Equity Method Investments (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2019		Jun. 30, 2018
Contribution of net assets to Capline LLC		$ 143	[1]	$ 0
Recognition of Capline LLC equity method investment		$ 350	[1]	$ 0
Capline
Undivided joint interest, ownership percentage		33.00%
Equity method investments, ownership percentage		33.00%
Contribution of net assets to Capline LLC	[1]	$ 143
Recognition of Capline LLC equity method investment	[1]	350
Capline restructuring gain	[1]	$ 207

[1] See Note 13.