Cash And Cash Equivalents Net Change in Operating Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019		Dec. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Accounts receivable	$ 1,653	$ (302)
Accounts receivable from related companies	(12)	(28)
Inventories	281	135
Other current assets	75	91
Other non-current assets, net	(94)	(34)
Accounts payable	(1,705)	323
Accounts payable to related companies	(73)	(69)
Accrued and other current liabilities	(185)	(409)
Other non-current liabilities	13	(31)
Derivative assets and liabilities, net	160	(13)
Net change in operating assets and liabilities, net of effects of acquisitions	$ 113	$ (337)	[1]	$ (405)	$ 62

[1] *As adjusted. See Note 1.