Consolidated Statements Of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 224,688,669	$ 197,747,579	$ 216,421,152
Operating expenses:
Fuel	78,552,672	54,778,582	66,534,877
Production	18,006,490	15,809,168	16,886,257
Purchased power	17,301,067	15,774,733	19,599,994
Transmission	6,129,871	5,590,737	6,287,558
Distribution	13,991,088	13,991,997	14,089,862
Consumer accounts	5,968,736	6,073,710	6,117,625
Administrative, general and other	23,256,983	22,888,048	23,623,299
Depreciation and amortization	34,010,777	36,233,414	35,652,086
Total operating expenses	197,217,684	171,140,389	188,791,558
Interest expense:
Long-term debt and other	22,366,034	21,856,095	22,194,290
Charged to construction	(164,898)	(454,798)	(379,845)
Interest expense, net	22,201,136	21,401,297	21,814,445
Net operating margins	5,269,849	5,205,893	5,815,149
Nonoperating margins:
Interest income	644,663	425,173	296,788
Allowance for funds used during construction	69,157	188,111	142,881
Capital credits, patronage dividends and other	65,055	(5,321)	248,034
Total nonoperating margins	778,875	607,963	687,703
Assignable margins	$ 6,048,724	$ 5,813,856	$ 6,502,852