Segment Disclosures Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions	1 Months Ended			6 Months Ended
	Jun. 30, 2021		Feb. 28, 2021	Jun. 30, 2021		Jun. 30, 2020	Dec. 31, 2020
Segment assets:
Total assets	$ 45,507			$ 45,507			$ 44,165
Property, Plant and Equipment, Additions				693		$ 581
Transmission And Gulf Of Mexico [Member]
Segment assets:
Total assets	19,575			19,575			19,110
Northeast G And P [Member]
Segment assets:
Total assets	14,470			14,470			14,569
West [Member]
Segment assets:
Total assets	10,448			10,448			10,558
Other [Member]
Segment assets:
Total assets	2,570	[1]		2,570	[1]		927
Other [Member] | 2021 Wamsutter Field Acquisition
Segment assets:
Payments to Acquire Productive Assets	86		$ 79
Property, Plant and Equipment, Additions	257		290
Asset Retirement Obligation, Liabilities Incurred	125		$ 207
Increase (Decrease) in Accounts and Other Receivables	48
Intersegment Elimination [Member]
Segment assets:
Total assets	$ (1,556)			$ (1,556)			$ (999)

[1] The increase at our Other segment is primarily due to increased cash balance and the acquisitions of oil and gas properties in 2021. In February 2021, we acquired properties in the Wamsutter field in Wyoming from a supermajor oil and gas company for approximately $79 million, a portion of which was paid in the prior year. We recorded $290 million of property, plant, and equipment and $207 million of ARO related to this transaction. In June 2021, we acquired additional properties also in the Wamsutter field in Wyoming from an oil and gas company for approximately $86 million in cash, which is net of approximately $48 million reflecting the full settlement of outstanding receivables. We recorded $257 million of property, plant, and equipment and $125 million of ARO related to this transaction. Our oil and gas exploration and production activities are accounted for under the successful efforts method.