DERIVATIVES AND HEDGING ACTIVITIES Schedule of Notional Amounts of Financial Instruments (Details) € in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($) MWh	Dec. 31, 2020 USD ($) MWh	Mar. 31, 2021 EUR (€)	Dec. 31, 2020 EUR (€)
Energy Related Derivative | Not Designated as Hedging Instrument
Derivative [Line Items]
Underlying, Derivative Energy Measure | MWh	200,000	200,000
Cash Flow Hedging | Foreign Exchange Contract | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Notional Amount	$ 112	$ 85	€ 192	€ 187
Net Investment Hedging [Member] | Foreign Exchange Contract | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Notional Amount | €			€ 670	€ 0