Line of Credit Facility, Interest Period

No definition available.

Name:	ctsh_LineOfCreditFacilityInterestPeriod
Namespace Prefix:	ctsh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ctsh_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_EurodollarMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=ctsh_EurocurrencyWithoutDebtRatingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ctsh_WorkingCapitalFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Additional Disclosures) (Details) $ in Millions, ₨ in Billions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 INR (₨)	Nov. 30, 2018 USD ($)
Credit Agreement [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Period	1 month
Credit Agreement [Member] \| Term Loan [Member]
Line of Credit Facility [Line Items]
Principal amount of debt					$ 750
Eurodollar [Member] \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.875%
Eurodollar [Member] \| Minimum \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.75%
Eurodollar [Member] \| Maximum \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.125%
Base Rate [Member] \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.00%
Eurocurrency Without Debt Ratings [Member] \| Minimum \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.875%
Eurocurrency Without Debt Ratings [Member] \| Maximum \| Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.125%
Revolving Credit Facility [Member] \| Credit Agreement [Member] \| Unsecured Debt [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 1,750
Proceeds from Lines of Credit		$ 1,740
Working Capital Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 172		$ 172	₨ 13