Acquisitions and Divestitures - Business Combination, Recognized Asset Acquired and Liability Assumed (Details) - Encino - USD ($) $ in Millions	Aug. 01, 2025	Sep. 30, 2025
Business Combination [Line Items]
Total Consideration	$ 4,484
Fair Value of Assets Acquired:
Cash and Cash Equivalents	20
Accounts Receivable, Net	326
Inventories	12
Assets from Price Risk Management Activities	26
Other Current Assets	24
Oil and Gas Properties (Successful Efforts Method)	6,685
Other Property, Plant and Equipment	88
Other Assets	67
Amount Attributable to Assets Acquired	7,248
Fair Value of Liabilities Assumed:
Accounts Payable	632
Accrued Taxes Payable	17
Current Liabilities from Price Risk Management Activities	15
Current Portion of Operating Lease Liabilities	23
Other Current Liabilities	42
Senior Notes	1,266
Asset Retirement Obligations	52	$ 52
Other Liabilities	72
Deferred Income Taxes	645
Amount Attributable to Liabilities Assumed	2,764
Net Assets Acquired and Liabilities Assumed	$ 4,484