Derivative and Hedging Activities - Marketing Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Revenues	$ 440	$ 1,179	$ 1,334	$ 2,409
Losses on undesignated marketing natural gas derivatives	(173)	275	734	(26)
Revenues	521	2,386	3,062	4,582
Marketing, Gathering and Compression | Other contract
Derivative [Line Items]
Losses on undesignated marketing natural gas derivatives	0	(1)	0	(3)
Marketing | Marketing, Gathering and Compression
Derivative [Line Items]
Revenues	240	917	964	2,152
Marketing
Derivative [Line Items]
Revenues	232	824	894	1,967
Losses on undesignated marketing natural gas derivatives		(1)		(3)
Revenues	$ 240	$ 916	$ 964	$ 2,149