General - Related Party Transactions (Details) - WES - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Summary of Significant Accounting Policies [Line Items]
Sales	$ 91	$ 119
Purchases
Summary of Significant Accounting Policies [Line Items]
Purchases	17	311
Transportation, gathering and other fees paid
Summary of Significant Accounting Policies [Line Items]
Purchases	$ 472	$ 546