RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivative, Fair Value [Line Items]
Assets	$ 120,397	$ 110,498
(Liabilities)	(271,919)	(349,018)
Derivative, Net Liability Position, Aggregate Fair Value	0
Cash posted - offsetting derivative net liability positions under master-netting arrangements	54,400	35,100
Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	114,150	107,461
(Liabilities)	(265,732)	(345,980)
Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	6,247	3,037
(Liabilities)	(6,187)	(3,038)
Natural Gas Pipelines
Derivative, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Other Current Assets [Member] \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	241	0
Other Current Liabilities [Member] \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(65,329)	0
Other Deferred Credits \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	0
(Liabilities)	(32,034)	(203,407)
Fully Netted Assets/Liabilities \| Commodity Contracts \| Financial contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	113,909	107,461
(Liabilities)	(168,369)	(142,573)
Fully Netted Assets/Liabilities \| Commodity Contracts \| Financial contracts \| Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	6,247	3,037
(Liabilities)	$ (6,187)	$ (3,038)

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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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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