Risk Management - Energy Commodity Price Risk Management (Details) - Short [Member] - Energy commodity derivative contracts	12 Months Ended
	Dec. 31, 2019 Bcf MMBbls
Designated as Hedging Instrument | Crude Oil Fixed Price
Derivative [Line Items]
Net open position long/(short)	(19.6)
Designated as Hedging Instrument | Crude Oil Basis
Derivative [Line Items]
Net open position long/(short)	(7.2)
Designated as Hedging Instrument | Natural Gas Fixed Price
Derivative [Line Items]
Net open position long/(short) | Bcf	(30.8)
Designated as Hedging Instrument | Natural Gas Basis
Derivative [Line Items]
Net open position long/(short) | Bcf	(22.3)
Designated as Hedging Instrument | NGL Fixed Price
Derivative [Line Items]
Net open position long/(short)	(1.3)
Not Designated as Hedging Instrument | Crude Oil Fixed Price
Derivative [Line Items]
Net open position long/(short)	(0.8)
Not Designated as Hedging Instrument | Crude Oil Basis
Derivative [Line Items]
Net open position long/(short)	(4.1)
Not Designated as Hedging Instrument | Natural Gas Fixed Price
Derivative [Line Items]
Net open position long/(short) | Bcf	(5.2)
Not Designated as Hedging Instrument | Natural Gas Basis
Derivative [Line Items]
Net open position long/(short) | Bcf	(8.8)
Not Designated as Hedging Instrument | NGL Fixed Price
Derivative [Line Items]
Net open position long/(short)	(1.9)