Derivative Instruments - Impact of Netting Agreements and Margin Deposits (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Asset derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	$ 648,855	$ 527,073
Liability derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	2,160,253	600,877
Commodity derivatives
Asset derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	648,855	527,073
Derivative instruments subject to master netting agreements	(576,429)	(328,809)
Margin requirements with counterparties	0	0
Net derivative instruments	72,426	198,264
Liability derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	2,160,253	600,877
Derivative instruments subject to master netting agreements	(576,429)	(328,809)
Margin requirements with counterparties	(490,109)	(82,552)
Net derivative instruments	$ 1,093,715	$ 189,516

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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