Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	$ 4,909	$ 75,506
Derivative liabilities	63,089	85,106
Derivative Asset, Noncurrent	2,152	25,449
Derivative Liability, Noncurrent	21,416	28,434
Derivative Liability	84,505	113,540
Derivative Asset	7,061	100,955
Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative Liability	74,900
Commodity contracts \| Current Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	4,909	75,506
Derivative liabilities	60,593	81,451
Commodity contracts \| Noncurrent Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Noncurrent	2,152	25,449
Derivative Liability, Noncurrent	21,416	26,789
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability	2,500
Interest Rate Swap \| Current Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	0	0
Derivative liabilities	2,496	3,655
Interest Rate Swap \| Noncurrent Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Noncurrent	0	0
Derivative Liability, Noncurrent	0	1,645
Fair Value, Measurements, Recurring \| Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	4,909	75,506
Derivative liabilities	60,593	(81,451)
Derivative Asset, Noncurrent	2,152	25,449
Derivative Liability, Noncurrent	21,416	$ 26,789
Fair Value, Measurements, Recurring \| Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative liabilities	2,496
Derivative Liability, Noncurrent	$ 0

Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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