Supplemental Information on Oil and Gas Producing Activities (Unaudited) - Proved reserves (Details)	12 Months Ended
	Dec. 31, 2023 Bcfe Bcf MMBbls MMcf	Dec. 31, 2022 Bcfe MMBbls Bcf MMcf	Dec. 31, 2021 Bcfe Bcf MMBbls
Proved developed and undeveloped reserves:
Balance at the beginning of the period | Bcfe	17,759	17,729	17,635
Revisions | Bcfe	1,187	596	1,486
Extensions, discoveries and other additions | Bcfe	413	604	472
Production | Bcfe	(1,238)	(1,170)	(1,194)
Sales | Bcfe			(670)
Balance at the end of the period | Bcfe	18,121	17,759	17,729
Oil and Gas Reserves
Proved developed reserves | Bcfe	13,783	13,373	12,753
Proved undeveloped reserves | Bcfe	4,338	4,386	4,976
VIE, Martica
Proved developed and undeveloped reserves:
Balance at the beginning of the period | Bcf		167
Balance at the end of the period | Bcf			167
Balance at the beginning of the period | Bcfe	92
Balance at the end of the period | Bcfe	75	92
Oil and Gas Reserves
Proved developed reserves | Bcfe	75	91	133
Proved undeveloped reserves | Bcfe	0		34
Natural gas
Proved developed and undeveloped reserves:
Balance at the beginning of the period | Bcf	10,270	10,204	10,025
Revisions | Bcf	863	427	993
Extensions, discoveries and other additions | Bcf	296	437	349
Production | Bcf	(815)	(798)	(826)
Sales | Bcf			(337)
Balance at the end of the period | Bcf	10,614	10,270	10,204
Oil and Gas Reserves
Proved developed reserves | Bcf	7,912	7,699	7,395
Proved undeveloped reserves | Bcf	2,702	2,571	2,809
Natural gas | VIE, Martica
Proved developed and undeveloped reserves:
Balance at the beginning of the period | Bcf	71	101
Balance at the end of the period | Bcf	58	71	101
Oil and Gas Reserves
Proved undeveloped reserves | Bcfe		1
Proved developed reserves | Bcf	58	70	78
Proved undeveloped reserves | Bcf			23
NGLS
Proved developed and undeveloped reserves:
Balance at the beginning of the period	1,217	1,219	1,236
Revisions	54	32	77
Extensions, discoveries and other additions	18	25	18
Production	(67)	(59)	(58)
Sales			(54)
Balance at the end of the period	1,222	1,217	1,219
Oil and Gas Reserves
Proved developed reserves	963	930	876
Proved undeveloped reserves	259	287	343
NGLS | VIE, Martica
Proved developed and undeveloped reserves:
Balance at the beginning of the period	3	11
Balance at the end of the period	3	3	11
Oil and Gas Reserves
Proved developed reserves	3	3	9
Proved undeveloped reserves			2
Oil and condensate
Proved developed and undeveloped reserves:
Balance at the beginning of the period	31	36	33
Revisions		(4)	6
Extensions, discoveries and other additions	2	2	2
Production	(4)	(3)	(4)
Sales			(1)
Balance at the end of the period	29	31	36
Oil and Gas Reserves
Proved developed reserves	15	16	17
Proved undeveloped reserves	14	15	19
Oil and condensate | VIE, Martica
Proved developed and undeveloped reserves:
Balance at the beginning of the period	0.2	0.4
Balance at the end of the period	0.1	0.2	0.4
Oil and Gas Reserves
Proved developed reserves	0.1	0.2	0.2
Proved undeveloped reserves			0.2