Derivative Instruments - Impact of Netting Agreements and Margin Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Asset derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	$ 1,053,502	$ 812,664
Liability derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	526,601	312,696
Commodity derivatives
Asset derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	1,053,502	812,664
Derivative instruments subject to master netting agreements	(315,171)	(226,116)
Margin requirements with counterparties	(20,044)	0
Net derivative instruments	718,287	586,548
Liability derivative instruments, at fair value
Gross derivative instruments recorded in the Condensed Consolidated Balance Sheets	526,601	312,696
Derivative instruments subject to master netting agreements	(315,171)	(226,116)
Margin requirements with counterparties	(1,077)	(12,606)
Net derivative instruments	$ 210,353	$ 73,974

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

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