COMMITMENTS AND CONTINGENCIES (Narrative) (Details) $ in Millions, $ in Millions |
6 Months Ended | |||
---|---|---|---|---|
Jun. 30, 2018
USD ($)
|
Jun. 30, 2018
CAD ($)
|
Jan. 01, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
|
|
Loss Contingencies [Line Items] | ||||
Loans to and accounts receivable from the Canadian Entities | $ 0.0 | $ 51.6 | $ 51.6 | |
Cash contribution | $ 19.0 | |||
Michigan Electricity Matters [Member] | ||||
Loss Contingencies [Line Items] | ||||
Loss Contingency Accrual | 10.8 | $ 13.0 | ||
Loss Contingency Accrual, Period Increase (Decrease) | $ 2.2 |