Annual report pursuant to Section 13 and 15(d)

MAJOR CUSTOMERS AND CONCENTRATION OF CREDIT RISK Risk (Details)

v3.19.1
MAJOR CUSTOMERS AND CONCENTRATION OF CREDIT RISK Risk (Details) - Revenue - Customer Concentration Risk
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Southern Nuclear Operating Company    
Concentration Risk    
Concentration risk percentage 25.00% 22.00%
Tennessee Valley Authority    
Concentration Risk    
Concentration risk percentage 26.00% 22.00%
Richmond County Constructors    
Concentration Risk    
Concentration risk percentage 18.00%  
Energy Northwest    
Concentration Risk    
Concentration risk percentage   15.00%
All Others    
Concentration Risk    
Concentration risk percentage 31.00% 41.00%
Concentration risk percentage 100.00% 100.00%