Derivative Instruments - Effect of Derivative Instruments on the Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash received (paid) on settlement of derivative instruments, gain (loss) on derivative instruments	$ 14,106	$ 46,555	$ 33,529	$ 114,931
Non-cash gain (loss) on derivative instruments, gain (loss) on derivative instruments	(56,359)	(35,495)	(15,746)	(31,965)
Gain (loss) on derivative instruments	$ (42,253)	$ 11,060	$ 17,783	$ 82,966