Fair Value Measurements (Assets and Liabilities Measured on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	$ 563,597	$ 285,105	$ 231,315
Provisionally priced contracts	4,807	(45,853)	(17,371)
Convertible preferred securities	15,905	11,618	11,649
Other assets and liabilities	14,109	(4,577)	(6,627)
Total	598,418	246,293	218,966
Level 1
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	264,806	128,407	19,145
Provisionally priced contracts	47,505	43,944	14,231
Convertible preferred securities	0	0	0
Other assets and liabilities	4,677	2,784	6,147
Total	316,988	175,135	39,523
Level 2
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	298,791	156,698	212,170
Provisionally priced contracts	(42,698)	(89,797)	(31,602)
Convertible preferred securities	0	0	0
Other assets and liabilities	9,432	(7,361)	(12,774)
Total	265,525	59,540	167,794
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	15,905	11,618	11,649
Other assets and liabilities	0	0	0
Total	$ 15,905	$ 11,618	$ 11,649