combination, Acquired Receivables, Fair Value				200,000
Business Combination, Contingent Consideration, Liability				$ 1,200,000
Goodwill													4,581,000
Airclic [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred					$ 29,600,000								29,279,000
Business Combination, Acquired Receivables, Gross Contractual Amount					4,500,000
Business Combination, Acquired Receivables, Fair Value					$ 4,500,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Income Taxes Payable and Goodwill											$ 800,000
Goodwill													12,480,000
Customs Info [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred						$ 39,500,000							38,690,000
Business Combination, Acquired Receivables, Gross Contractual Amount						1,800,000
Business Combination, Acquired Receivables, Fair Value						1,700,000
Business Combination, Acquired Receivables, Estimated Uncollectible						100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High						3,900,000
Payments to Acquire Businesses, Gross						$ 34,100,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares) \| shares						400
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned						$ 5,400,000
Goodwill													26,135,000
Customs Info [Member] \| Draw on Revolving Debt Facility [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred						$ 20,000,000
Computer Management [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred							$ 6,700,000						6,692,000
Business Combination, Acquired Receivables, Gross Contractual Amount							200,000
Business Combination, Acquired Receivables, Fair Value							$ 200,000
Goodwill													1,338,000
2015 Acquisitions [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred													86,352,000
Goodwill													45,593,000
2015 Acquisitions [Member] \| Other Charges [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Acquisition Related Costs													1,500,000
Impatex [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred									$ 8,200,000					7,966,000
Business Combination, Acquired Receivables, Gross Contractual Amount									300,000
Business Combination, Acquired Receivables, Fair Value									300,000
Business Combination, Acquisition Related Costs									$ 300,000
Goodwill														3,501,000
Compudata [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred										$ 18,100,000				18,072,000
Business Combination, Acquired Receivables, Gross Contractual Amount										600,000
Business Combination, Acquired Receivables, Fair Value										500,000
Business Combination, Acquired Receivables, Estimated Uncollectible										100,000
Business Combination, Acquisition Related Costs										$ 300,000
Goodwill														8,201,000
KSD [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred								$ 32,400,000						30,206,000
Business Combination, Acquired Receivables, Gross Contractual Amount								3,100,000
Business Combination, Acquired Receivables, Fair Value								2,600,000
Business Combination, Acquired Receivables, Estimated Uncollectible								500,000
Business Combination, Acquisition Related Costs								700,000
Goodwill, Period Increase (Decrease)													700,000
Goodwill														13,824,000
Business Combination, Increase (Decrease) in Net Working Capital Adjustments													700,000
KSD [Member] \| Draw on Revolving Debt Facility [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred								$ 19,800,000
2014 Acquisitions [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Consideration Transferred														56,244,000
Goodwill														25,526,000
2014 Acquisitions [Member] \| Other Charges [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Acquisition Related Costs														$ 1,400,000
Increase From [Member] \| KSD [Member]
Note 3 - Acquisitions (Details) [Line Items]
Goodwill													13,100,000
Increase To [Member] \| KSD [Member]
Note 3 - Acquisitions (Details) [Line Items]
Goodwill													13,800,000
Decrease From [Member] \| KSD [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Net Working Capital Adjustments													2,900,000
Decrease To [Member] \| KSD [Member]
Note 3 - Acquisitions (Details) [Line Items]
Business Combination, Net Working Capital Adjustments													$ 2,200,000