MAJOR CUSTOMERS AND CONCENTRATION OF CREDIT RISK (Details) - Accounts receivable - Credit Concentration Risk	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Southern Nuclear Operating Company
Concentration Risk
Concentration risk percentage	45.00%	34.00%
Tennessee Valley Authority
Concentration Risk
Concentration risk percentage		11.00%
Energy Northwest
Concentration Risk
Concentration risk percentage		10.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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