Fair Value Measurements (Assets and Liabilities Measured on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	$ 454,484	$ 285,105	$ 428,938
Provisionally priced contracts	10,116	(45,853)	7,500
Convertible preferred securities	16,803	11,618	13,550
Other assets and liabilities	19,420	(4,577)	(9,536)
Total	500,823	246,293	440,452
Level 1
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	235,665	128,407	38,627
Provisionally priced contracts	38,061	43,944	32,710
Convertible preferred securities	0	0	0
Other assets and liabilities	1,097	2,784	5,373
Total	274,823	175,135	76,710
Level 2
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	218,819	156,698	390,311
Provisionally priced contracts	(27,945)	(89,797)	(25,210)
Convertible preferred securities	0	0	0
Other assets and liabilities	18,323	(7,361)	(14,909)
Total	209,197	59,540	350,192
Level 3
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	0	0	0
Provisionally priced contracts	0	0	0
Convertible preferred securities	16,803	11,618	13,550
Other assets and liabilities	0	0	0
Total	$ 16,803	$ 11,618	$ 13,550