REVENUE - Member (Details)	12 Months Ended
	Dec. 31, 2019 item customer
Member electric sales
Number of billing components of Class A rate schedule for electric power sales to Members | item	3
Number of demand rates | item	2
Member Contracts Extending Through 2050
Member electric sales
Number of contracts | customer	42
Member Contracts Extending Through 2040
Member electric sales
Number of contracts | customer	1