Number of extensions available under the debt instrument.

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Term of the extension of the debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Additional 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.

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No definition available.

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Face (par) amount of debt instrument at time of issuance.

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

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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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.

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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.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Debt - Narrative (Details)	1 Months Ended	12 Months Ended
Debt - Narrative (Details)	Nov. 30, 2022 USD ($)	Dec. 31, 2019 USD ($) Extension	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 01, 2021 USD ($)
Debt [Abstract]
Long term debt maturing in 2023			$ 855,000,000
Long term debt maturing in 2024			1,500,000,000
Long term debt maturing in 2025			3,000,000
Long term debt maturing in 2026			1,600,000,000
Long term debt maturing in 2027			1,100,000,000
Long term debt maturing thereafter			4,000,000,000
CNA
Debt [Abstract]
FHLBC stock held			5,000,000
Additional liquidity available			106,000,000
Outstanding borrowings from FHLBC			0			$ 0
CNA \| Senior unsecured revolving credit facility
Debt [Abstract]
Term		5 years
Maximum borrowing capacity		$ 250,000,000
Additional borrowing capacity		$ 100,000,000
Number of extensions \| Extension		2
Term of extension		1 year
Outstanding borrowings			0
Boardwalk Pipelines \| Senior Notes Due 2032
Debt [Abstract]
Face amount					$ 500,000,000
Interest rate					3.60%
Boardwalk Pipelines \| 4.0% Senior Notes Due 2022
Debt [Abstract]
Face amount			$ 300,000,000	$ 300,000,000
Interest rate			4.00%	4.00%
Boardwalk Pipelines \| 3.4% Senior Notes due 2023
Debt [Abstract]
Face amount	$ 300,000,000
Interest rate	3.40%
Redemption price, percentage	100.00%
Boardwalk Pipelines \| Senior Variable Rate Revolving Credit Facility Due 2026
Debt [Abstract]
Maximum borrowing capacity							$ 1,000,000,000
Boardwalk Pipelines \| Revolving Credit Facility Due 2022
Debt [Abstract]
Outstanding borrowings			$ 0
Remaining borrowing capacity			$ 1,000,000,000