Fair Value SUmmary of fair value Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 2,647	$ 2,586
Financial Transmission Rights Fair Value Disclosure	2,657	3,099
Assets, Fair Value Disclosure	5,304	5,685
Interest Rate Cash Flow Hedge Liability at Fair Value	23,054	0
Derivative Liability		53
Financial and Nonfinancial Liabilities, Fair Value Disclosure	23,054	53
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19	21
Financial Transmission Rights Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	19	21
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	2,628	2,565
Financial Transmission Rights Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	2,628	2,565
Interest Rate Cash Flow Hedge Liability at Fair Value	23,054
Derivative Liability		0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	23,054	0
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	2,657	3,099
Assets, Fair Value Disclosure	2,657	3,099
Interest Rate Cash Flow Hedge Liability at Fair Value	0
Derivative Liability		53
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	53
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19	21
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	19	21
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	2,628	2,565
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	2,628	2,565
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