Portion at Fair Value, Fair Value Disclosure Portion at Fair Value Measurement [Member] Acquisition-related costs as of the beginning of the earliest period presented Business Combination, Acquisition Costs Included in Earnings as of the Beginning of the Earliest Period Presented Amount of acquisition-related costs that were recognized in earnings prior to the earliest period presented and therefore are reflected in the pro forma financial information adjustment disclosures. Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Carrying Amount Reported Value Measurement [Member] Document Fiscal Year Focus Document Fiscal Year Focus Remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Acquisition-related costs Business Combination, Acquisition-Related Cost, Expense Weighted-average interest rates Debt, Weighted Average Interest Rate Segment Reporting [Abstract] Accrued payroll and employee benefits Employee-related Liabilities, Current Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Employee Benefits Retirement Benefits [Text Block] Line of Credit Line of Credit [Member] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Other operating revenues Revenue Not From Contract With Customer, Including Certain NGL Amounts Certain revenues earned from operating leases, pipeline management fees, intrasegment licensing fees and other activities that are not considered central and ongoing major business operations of the Company and do not represent revenues earned from contracts with customers. Derivative Instrument [Axis] Derivative Instrument [Axis] Loss (gain) on sale of assets, impairments and other Loss (gain) on sale of assets, impairments and other Gain (Loss) On Sale Of Assets, Asset Impairment Charges And Other Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold, impairment charges from the write down of assets from their carrying value to fair value and other. Measurement Frequency [Axis] Measurement Frequency [Axis] Proceeds from sale of operating assets Proceeds from Sale of Productive Assets Amendment Flag Amendment Flag Consolidated Entities [Axis] Consolidated Entities [Axis] Current Liabilities: Liabilities, Current [Abstract] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Principal payment of finance lease obligation Finance Lease, Principal Payments Thereafter Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Four Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Four Loss Contingencies [Table] Loss Contingencies [Table] Leases [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Consolidated Entities [Domain] Consolidated Entities [Domain] Related Party Transactions Related Party Transactions Disclosure [Text Block] Other Accounts Payable, Other, Current Property, Plant and Equipment: Property, Plant, and Equipment [Abstract] Entity Address, State Entity Address, State or Province Capital expenditures Segment Reporting, Long-Lived Asset, Expenditure for Addition Provision for other asset retirement Provision for other asset retirement Noncurrent portion of the estimated cost of removal collected in rates for operations where ASC 980 is applicable. These removal liabilities do not represent an existing legal obligation. Other Liabilities and Deferred Credits: Liabilities, Noncurrent [Abstract] Purchase commitments, expected to be settled through the end of 2028 Short-Term and Long-Term Purchase Commitments, Amount The minimum amount the entity agreed to spend under the short-term and long-term purchase commitments. Retirement Benefits [Abstract] Retirement Benefits [Abstract] Fair Value, by Balance Sheet Grouping [Table] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value, by Balance Sheet Grouping [Table] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Short-term investments, carrying amount Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss Number of reportable segments Number of Reportable Segments Total current liabilities Liabilities, Current Taxes other than income taxes Taxes, Miscellaneous Derivative liability, current Derivative Liability, Current Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Entity Address, City Entity Address, City or Town Supplemental Disclosure of Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Level 2 Fair Value, Inputs, Level 2 [Member] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Current portion of long-term debt Long-Term Debt, Current Maturities Parent Company Parent Company [Member] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Accounts payable and property, plant and equipment Capital Expenditures Incurred but Not yet Paid Litigation Case [Axis] Litigation Case [Axis] Increases due to cash received, excluding amounts recognized as revenues during the period Increase (Decrease) in Contract with Customer, Liability Segment Reporting Segment Reporting [Table Text Block] Partners' Capital General Partner And Limited Partner [Member] Parties who together hold 100% interest in the partnership – General Partner interest 51%; Limited Partner interest 49% Unsecured Debt Unsecured Debt [Member] Related Party, Type [Axis] Related and Nonrelated Parties [Axis] Natural Gas Liquids Reportable Segment Natural Gas Liquids Reportable Segment [Member] Natural Gas Liquids Reportable Segment Document Period End Date Document Period End Date Changes in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Effect of netting and cash margin receivables/payables, liability Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset Supplemental Disclosure of Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] 2028 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two Liabilities, fair value, recurring Liabilities, Fair Value Disclosure Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Contract assets from contracts with customers Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent Natural Gas Reportable Segment Natural Gas Reportable Segment [Member] Natural Gas Reportable Segment Accrued interest Interest Payable, Current Boardwalk Pipelines 5.95% Notes Due 2026 Boardwalk Pipelines 5.95% Notes Due 2026 [Member] Boardwalk Pipelines 5.95% Notes Due 2026 Business Combination, Pro Forma Information [Line Items] Business Combination, Pro Forma Information [Line Items] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Partner Type [Axis] Partner Type [Axis] Capital expenditures Payments to Acquire Property, Plant, and Equipment Retirement Plans Pension And SRP Plans [Member] Pension And SRP Plans Final Fair Values of the Assets Acquired and Liabilities Assumed Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] 2029 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three Interruptible Service Interruptible Service Contracts [Member] Interruptible Service Contracts: Contracts that agree to transport natural gas or natural gas liquids for a customer when capacity is available. Net unrealized loss on derivative instruments Unrealized Gain (Loss) on Derivatives Natural gas liquids balancing measurement (in MMBbls) (less than) Natural Gas Liquids Balancing Volume The amount of natural gas liquids imbalance in terms of measure (MMbbls) as of the end of the period. Ownership percentage Subsidiary, Ownership Percentage, Parent Total notes and debentures Long-Term Debt, Gross Gas receivables and payables and product inventory Increase (Decrease) In Gas Receivables And Payable And Product Inventory Increase (Decrease) In Gas Receivables And Payable And Product Inventory Firm Service Firm Service Contracts [Member] Firm Service Contracts: Firm service that allows customers the ability to reserve a specific amount of pipeline capacity at specified receipt and delivery points on the Company's system (transportation service) or customers can reserve a specific amount of storage capacity at specified injection and withdrawal points at the Company’s storage facilities (storage service) . Natural gas basis swaps Natural gas basis swaps [Member] Natural gas basis swaps Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Related Party Transactions [Abstract] Related Party Transactions [Abstract] Operating Activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Percentage of voting interests acquired Business Combination, Voting Equity Interest Acquired, Percentage Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Related Party Transaction [Line Items] Related Party Transaction [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Derivative Instruments Derivatives, Policy [Policy Text Block] Property, plant and equipment, net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Entities [Table] Entities [Table] Gas Balancing Arrangements [Abstract] Oil and Gas, Gas-Balancing Arrangement [Abstract] Contribution to defined benefit pension plan Defined Benefit Plan, Plan Assets, Contributions by Employer Regulatory asset decrease (Increase) Decrease in Regulatory Asset The (reduction to expense) expense charged against earnings during the period to meet the previously settled rate case pension cost regulatory requirement. Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Less—accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Add (deduct): Adjustments to Additional Paid in Capital [Abstract] Boardwalk Pipelines, LP Boardwalk Pipelines, LP [Member] Boardwalk Pipelines, LP Outstanding Letters of Credit Letters of Credit Outstanding, Amount Repayment of borrowings from long-term debt Repayment of borrowings from long-term debt Repayments of Unsecured Debt Level 1 Fair Value, Inputs, Level 1 [Member] Derivative asset, noncurrent Derivative Asset, Noncurrent Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Litigation Status [Domain] Litigation Status [Domain] Derivative asset Derivative Asset, Gross Asset Including Not Subject to Master Netting Arrangement Product sales Product Sales Revenue Product sales revenue related to the sales of natural gas or NGLs to customers. Partner Capital Components [Domain] Partner Capital Components [Domain] Repayments of borrowings on revolving credit facility, including financing fees Repayments of Long-Term Lines of Credit Operating revenues which are fixed and determinable (operating leases) Operating Leases, Future Minimum Lease Revenues The total amount of future minimum lease revenues to be recognized in future periods under leasing arrangements for which the lessee is obligated. Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Operating lease, right-of-use asset Operating Lease, Right-of-Use Asset Net assets acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Natural gas futures Natural gas futures [Member] Natural gas futures Reportable Segments Segment Reporting [Text Block] Line of credit, outstanding borrowings Long-Term Line of Credit Short-term debt refinanced Short-Term Debt, Refinanced, Amount Distributions paid Cash dividends paid to parent company Payments of Ordinary Dividends, Common Stock Derivative liability Derivative Liability, Gross Liability Including Not Subject to Master Netting Arrangement Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Other Nonrelated Party [Member] Net periodic benefit cost (credit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Trade receivables Business Combination, Recognized Asset Acquired, Receivable, Current Trade and other receivables Increase (Decrease) in Accounts and Other Receivables Investing Activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Litigation Status [Axis] Litigation Status [Axis] Fair Value, Recurring Fair Value, Recurring [Member] Segment Reporting [Line Items] Segment Reporting [Line Items] Other Nontrade Receivables, Current Net income Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax Document Quarterly Report Document Quarterly Report Derivative Asset [Abstract] Derivative Asset [Abstract] Segments [Domain] Segments [Domain] Financing Debt Disclosure [Text Block] Derivative Liability [Abstract] Derivative Liability [Abstract] Interest income from short-term investments Interest Income, Short-Term Investment, Increase (Decrease) Business Combination [Table] Business Combination [Table] Natural gas options Natural gas options [Member] Natural gas options Line of Credit Facility [Abstract] Line of Credit Facility [Abstract] Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Trade Accounts Payable, Trade, Current Debt interest rate Debt Instrument, Interest Rate, Stated Percentage Total other deductions Nonoperating Income (Expense) Entity Addresses, Address Type [Axis] Entity Addresses, Address Type [Axis] Settlement charge Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Other Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent Other Other Revenue Operating revenue other than transportation, storage, parking and lending, and product sales. ASSETS Assets [Abstract] Gas balancing measurement (in TBtu) Gas Balancing Measurement The amount of gas imbalance in terms of measure (MMBtu) as of the end of the period. Operating lease, liability Operating Lease, Liability Advances from affiliates Proceeds from (Payment for) Other Financing Activity Ethylene loaned balance due to operating subsidiaries (asset) Imbalance of Ethylene Asset Liability Imbalance of Ethylene Asset Liability Contract With Customer, Liability [Roll Forward] Contract With Customer, Liability [Roll Forward] Contract With Customer, Liability Business Combination, Acquiree [Domain] Business Combination [Domain] Letter of Credit Letter of Credit [Member] Gas stored underground Inventory, Gas in Storage Underground, Noncurrent Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Number of operating segments Number of Operating Segments Segment EBITDA Segment EBITDA Segment earnings before interest, tax, depreciation and amortization (EBITDA). Entity Central Index Key Entity Central Index Key Other Miscellaneous Other Assets, Noncurrent Amount of other noncurrent assets not separately identified on the face of the balance sheet. Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Business Combination [Axis] Business Combination [Axis] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Gas imbalance to subsidiaries asset liability Imbalance Of Gas Asset Liability The value of gas balancing asset or liability as of the end of the period Boardwalk Pipeline Partners, LP Boardwalk Pipeline Partners, LP [Member] Boardwalk Pipeline Partners, LP Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition Report Ownership [Axis] Ownership [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Long-term finance lease obligation Finance Lease, Liability, Noncurrent Other current assets Business Combination, Recognized Asset Acquired, Other Asset, Current City Area Code City Area Code Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Property, plant and equipment, gross Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization Debt, current and long-term Debt Instrument, Fair Value Disclosure Distributions paid Partners' Capital Account, Distributions Statement [Line Items] Statement [Line Items] Receivables from contracts with customers Contract with Customer, Receivable, after Allowance for Credit Loss, Current Total Assets Total Assets Assets Notional (MMBtu millions) Derivative, Nonmonetary Notional Amount, Energy Measure Entity [Domain} Entity [Domain] Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Operating Segments Operating Segments [Member] Partner Capital Components [Axis] Partner Capital Components [Axis] Interest expense Interest Expense, Nonoperating Total partners' capital Beginning balance Ending balance Partners' Capital Total liabilities assumed Business Combination, Recognized Liability Assumed, Liability Energy [Domain] Energy [Domain] Prepayments and other assets Increase (Decrease) in Other Operating Assets Accrued taxes, other Accrual for Taxes Other than Income Taxes, Current Measurement Basis [Axis] Measurement Basis [Axis] Other Other Liabilities, Noncurrent Goodwill Goodwill Retirement Plan Type [Axis] Retirement Plan Type [Axis] Goodwill Goodwill, Acquired During Period Trade payables and other current liabilities Business Combination, Recognized Liability Assumed, Accounts Payable, Current Revenues recognized that were included in the contract liability balances at the beginning of the period Contract with Customer, Liability, Revenue Recognized Total operating costs and expenses Operating Expenses Operating lease, impairment charge Operating Lease, Impairment Loss Disaggregation of Revenue [Abstract] Disaggregation of Revenue [Abstract] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Entity Current Reporting Status Entity Current Reporting Status Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Litigation Case [Domain] Litigation Case [Domain] Ownership [Domain] Ownership [Domain] Pro Forma Information Business Combination, Pro Forma Information [Table Text Block] Proceeds from borrowings on revolving credit facility Proceeds from Long-Term Lines of Credit Operation and maintenance Utilities Operating Expense, Maintenance and Operations Adjustments to reconcile net income to cash provided by operations: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Total assets acquired Business Combination, Recognized Asset Acquired, Asset Pipeline and Storage Capacity Agreements [Line Items] Long-Term Purchase Commitment [Line Items] Revenues from Contracts with Customers Revenue from Contract with Customer, Excluding Assessed Tax Financing Activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Boardwalk GP, LP Boardwalk Gp, Lp [Member] Boardwalk Gp, Lp Available borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Interest cost Defined Benefit Plan, Interest Cost Assets held for sale Disposal Group, Including Discontinued Operation, Assets, Current Financial Assets Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Derivative asset, total Derivative Asset Estimated Fair Value Estimate of Fair Value Measurement [Member] Revenues Revenue from Contract with Customer [Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Prepayments Prepaid Expense, Current Capacity and Storage Agreements Capacity and Storage Agreements [Member] Capacity and Storage Agreements Business Combination, Pro Forma Information [Table] Business Combination, Pro Forma Information [Table] Ethylene loaned volume (in pounds) Ethylene Loaned Volume The amount of ethylene loaned due to operating subsidiaries in terms of measure (pounds) as of the end of the period. Advances to affiliates Payment for (Proceeds from) Other Investing Activity Construction work in progress Construction in Progress [Member] Address Type [Domain] Address Type [Domain] Segment Reporting [Table] Segment Reporting [Table] Expected future contributions Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Natural gas liquids imbalance to subsidiaries of asset liability Imbalance of Natural Gas Liquids Asset Liability Imbalance of Natural Gas Liquids Asset Liability Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Acquisition, operating revenue contribution Business Combination, Acquiree's Revenue since Acquisition Date, Actual Other current assets Other Assets, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Derivative gain (loss) recorded in income Derivative, Gain (Loss) on Derivative, Net Operating income Operating Income (Loss) Cash paid during the period for: Interest Paid, Including Capitalized Interest, Operating and Investing Activities [Abstract] Average market price of gas assumed (in dollars per MMBTU) Average Market Price Of Gas Assumed Average market price of natural gas assumed during the month prior to the balance sheet date and used to calculate the total market value of (1) gas held in storage on behalf of customers, and (2) gas owed to operating subsidiaries due to gas imbalances and gas loaned under parking and lending agreements. Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2026 Revenue, Remaining Performance Obligation, Amount Current Fiscal Year End Date Current Fiscal Year End Date Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Short-term investments, fair value Debt Securities, Held-to-Maturity, Fair Value, Current Acquisition and Divestiture Business Combination [Text Block] Total Unrecorded Unconditional Purchase Obligation Entity File Number Entity File Number Service cost Defined Benefit Plan, Service Cost Entity Information [Line Items] Entity Information [Line Items] Fixed fee revenues recognized Fixed Fee Revenues Recognized Fixed fee revenues recognized during the period that were included in projected operating revenues under committed firm agreements. Increase (Decrease) in Partners' Capital [Roll Forward] Increase (Decrease) in Partners' Capital [Roll Forward] Forward natural gas contracts Forward Contracts [Member] Asset retirement obligations Asset Retirement Obligations, Noncurrent Derivative assets - current Business Combination, Recognized Asset Acquired, Asset, Current Product and Service [Domain] Product and Service [Domain] Affiliates Related Party [Member] Transportation Transportation Revenue Revenue related to providing transportation services to natural gas and natural gas liquids customers Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Entity Interactive Data Current Entity Interactive Data Current Acquisition, net loss contribution Business Combination, Acquiree's Earnings (Loss) since Acquisition Date, Actual Defined contribution plan, cost Defined Contribution Plan, Cost Entity Small Business Entity Small Business Total Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Noncontrolling Interest [Table] Noncontrolling Interest [Table] Pre-judgment interest awarded to other party (approximately) Litigation Settlement, Pre-Judgment Interest, Amount Awarded to Other Party Pre-judgment interest amount awarded to other party in judgment or settlement of litigation. Pension and other postretirement benefit costs, net of tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Other current liabilities Other Liabilities, Current Total other assets Other Assets, Noncurrent Document Type Document Type Acquisition of business, net of cash acquired Payments to acquire businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Derivative assets Derivative Asset, Current Other revenues Other Revenues Contracts [Member] Other revenues contracts: Contracts with customers for the sale of excess natural gas or natural gas liquids and certain ethane supply contracts to supply a stated volume to customers, and any volume requested above the stated volume is based on product availability. Local Phone Number Local Phone Number NYMEX/ICE Natural Gas Contracts NYMEX/ICE Natural Gas Contracts [Member] NYMEX/ICE Natural Gas Contracts Contract with customer, liability, noncurrent Contract with Customer, Liability, Noncurrent PBOP Other Postretirement Benefits Plan [Member] Costs associated with service revenues Costs Associated With Service Revenues Cost of goods purchased or services received to provide transportation and storage services other than product sales. Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Income before income taxes Consolidated income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Total operating revenues Total operating revenues Revenue from external customers Revenues Other Assets: Other Assets [Abstract] Operating Costs and Expenses: Operating Costs and Expenses [Abstract] LIABILITIES AND PARTNERS' CAPITAL Liabilities and Equity [Abstract] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Fair Value Disclosures [Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] Gas and NGLs stored underground and gas and NGLs receivables and payables Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables [Text Block] The entire disclosure regarding gas and liquids stored underground and gas and natural gas liquids receivables and payables. Reclassification adjustment transferred to Net income from cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Lessee, operating lease, term of contract Lessee, Operating Lease, Term of Contract Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Accrued liabilities Increase (Decrease) in Accrued Liabilities Contract liabilities from contracts with customers Beginning Balance Ending Balance Contract with Customer, Liability Financial Liabilities Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Less: Cash acquired Cash Acquired from Acquisition Property, Plant and Equipment, Type [Axis] Long-Lived Asset, Class [Axis] Entity Tax Identification Number Entity Tax Identification Number Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Legal Entity [Axis] Legal Entity [Axis] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Spire Marketing, Inc. Spire Marketing, Inc. [Member] Spire Marketing, Inc. Total projected operating revenues under committed firm agreements as of September 30, 2026 (2) Committed Firm Agreements Projected operating revenues under committed firm agreements. Trade and other payables Increase (Decrease) in Accounts Payable Entity Incorporation, State Entity Incorporation, State or Country Code Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Purchase price Payments to Acquire Businesses, Gross Other Business Combination, Recognized Liability Assumed, Other Liability, Noncurrent Boardwalk Pipelines Holding Corp. (BPHC) Boardwalk Pipelines Holding Corp. (BPHC) [Member] Boardwalk Pipelines Holding Corp. (BPHC) Leases Lessee, Operating Leases [Text Block] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Contract with customer, liability, current Contract with Customer, Liability, Current Total current assets Assets, Current Derivative Instruments, Gain (Loss) Derivative Instruments, Gain (Loss) [Table Text Block] Trade, net Accounts Receivable, after Allowance for Credit Loss, Current Costs associated with product sales Costs Associated With Product Sales Product costs incurred for natural gas or NGL product sold to customers during the reporting period. Product and Service [Axis] Product and Service [Axis] Partners' Capital: Partners' Capital [Abstract] Gas transportation receivables Oil and Gas, Gas-Balancing Arrangement, Asset (Liability) Pension Pension Plan [Member] Fair Value Fair Value Measurement [Domain] Former Address Former Address [Member] Additional annual operating lease cost Operating Lease, Cost Gas transportation payables Oil and Gas, Gas-Balancing Arrangement, Payable, Current Average market price of ethylene assumed (in dollars per pound) Average Market Price of Ethylene Assumed Average Market Price of Ethylene Assumed Cover page. Cover [Abstract] Gas stored underground and product inventory Energy Related Inventory 2027 Unrecorded Unconditional Purchase Obligation, to be Paid, Year One Derivative Contract [Domain] Derivative Contract [Domain] Unrecorded Unconditional Purchase Obligations Disclosure Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Business Acquisition [Line Items] Asset Acquisition [Line Items] Derivative liability, noncurrent Derivative Liability, Noncurrent Total Liabilities and Partners' Capital Liabilities and Equity Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Segments [Axis] Segments [Axis] Other liabilities Increase (Decrease) in Other Operating Liabilities Related Party, Type [Domain] Related and Nonrelated Parties [Domain] Miscellaneous other income, net Miscellaneous other income, net Other Nonoperating Income (Expense) Boardwalk Pipelines 5.375% Notes due 2036 Boardwalk Pipelines 5.375% Notes due 2036 [Member] Boardwalk Pipelines 5.375% Notes due 2036 Cash margin receivables offset with derivatives Cash Margin Receivables Offset With Derivatives mount of cash margin receivables associated with derivative instruments that are subject to master netting arrangements and are offset against derivative assets and derivative liabilities in the statement of financial position. Payables: Accounts Payable, Current [Abstract] Administrative and general General and Administrative Expense Property, Plant and Equipment, Type [Domain] Long-Lived Asset, Class [Domain] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Revenue remaining performance obligation, amount, precedent transportation agreements Revenue Remaining Performance Obligation, Amount, Precedent Transportation Agreements Amount of transaction price allocated to performance obligation that has not been recognized as revenue that are anticipated under precedent transportation agreements. Interest (net of amount capitalized) Interest Paid, Excluding Capitalized Interest, Operating Activity Statement of Cash Flows Statement of Cash Flows [Abstract] Forward natural gas contracts NYMEX/ICE natural gas contracts Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Assets, fair value, recurring Assets, Fair Value Disclosure Storage, parking and lending Storage, Parking And Lending Revenue Revenue related to providing storage, parking and lending services to customers. Long-term debt and finance lease obligation Long-Term Debt and Lease Obligation Amortization of deferred costs and other Amortization Of Deferred Costs And Other The amount of amortization of deferred and other charges applied against earnings during the period. Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Entity Filer Category Entity Filer Category Supplemental Cash Flow Elements [Abstract] Supplemental Cash Flow Elements [Abstract] Short-term investments Short-Term Investments Partners' capital General And Limited Partners' Capital Account The amount of the general partners and limited partners ownership interests. Effect of netting and cash margin receivables/payables, asset Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset Cash and cash equivalents Cash and Cash Equivalent Energy [Axis] Energy [Axis] Total Notes And Debentures Total Notes And Debentures [Member] Total notes and debentures as of period end. 2030 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four Entity Address, Address Line Two Entity Address, Address Line Two Statement of Partners' Capital [Abstract] Statement of Partners' Capital [Abstract] Current Assets: Assets, Current [Abstract] Derivative liability, total Derivative Liability Operating revenue Business Combination, Pro Forma Information, Pro Forma Revenue Other Deductions (Income): Interest and Debt Expense [Abstract] Entity Address, Address Line One Entity Address, Address Line One Right-of-use asset obtained in exchange for lease obligations Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Proceeds from the maturity of short-term investments Proceeds from Sale, Maturity and Collection of Short-Term Investments Income taxes Income Tax Expense (Benefit) (Decrease) increase in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Pipelines, storage and other plant Transmission Equipment And Other Plant Equipment [Member] Transmission, storage and other plant equipment used to provide transportation and storage services. Amortization of unrecognized net loss Defined Benefit Plan, Amortization of Gain (Loss) Net income Net income Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Unamortized debt issuance costs Unamortized Debt Issuance Expense Location, Statement of Financial Position, Balance [Axis] Location, Statement of Financial Position, Balance [Axis] Statement [Table] Statement [Table] Maximum Term (Months) Derivative, Contract Term Remaining Performance Obligation Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Interest income Investment Income, Interest Legal damages awarded to other party (approximately) Litigation Settlement, Amount Awarded to Other Party Total other liabilities and deferred credits Liabilities, Other than Long-Term Debt, Noncurrent Notional Activity [Line Items] Derivative Instruments Gain (Loss) Table[Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Contract Liabilities Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Receivables: Receivables, Net, Current [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Gas and NGLs stored underground and gas and NGLs receivables and payables Oil and Gas, Gas-Balancing Arrangement [Policy Text Block] Operating Revenues: Revenues [Abstract] Non-cash investing activities: Other Noncash Investing and Financing Items [Abstract] 2026 (1) Unrecorded Unconditional Purchase Obligation, to be Paid, Remainder of Fiscal Year Derivative Instruments and Hedging Activities Disclosure [Abstract]