Debt Instrument, Covenant, Annual Coverage Ratio, Minimum

No definition available.

Name:	cog_DebtInstrumentCovenantAnnualCoverageRatioMinimum
Namespace Prefix:	cog_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Required asset coverage ratio

+ References

No definition available.

+ Details

Name:	cog_DebtInstrumentCovenantComplianceAssetCoverageRatio
Namespace Prefix:	cog_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Covenant Compliance, Number of Consecutive Fiscal Periods

+ References

No definition available.

+ Details

Name:	cog_DebtInstrumentCovenantComplianceNumberofConsecutiveFiscalPeriods
Namespace Prefix:	cog_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the ratio of current assets to current liabilities.

+ References

No definition available.

+ Details

Name:	cog_DebtInstrumentCovenantCurrentRatioMinimum
Namespace Prefix:	cog_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Number of Institutional Investors1

+ References

No definition available.

+ Details

Name:	cog_DebtInstrumentNumberofInstitutionalInvestors1
Namespace Prefix:	cog_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of tranches in which long-term debt is issued.

+ References

No definition available.

+ Details

Name:	cog_LongTermDebtNumberOfTranches
Namespace Prefix:	cog_
Data Type:	xbrli:integerItemType
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

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: 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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

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

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

+ Details

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

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_ExtinguishmentOfDebtAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingNonInvestmentGradeMember
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:	us-gaap_DebtInstrumentAxis=cog_ABRLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cog_LIBORLoansMember
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_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt and Credit Agreements - Narrative (Details)		1 Months Ended				12 Months Ended
Debt and Credit Agreements - Narrative (Details)	Apr. 22, 2019 USD ($)	May 31, 2016 USD ($)	Sep. 30, 2014 USD ($) Investor Tranche	Dec. 31, 2010 USD ($) Investor Tranche	Jul. 31, 2008 USD ($) Investor Tranche	Dec. 31, 2019 USD ($) fiscal_period	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Debt maturities, due in 2020						$ 87,000,000.0
Debt maturities, due in 2021						188,000,000.0
Debt maturities, due in 2023						62,000,000.0
Debt maturities, due in 2024						575,000,000.0
Repayments of debt						102,000,000	$ 455,000,000	$ 0
Deferred financing costs capitalized						3,975,000	4,896,000
Unamortized discount						$ 3,400,000
6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate						6.51%
Long-term debt						$ 124,000,000	124,000,000
5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate						5.58%
Long-term debt						$ 175,000,000	175,000,000
3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate						3.65%
Long-term debt						$ 925,000,000	$ 925,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Minimum required asset coverage ratio						1.75
Fiscal quarters for reduction in coverage ratio \| fiscal_period						4
Minimum required annual coverage ratio						2.8
Maximum borrowing capacity on line of credit	$ 3,200,000,000
Remaining borrowing capacity on line of credit	$ 1,500,000,000					$ 1,500,000,000
Minimum current ratio						1.0
Long-term debt						$ 0
Interest rate							6.30%
Senior Notes
Debt Instrument [Line Items]
Minimum required asset coverage ratio						1.75
Fiscal quarters for reduction in coverage ratio \| fiscal_period						4
Minimum required annual coverage ratio						2.8
Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 425,000,000.0
Number of institutional investors \| Investor					41
Number of debt tranches \| Tranche					3
Repayments of debt						$ 301,000,000.0
Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 175,000,000.0
Number of institutional investors \| Investor				8
Number of debt tranches \| Tranche				3
Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal			$ 925,000,000.0
Number of institutional investors \| Investor			24
Number of debt tranches \| Tranche			3
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt						0	$ 7,000,000.0
Deferred financing costs capitalized						$ 7,400,000
Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased		$ 64,000,000.0
Repayments of debt		68,300,000
Tranche 1 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 245,000,000
Tranche 1 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 88,000,000
Tranche 1 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal			$ 100,000,000
Tranche 1 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased		8,000,000.0
Tranche 2 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					100,000,000
Tranche 2 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				25,000,000
Tranche 2 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal			575,000,000
Tranche 2 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased		13,000,000.0
Tranche 3 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 80,000,000
Tranche 3 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 62,000,000
Tranche 3 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal			$ 250,000,000
Tranche 3 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased		$ 43,000,000.0
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	0.30%
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	0.425%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	0.125%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	0.125%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.125%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	0.275%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%