Derivative Instruments - Gains (Losses) on Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives, net	$ 18,904	$ 8,121	$ 25,928	$ (16,466)
Total current period settlements on derivatives	795	9,964	(390)	26,572
Non-trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives, net	18,898	7,964	25,952	(16,569)
Total current period settlements on derivatives	795	10,055	(394)	26,664
Trading | Various acquisitions
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives				(300)
Non-cash Flow Hedging | Trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives, net	6	157	(24)	103
Total current period settlements on derivatives	$ 0	$ (91)	$ 4	$ (92)