Financing - Debt (Details) - USD ($) $ in Millions				3 Months Ended
		Mar. 21, 2022	Feb. 28, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Debt Instrument [Line Items]
Current portion of long-term debt				$ 300.0		$ 0.0
Repayment of borrowings from long-term debt				300.0	$ 0.0
Unsecured Debt
Debt Instrument [Line Items]
Long-term Debt, Gross				$ 3,600.0		$ 3,400.0
Debt, Weighted-Average Interest Rate				4.72%		4.84%
Current portion of long-term debt				$ 300.0
Debt Instrument, Covenant Compliance				As of March 31, 2022, Boardwalk Pipelines and its operating subsidiaries were in compliance with their debt covenants.
Unsecured Debt | Boardwalk Pipelines 3.60% Notes Due 2032
Debt Instrument [Line Items]
Debt Instrument, Issuance Date			Feb. 28, 2022
Debt Instrument, Face Amount			$ 500.0
Payments of Debt Issuance Costs			5.0
Proceeds from Debt, Net of Issuance Costs	[1]		$ 495.0
Debt Instrument, Interest Rate, Stated Percentage			3.60%
Debt Instrument, Maturity Date			Sep. 01, 2032
Unsecured Debt | Gulf South 4.0% Notes Due 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.00%
Repayment of borrowings from long-term debt		$ 300.0
Line of Credit
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 Facility, Covenant Compliance				The Company and its subsidiaries were in compliance with all covenant requirements under the revolving credit facility as of March 31, 2022.
Line of Credit | Amendment No. 3 Credit Agreement - 2021
Line of Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,000.0

[1] The net proceeds of this offering were used to retire the outstanding $300.0 million aggregate principal amount of Gulf South 4.00% notes due June 2022 on March 21, 2022, to fund growth capital expenditures and for general partnership purposes.