Revenue - Accounts Receivable (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Customers		$ 205	$ 239
Contract assets	[1]	29	18
Non-customers		4	12
Total Accounts Receivable	[2]	238	269
Firm Service Transportation [Member]
Disaggregation of Revenue [Line Items]
Contract assets		$ 8	$ 6

[1] Contract assets reflected in Total Accounts Receivable include accrued minimum volume commitments. Contract assets are primarily attributable to revenues associated with estimated shortfall volumes on certain annual minimum volume commitment arrangements. Total Accounts Receivable does not include contract assets related to firm service transportation contracts with tiered rates of $8 million as of June 30, 2020 and $6 million as of December 31, 2019, which are reflected in Other Assets.

[2] Total Accounts Receivable includes Accounts receivable, net of allowance for doubtful accounts and Accounts receivable—affiliated companies.