Fair Value Summary of fair value Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 3,657	$ 3,225
Financial Transmission Rights Fair Value Disclosure	1,842	543
Assets, Fair Value Disclosure	5,813	3,768
Interest Rate Cash Flow Hedge Liability at Fair Value	44,816
Derivative Liability		63,215
Financial and Nonfinancial Liabilities, Fair Value Disclosure	44,816	63,215
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	14	16
Financial Transmission Rights Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	14	16
Interest Rate Cash Flow Hedge Liability at Fair Value	0
Derivative Liability		0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	3,643	3,209
Financial Transmission Rights Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	3,957	3,209
Interest Rate Cash Flow Hedge Liability at Fair Value	44,816
Derivative Liability		63,215
Financial and Nonfinancial Liabilities, Fair Value Disclosure	44,816	63,215
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0	0
Financial Transmission Rights Fair Value Disclosure	1,842	543
Assets, Fair Value Disclosure	1,842	543
Interest Rate Cash Flow Hedge Liability at Fair Value	0
Derivative Liability		0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	14	16
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	14	16
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	3,643	3,209
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	3,643	3,209
Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 0	$ 0