Derivative Instruments - Effect of Derivative Instruments on the Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash received (paid) on settlement of derivative instruments, gain (loss) on derivative instruments	$ 19,423	$ 15,397	$ 19,423	$ 68,377
Non-cash gain (loss) on derivative instruments, gain (loss) on derivative instruments	24,551	48,252	40,613	3,529
Gain (loss) on derivative instruments	$ 43,974	$ 63,649	$ 60,036	$ 71,906