Summary Of Significant Accounting Policies - Additional Information (Details)			12 Months Ended
	Dec. 14, 2021 USD ($)	Nov. 19, 2019 USD ($)	Dec. 31, 2021 USD ($) member_class member representative Cooperative product segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Significant Accounting Policies [Line Items]
Consolidated assets			$ 2,175,059,000	$ 2,067,644,000
Number of classes of members | member_class			2
Number of Class A members | member			11
Number of representatives from each Class A member on the board of directors | representative			2
Number of representatives from each Class B member on the board of directors | representative			1
Frequency of depreciation study			5 years
Reimbursement of nuclear fuel costs receivable			$ 2,400,000	3,200,000
Interest costs capitalized			$ 900,000	500,000	$ 500,000
Number of Member Distributions Cooperatives | Cooperative			11
Non-member energy sales			$ 53,740,000	36,890,000	34,211,000
Number of power products for sale | product			2
Percentage change in energy rate due to revision of energy adjustment rate			2.00%
Percentage of budgeted total interest charges			20.00%
Percentage of actual interest charges			20.00%
Deferred energy, asset			$ 5,000,000.0
Deferred energy, liability				23,100,000
Additional equity contribution	$ 8,700,000	$ 4,300,000
Retirement of patronage capital	$ 8,700,000	$ 4,300,000	8,740,000		4,306,000
Payment date of patronage capital	Mar. 25, 2022	Mar. 27, 2020
Reduction of patronage capital	$ 8,700,000	$ 4,300,000
Increase in accounts payable-members	$ 8,700,000	$ 4,300,000
Accounts receivable–members			$ 63,037,000	79,813,000
Number of operating segments | segment			1
Number of reportable segments | segment			1
Long-term Debt [Member]
Significant Accounting Policies [Line Items]
Capitalized costs associated with the issuance of debt			$ 5,200,000	5,700,000
Deferred Charges And Other Assets - Other [Member]
Significant Accounting Policies [Line Items]
Capitalized costs associated with the issuance of debt			600,000	900,000
Variable Interest Entity Primary Beneficiary [Member]
Significant Accounting Policies [Line Items]
Consolidated assets			5,800,000	5,800,000
Non-member energy sales			$ 0	0	0
Maximum [Member]
Significant Accounting Policies [Line Items]
Ownership interest recorded using the equity method of accounting			50.00%
Derivative term			3 years
TEC [Member]
Significant Accounting Policies [Line Items]
Percentage of interest owned in subsidiary by our Class A members			100.00%
Non-member energy sales			$ 0	$ 0	$ 0