Derivative Instruments - Impact of Derivative Activities on Condensed Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives	$ (44,368)	$ 151,119
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	32	(6,683)
Gain (Loss) on Commodity Derivative Instruments	(44,400)	157,802
Cash Settlements Interest Rate Swap Operating Activities	(922)	68
Cash Settlements Commodity Operating Activities	(6,247)	(337)
Cash settlements and premiums received (paid), net	$ (7,169)	$ (269)