XML 72 R58.htm IDEA: XBRL DOCUMENT v3.3.1.900
INCOME TAXES - Effective Tax Rate Reconciliation (Details)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Reconciliation between the statutory federal income tax rate and the effective tax rate      
Federal income tax expense at statutory rate 35.00% 35.00% 35.00%
State income tax expense, net of federal benefit 2.63% 2.63% 2.63%
Patronage exclusion (37.63%) (37.63%) (37.63%)
Asset retirement obligations (0.58%) 1.40% (6.74%)
Postretirement medical actuarial gains and losses (1.09%) 2.44% 0.18%
Various book tax differences 2.84% 4.52% 8.93%
Regulatory treatment of deferred taxes (1.17%) (8.36%) (2.37%)
Effective tax rate 0.00% 0.00% 0.00%