Asset Acquisitions and Dispositions (Net Assets Acquired) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Jan. 15, 2021	Dec. 31, 2020
Assets Acquired
Investments and long-term receivables	$ 7,113		$ 8,017
Concho Resources Incorporated [Member]
Assets Acquired
Cash and cash equivalents		$ 382
Accounts receivable, net		745
Inventories		45
Prepaid expenses and other current assets		37
Investments and long-term receivables		333
Net properties, plants and equipment		18,923
Other assets		62
Total assets acquired		20,527
Liabilities Assumed
Accounts Payable		638
Accrued income and other taxes		56
Employee benefit obligations		4
Other accruals		510
Long-term debt		4,696
Asset retirement obligations and accrued environmental costs		310
Deferred income taxes		1,071
Other liabilities and deferred credits		117
Total Liabilities assumed		7,402
Net assets acquired		$ 13,125
Shell Permian Assets [Member]
Assets Acquired
Cash and cash equivalents	337
Accounts receivable, net	20
Net properties, plants and equipment	8,624
Other assets	50
Total assets acquired	9,031
Liabilities Assumed
Accounts Payable	211
Accrued income and other taxes	6
Other accruals	20
Asset retirement obligations and accrued environmental costs	86
Other liabilities and deferred credits	36
Total Liabilities assumed	359
Net assets acquired	$ 8,672