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RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Part 2 (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 USD ($) MMcf MMBbls | Dec. 31, 2017 USD ($) MMcf MMBbls | Sep. 30, 2017 USD ($)
Derivative [Line Items] |  |  |
Senior Notes, Noncurrent | $ 1,250.0 |  | $ 1,200.0
Derivatives designated as hedging instruments | Futures and swaps | Natural gas (Bcf) | Fixed price | Purchased/Payor |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMcf | 0 | 0 |
Derivatives designated as hedging instruments | Futures and swaps | Natural gas (Bcf) | Fixed price | Sold/Receiver |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMcf | (29,900) | (24,500) |
Derivatives designated as hedging instruments | Futures and swaps | Natural gas (Bcf) | Basis | Purchased/Payor |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMcf | 0 | 0 |
Derivatives designated as hedging instruments | Futures and swaps | Natural gas (Bcf) | Basis | Sold/Receiver |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMcf | (29,900) | (24,500) |
Derivatives designated as hedging instruments | Futures, forwards and swaps | Crude oils and NGLs (MMBbl) | Fixed price | Purchased/Payor |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMBbls | 6.5 | 3.5 |
Derivatives designated as hedging instruments | Futures, forwards and swaps | Crude oils and NGLs (MMBbl) | Fixed price | Sold/Receiver |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMBbls | (13.8) | (11.1) |
Derivatives designated as hedging instruments | Interest Rate Contracts | Purchased/Payor |  |  |
Derivative [Line Items] |  |  |
Derivative, Notional Amount | $ 4,250.0 | $ 1,750.0 |
Derivatives designated as hedging instruments | Interest Rate Contracts | Sold/Receiver |  |  |
Derivative [Line Items] |  |  |
Derivative, Notional Amount | $ 0.0 | $ 0.0 |
Derivatives not designated as hedging instruments | Futures, forwards and swaps | Crude oils and NGLs (MMBbl) | Fixed price | Purchased/Payor |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMBbls | 0.0 | 0.8 |
Derivatives not designated as hedging instruments | Futures, forwards and swaps | Crude oils and NGLs (MMBbl) | Fixed price | Sold/Receiver |  |  |
Derivative [Line Items] |  |  |
Notional amount | MMBbls | 0.0 | (0.8) |
LIBOR Based Interest Payments [Member] | Cash Flow Hedging [Member] | Forward contracts | Interest Rate Contracts |  |  |
Derivative [Line Items] |  |  |
Notional Amount Of Cash Flow Hedge Instruments Settled | $ 500.0 |  |
Derivative, Notional Amount | 1,300.0 | $ 500.0 |
Forecasted Debt Issuances [Member] | Cash Flow Hedging [Member] | Forward contracts | Interest Rate Contracts |  |  |
Derivative [Line Items] |  |  |
Notional Amount Of Cash Flow Hedge Instruments Settled | 1,000.0 |  |
Derivative, Notional Amount | 3,000.0 | $ 1,300.0 |
Derivative, Notional Amount, New Contracts | $ 2,800.0 |  |

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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