Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	$ 13,093	$ 75,506
Derivative liabilities	44,328	85,106
Derivative Asset, Noncurrent	5,269	25,449
Derivative Liability, Noncurrent	14,914	28,434
Derivative Liability	59,242	113,540
Derivative Asset	18,362	100,955
Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative Liability	36,500
Commodity contracts \| Current Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	13,093	75,506
Derivative liabilities	40,598	81,451
Commodity contracts \| Noncurrent Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Noncurrent	5,269	25,449
Derivative Liability, Noncurrent	14,299	26,789
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability	4,300
Interest Rate Swap \| Current Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	0	0
Derivative liabilities	3,730	3,655
Interest Rate Swap \| Noncurrent Derivative Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Noncurrent	0	0
Derivative Liability, Noncurrent	615	1,645
Fair Value, Measurements, Recurring \| Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	13,093	75,506
Derivative liabilities	40,598	(81,451)
Derivative Asset, Noncurrent	5,269	25,449
Derivative Liability, Noncurrent	14,299	$ 26,789
Fair Value, Measurements, Recurring \| Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative liabilities	3,730
Derivative Liability, Noncurrent	$ 615

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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