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Operating and finance lease liability.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiability
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDue
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due after year five.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDueAfterYearFive
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due year five.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDueYearFive
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due year four.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDueYearFour
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due year three.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDueYearThree
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments due year two.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsDueYearTwo
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating and finance lease liability payments remainder of fiscal year.

No definition available.

Name:	nsit_OperatingAndFinanceLeaseLiabilityPaymentsRemainderOfFiscalYear
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount necessary to reduce minimum lease payments to present value for operating and finance leases.

No definition available.

Name:	nsit_OperatingAndFinanceLeasesFutureMinimumPaymentsInterestIncludedInPayments
Namespace Prefix:	nsit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Operating Lease.

No definition available.

Name:	nsit_OperatingLeaseAbstract
Namespace Prefix:	nsit_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Present value of lessee's discounted obligation for lease payments from finance lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

Name:	us-gaap_FinanceLeaseLiability
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of lessee's undiscounted obligation for lease payments for finance lease.

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

Amount of lessee's undiscounted obligation for lease payments for finance lease, due in fifth fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for finance lease, due in fourth fiscal year following latest fiscal year.

Name:	us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of lessee's undiscounted obligation for lease payments for finance lease, due in third fiscal year following latest fiscal year.

Name:	us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of lessee's undiscounted obligation for lease payments for finance lease, due in second fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for finance lease, due in remainder of fiscal year following latest fiscal year ended.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

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

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for finance lease.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fifth fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fifth fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fourth fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in third fiscal year following latest fiscal year.

Name:	us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in second fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments for operating lease having an initial or remaining lease term in excess of one year due in remainder of fiscal year following latest fiscal year.

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

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

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

Present value of lessee's discounted obligation for lease payments from operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977