RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivative, Fair Value [Line Items]
Assets	$ 46,859	$ 67,030
(Liabilities)	(292,740)	(231,537)
Derivative, Net Liability Position, Aggregate Fair Value	0
Cash posted - offsetting derivative net liability positions under master-netting arrangements	13,900
Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	46,451	67,030
(Liabilities)	(292,364)	(231,537)
Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	408	0
(Liabilities)	(376)	0
Natural Gas Pipelines
Derivative, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Other Current Assets [Member] \| Commodity contracts \| Financial contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	46,451	64,858
(Liabilities)	(60,373)	(26,997)
Other Current Assets [Member] \| Commodity contracts \| Financial contracts \| Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	408	0
(Liabilities)	(376)	0
Other Current Liabilities [Member] \| Interest-rate contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	0
(Liabilities)	0	(90,161)
Other Deferred Credits \| Commodity contracts \| Financial contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	1,591
(Liabilities)	0	(2,599)
Other Deferred Credits \| Interest-rate contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	581
(Liabilities)	$ (231,991)	(111,780)
Interest-rate contracts \| LIBOR Based Interest Payments [Member] \| Cash Flow Hedging [Member] \| Forward contracts
Derivative, Fair Value [Line Items]
Derivative, Notional Amount		$ 1,300,000

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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