Financing - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2025	Nov. 30, 2025	Dec. 31, 2024
Debt Instruments [Abstract]
Finance lease obligation	$ 1.7		$ 2.7
Total Notes and Debentures and Finance Lease Obligation	3,801.7		3,252.7
Less:
Total Debt and Finance Lease Obligation	3,781.4		3,234.4
Current portion of long-term debt	549.6		0.0
Total Long-Term Debt and Finance Lease Obligation	3,231.8		3,234.4
Unsecured Debt
Debt Instruments [Abstract]
Total notes and debentures	3,800.0
Less:
Unamortized debt discount	(14.8)		(13.5)
Unamortized debt issuance costs	$ (5.5)		$ (4.8)
Unsecured Debt \| Boardwalk Pipelines 5.95% Notes Due 2026
Debt Instruments [Abstract]
Debt, interest rate	5.95%		5.95%
Total notes and debentures	$ 550.0		$ 550.0
Unsecured Debt \| Boardwalk Pipelines 4.45% Notes Due 2027
Debt Instruments [Abstract]
Debt, interest rate	4.45%		4.45%
Total notes and debentures	$ 500.0		$ 500.0
Unsecured Debt \| Boardwalk Pipelines 4.80% Notes Due 2029
Debt Instruments [Abstract]
Debt, interest rate	4.80%		4.80%
Total notes and debentures	$ 500.0		$ 500.0
Unsecured Debt \| Boardwalk Pipelines 3.40% Notes Due 2031
Debt Instruments [Abstract]
Debt, interest rate	3.40%		3.40%
Total notes and debentures	$ 500.0		$ 500.0
Unsecured Debt \| Boardwalk Pipelines 3.60% Notes Due 2032
Debt Instruments [Abstract]
Debt, interest rate	3.60%		3.60%
Total notes and debentures	$ 500.0		$ 500.0
Unsecured Debt \| Boardwalk Pipelines 5.625% Notes Due 2034
Debt Instruments [Abstract]
Debt, interest rate	5.625%		5.625%
Total notes and debentures	$ 600.0		$ 600.0
Unsecured Debt \| Boardwalk Pipelines 5.375% Notes due 2036
Debt Instruments [Abstract]
Debt, interest rate	5.375%	5.375%
Total notes and debentures	$ 550.0		$ 0.0
Unsecured Debt \| Texas Gas 7.25% Debentures Due 2027
Debt Instruments [Abstract]
Debt, interest rate	7.25%		7.25%
Total notes and debentures	$ 100.0		$ 100.0
Unsecured Debt \| Total Notes and Debentures
Debt Instruments [Abstract]
Total notes and debentures	$ 3,800.0		$ 3,250.0

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- Definition

Amount of short-term and long-term debt and lease obligation.

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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.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount.

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

+ References

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Amount of long-term debt and lease obligation, including portion classified as current.

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- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as current. Excludes lease obligation.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

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