Long-term Debt (Schedule Of Long-term Debt) (Parenthetical) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
$250,000,000 principal amount of First Mortgage Bonds, 2017 Series A due 2037 at an interest rate of 3.33%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250,000,000	$ 250,000,000
Debt instrument, interest rate	3.33%	3.33%
$260,000,000 principal amount of First Mortgage Bonds, 2015 Series A due 2044 at an interest rate of 4.46%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 260,000,000	$ 260,000,000
Debt instrument, interest rate	4.46%	4.46%
$72,000,000 principal amount of First Mortgage Bonds, 2015 Series B due 2053 at an interest rate of 4.56%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 72,000,000	$ 72,000,000
Debt instrument, interest rate	4.56%	4.56%
$50,000,000 principal amount of First Mortgage Bonds, 2013 Series A due 2043 at an interest rate of 4.21%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 50,000,000	$ 50,000,000
Debt instrument, interest rate	4.21%	4.21%
$50,000,000 principal amount of First Mortgage Bonds, 2013 Series B due 2053 at an interest rate of 4.36%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 50,000,000	$ 50,000,000
Debt instrument, interest rate	4.36%	4.36%
$90,000,000 principal amount of First Mortgage Bonds, 2011 Series A due 2040 at an interest rate of 4.83%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 90,000,000	$ 90,000,000
Debt instrument, interest rate	4.83%	4.83%
$165,000,000 principal amount of First Mortgage Bonds, 2011 Series B due 2040 at an interest rate of 5.54%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 165,000,000	$ 165,000,000
Debt instrument, interest rate	5.54%	5.54%
$95,000,000 principal amount of First Mortgage Bonds, 2011 Series C due 2050 at an interest rate of 5.54%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 95,000,000	$ 95,000,000
Debt instrument, interest rate	5.54%	5.54%
$250,000,000 principal amount of 2003 Series A Bonds due 2028 at an interest rate of 5.676%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250,000,000	$ 250,000,000
Debt instrument, interest rate	5.676%	5.676%
$300,000,000 principal amount of 2002 Series B Bonds due 2028 at an interest rate of 6.21%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 300,000,000	$ 300,000,000
Debt instrument, interest rate	6.21%	6.21%