Risk Management and Derivative Instruments - Gross Fair Value of Derivative Instruments by Appropriate Balance Sheet (Detail) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Derivative Instruments and Hedges, Assets [Abstract]
Cash collateral received	$ 0	$ 0
Cash collateral pledged	0	0
Short-Term Derivative Instruments [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	6,046,000	4,804,000
Asset Derivatives, Netting arrangements	(5,604,000)	(4,804,000)
Asset Derivatives, Net recorded fair value	442,000	0
Liability Derivatives, Gross fair value	50,471,000	57,948,000
Liability Derivatives, Netting arrangements	(5,604,000)	(4,804,000)
Liability Derivatives, Net recorded fair value	44,867,000	53,144,000
Short-Term Derivative Instruments [Member] | Commodity derivatives [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	5,604,000	4,804,000
Liability Derivatives, Gross fair value	50,471,000	57,325,000
Short-Term Derivative Instruments [Member] | Interest Rate Swaps [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	442,000	0
Liability Derivatives, Gross fair value	0	623,000
Long-Term Derivative Instruments [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	2,030,000	3,163,000
Asset Derivatives, Netting arrangements	(2,030,000)	(3,163,000)
Asset Derivatives, Net recorded fair value	0	0
Liability Derivatives, Gross fair value	7,714,000	12,827,000
Liability Derivatives, Netting arrangements	(2,030,000)	(3,163,000)
Liability Derivatives, Net recorded fair value	5,684,000	9,664,000
Long-Term Derivative Instruments [Member] | Commodity derivatives [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	2,030,000	3,163,000
Liability Derivatives, Gross fair value	7,714,000	12,827,000
Long-Term Derivative Instruments [Member] | Interest Rate Swaps [Member]
Derivative Instruments and Hedges, Assets [Abstract]
Asset Derivatives, Gross fair value	0	0
Liability Derivatives, Gross fair value	$ 0	$ 0