v3.10.0.1
FAIR VALUE OF FINANCIAL INSTRUMENTS - Non-Recurring basis (Details)
$ in Millions
9 Months Ended
Sep. 30, 2018
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Impairment - Market Assets $ 2.1
Impairment - Assets Held for Sale 26.9
Impairment - Bonneville Assets held for Sale 25.6
Impairment - Other assets held for sale $ 1.3