Consolidated Statements of Revenues and Expenses (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating revenues:
Total operating revenues	$ 376,331	$ 341,674
Operating expenses:
Fuel	108,065	71,156
Production	105,373	116,131
Depreciation and amortization	67,619	62,024
Purchased power	16,920	16,613
Accretion	13,781	13,235
Total operating expenses	311,758	279,159
Operating margin	64,573	62,515
Other income:
Investment income	11,960	12,934
Other	2,171	2,009
Total other income	14,131	14,943
Interest charges:
Interest expense	103,479	102,285
Allowance for debt funds used during construction	(53,639)	(51,030)
Amortization of debt discount and expense	2,906	2,999
Net interest charges	52,746	54,254
Net margin	25,958	23,204
Members
Operating revenues:
Total operating revenues	376,272	341,513
Non-Members
Operating revenues:
Total operating revenues	$ 59	$ 161