General - Related Party Transactions (Details) - WES - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Summary of Significant Accounting Policies [Line Items]
Sales	$ 111	$ 165
Purchases
Summary of Significant Accounting Policies [Line Items]
Purchases	17	474
Transportation, gathering and other fees paid
Summary of Significant Accounting Policies [Line Items]
Purchases	$ 717	$ 804