Debt Instrument, Discount Coverage Ratio

No definition available.

Name:	swn_DebtInstrumentDiscountCoverageRatio
Namespace Prefix:	swn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Total debt divided by EBITDAX.

+ References

No definition available.

+ Details

Name:	swn_LeverageRatio
Namespace Prefix:	swn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Leverage Ratio, Amount of Credit Limit

+ References

No definition available.

+ Details

Name:	swn_LeverageRatioAmountOfCreditLimit
Namespace Prefix:	swn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Leverage Ratio, Percentage of Credit Limit

+ References

No definition available.

+ Details

Name:	swn_LeverageRatioPercentageOfCreditLimit
Namespace Prefix:	swn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Long-Term Debt, Excluding Maturities, Gross

+ References

No definition available.

+ Details

Name:	swn_LongTermDebtExcludingMaturitiesGross
Namespace Prefix:	swn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Minimum Current Ratio

+ References

No definition available.

+ Details

Name:	swn_MinimumCurrentRatio
Namespace Prefix:	swn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

EBITDAX divided by consolidated interest expense.

+ References

No definition available.

+ Details

Name:	swn_MinimumInterestCoverageRatio
Namespace Prefix:	swn_
Data Type:	xbrli:pureItemType
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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- 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

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: 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 https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 3: 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 https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

+ Details

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

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Name:	us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsidiaryOrEquityMethodInvesteeCumulativePercentageOwnershipAfterAllTransactions
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=swn_A2022RevolvingCreditFacilityMember
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_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	swn_DebtInstrumentCovenantCompliancePeriodOfComplianceAxis=swn_OnOrAfterMarch312022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=swn_A2022RevolvingCreditFacilityFiveYearTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=swn_A2022RevolvingCreditFacilityShortTermTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (2022 Credit Facility - Narrative) (Details)				9 Months Ended
Debt (2022 Credit Facility - Narrative) (Details)	Aug. 04, 2022 USD ($)	Apr. 08, 2022 USD ($)	Dec. 22, 2021	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Subsidiary ownership				100.00%
Long-term debt
Debt Instrument [Line Items]
Debt instrument, excluding current maturities, gross				$ 4,885,000,000	$ 5,234,000,000
2022 Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage		0.375%	0.15%
2022 Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage	0.50%	0.50%	0.275%
Ratio of indebtedness to net capital			0.65
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity				3,500,000,000
Aggregate commitment				3,500,000,000
Line of credit facility, increase, net	$ 500,000,000
Minimum current ratio		1.00
Leverage ratio, percentage of credit limit		10.00%
Leverage ratio, amount of credit limit		$ 150,000,000
Letters of credit				109,000,000
Debt instrument, excluding current maturities, gross				$ 180,000,000	$ 460,000,000
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| On Or After March 31, 2022
Debt Instrument [Line Items]
Leverage ratio		4.00
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis points		0.10%	0.10%
Debt instrument, discount coverage ratio			9.00%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Base Rate
Debt Instrument [Line Items]
Basis points		1.00%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Fed Funds Effective Rate Overnight Index Swap Rate
Debt Instrument [Line Items]
Basis points		0.50%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Minimum \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis points	2.75%	1.75%	1.25%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Minimum \| Base Rate
Debt Instrument [Line Items]
Basis points	1.75%	0.75%	0.25%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Maximum \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis points	0.10%	2.75%	1.875%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Line of Credit \| Maximum \| Base Rate
Debt Instrument [Line Items]
Basis points		1.75%	0.875%
Revolving Credit Facility \| 2022 Revolving Credit Facility \| Long-term debt
Debt Instrument [Line Items]
Minimum interest coverage ratio			1.50
Revolving Credit Facility \| 2022 Revolving Credit Facility Five-Year Tranche \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility, expiration period				5 years
Aggregate commitment				$ 2,000,000,000
Revolving Credit Facility \| 2022 Revolving Credit Facility Short-Term Tranche \| Line of Credit
Debt Instrument [Line Items]
Aggregate commitment				$ 500,000,000