Financing Activity - Carrying and Fair Values of Mortgage Loans (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Mortgage Loan
Debt Instrument [Line Items]
Debt issuance costs, line of credit arrangements	$ 1.7	$ 2.1

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.

No definition available.

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant