Debt Debt (Schedule of Long Term Debt Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Unsecured Debt	$ 400,000
Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months	75,389
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	475,408
Long-term Debt, Maturities, Repayments of Principal in Year Three	75,425
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Four	125,816
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Five	0
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	497,079
Long-term Debt, Gross	1,249,117
Less: unamortized loan costs	6,234	$ 4,069
Debt	1,242,883	1,499,285
Private Placement [Member]
Debt Instrument [Line Items]
Unsecured Debt	400,000	$ 400,000
January 2023 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 125,000
Debt Instrument, Interest Rate, Stated Percentage	3.99%
November 2023 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 50,000
Debt Instrument, Interest Rate, Stated Percentage	3.99%
September 2024 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 75,000
Debt Instrument, Interest Rate, Stated Percentage	3.93%
November 2025 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 50,000
Debt Instrument, Interest Rate, Stated Percentage	4.33%
January 2027 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 100,000
Debt Instrument, Interest Rate, Stated Percentage	4.51%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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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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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.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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