Financing - Debt (Details) - USD ($) $ in Millions				12 Months Ended
		Aug. 31, 2020	May 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 04, 2022
Debt Instruments [Abstract]
Finance lease obligation				$ 5.3	$ 6.1
Debt and Lease Obligation				3,355.3	3,486.1
Unamortized debt discount				(16.0)	(19.6)
Unamortized debt issuance costs				(4.8)	(5.8)
Long-term debt and finance lease obligation				3,334.5	3,460.7
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt				0.0	$ 440.0	$ 350.0
Unsecured Debt
Debt Instruments [Abstract]
Long-term Debt, Gross				3,350.0
Long-term Debt, Fiscal Year Maturity [Abstract]
2022				300.0
2023				300.0
2024				600.0
2025				0.0
2026				550.0
Thereafter				$ 1,600.0
Debt, Weighted-Average Interest Rate				4.84%	4.84%
Debt Instrument, Redemption Price, Percentage - equal to the greater of				100.00%
Line of Credit Facility [Abstract]
Short-term Debt, Refinanced, Description				The Company has included the Gulf South Notes which mature in less than one year as long-term debt on its Consolidated Balance Sheets as of December 31, 2021. The Company has the intent and the ability to refinance the notes through the available borrowing capacity under its revolving credit facility as of December 31, 2021.
Debt Instrument, Redemption, Description				The Company's notes and debentures are redeemable, in whole or in part, at the Company's option at any time, at a redemption price equal to the greater of 100% of the principal amount of the notes to be redeemed or a “make whole” redemption price based on the remaining scheduled payments of principal and interest discounted to the date of redemption at a rate equal to the Treasury rate plus 20 to 50 basis points depending upon the particular issue of notes, plus accrued and unpaid interest, if any. Other customary covenants apply, including those concerning events of default.
Debt Instrument, Covenant Description				The indentures governing the notes and debentures have restrictive covenants which provide that, with certain exceptions, neither the Company nor any of its subsidiaries may create, assume or suffer to exist any lien upon any property to secure any indebtedness unless the debentures and notes shall be equally and ratably secured. All of the Company's debt obligations are unsecured.
Debt Instrument, Covenant Compliance				As of December 31, 2021, Boardwalk Pipelines and its operating subsidiaries were in compliance with their debt covenants.
Unsecured Debt | Boardwalk Pipelines 3.375% Notes Due 2023
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 300.0	$ 300.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				3.375%	3.375%
Unsecured Debt | Boardwalk Pipelines 4.95% Notes Due 2024
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 600.0	$ 600.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.95%	4.95%
Unsecured Debt | Boardwalk Pipelines 5.95% Notes Due 2026
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 550.0	$ 550.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				5.95%	5.95%
Unsecured Debt | Boardwalk Pipelines 4.45% Notes Due 2027
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500.0	$ 500.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.45%	4.45%
Unsecured Debt | Boardwalk Pipelines 4.8% Notes Due 2029
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500.0	$ 500.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Issuance Date			May 31, 2019
Debt Instrument, Face Amount			$ 500.0
Payments of Debt Issuance Costs			4.8
Proceeds from Debt, Net of Issuance Costs	[1]		$ 495.2
Debt Instrument, Interest Rate, Stated Percentage			4.80%	4.80%	4.80%
Debt Instrument, Maturity Date			May 03, 2029
Unsecured Debt | Boardwalk Pipelines 3.40% Notes Due 2031
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500.0	$ 500.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Issuance Date		Aug. 31, 2020
Debt Instrument, Face Amount		$ 500.0
Payments of Debt Issuance Costs		5.0
Proceeds from Debt, Net of Issuance Costs	[2]	$ 495.0
Debt Instrument, Interest Rate, Stated Percentage		3.40%		3.40%
Debt Instrument, Maturity Date		Feb. 15, 2031
Unsecured Debt | Gulf South 4.00% Notes Due 2022
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 300.0	$ 300.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.00%	4.00%
Short-term Debt, Refinanced, Amount				$ 300.0
Unsecured Debt | Texas Gas 7.25% Debentures Due 2027
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 100.0	$ 100.0
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				7.25%	7.25%
Unsecured Debt | Total Notes and Debentures
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 3,350.0	$ 3,350.0
Unsecured Debt | Texas Gas 4.50% Notes Due 2021
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage					4.50%
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt					$ 440.0
Unsecured Debt | Boardwalk Pipelines 5.75% Notes Due 2019
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage						5.75%
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt						$ 350.0
Line of Credit
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt, Weighted-Average Interest Rate					1.39%
Line of Credit Facility [Abstract]
Maximum Ratio of Debt to EBITDA				5.0 to 1.0
Maximum Ratio of Debt to EBITDA after Acquisition				5.5 to 1.0
Qualified Acquisition Purchase Price Target (greater than)				$ 100.0
Long-term Line of Credit				0.0	$ 130.0
Line of Credit Facility, Remaining Borrowing Capacity				$ 1,000.0
Line of Credit Facility, Covenant Terms				The Credit Agreement contains various restrictive covenants and other usual and customary terms and conditions, including restrictions regarding the incurrence of additional debt, the sale of assets and sale-leaseback transactions. The financial covenants under the Credit Agreement require the Company and its subsidiaries to maintain, among other things, a ratio of total consolidated debt to consolidated EBITDA (as defined in the Credit Agreement) measured for the previous twelve months of not more than 5.0 to 1.0, or up to 5.5 to 1.0 for (i) the quarter in which the consummation of a qualified acquisition or series of acquisitions, where the purchase price exceeds $100.0 million over a rolling 12-month period and (ii) the three quarters following the qualified acquisition quarter.
Line of Credit Facility, Covenant Compliance				The Company and its subsidiaries were in compliance with all covenant requirements under the Credit Agreement as of December 31, 2021.
Line of Credit | Subsequent Event
Line of Credit Facility [Abstract]
Long-term Line of Credit							$ 0.0
Line of Credit Facility, Remaining Borrowing Capacity							$ 1,000.0
Line of Credit | Minimum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage				0.10%
Line of Credit | Maximum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage				0.275%
Line of Credit | Base Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				base rate
Line of Credit | Base Rate | Minimum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				0.00%
Line of Credit | Base Rate | Maximum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				0.75%
Line of Credit | Prime Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				prime rate
Line of Credit | Federal Funds Effective Swap Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				federal funds
Debt Instrument, Basis Spread on Variable Rate				0.50%
Line of Credit | Eurodollar
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				one month Eurodollar Rate
Debt Instrument, Basis Spread on Variable Rate				1.00%
Line of Credit | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				LIBOR
Line of Credit | London Interbank Offered Rate (LIBOR) | Minimum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				1.00%
Line of Credit | London Interbank Offered Rate (LIBOR) | Maximum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				1.75%
Line of Credit | Gulf South Revolving Credit Facility
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 0.0	30.0
Line of Credit | Texas Gas Revolving Credit Facility
Debt Instruments [Abstract]
Long-term Debt, Gross				0.0	$ 100.0
Line of Credit | Amendment No. 3 Credit Agreement - 2021
Line of Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,000.0
Line of Credit Facility, Expiration Date				May 27, 2026
Maturity date extension term				2 years

[1] The net proceeds of this offering were used to retire the outstanding $350.0 million aggregate principal amount of Boardwalk Pipelines 5.75% notes due 2019 at maturity and for general partnership purposes.

[2] The net proceeds of this offering were used to retire the outstanding $440.0 million aggregate principal amount of Texas Gas 4.50% notes due 2021 on November 3, 2020, to fund growth capital expenditures and for general partnership purposes.