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
Supplemental Cash Flow Elements [Abstract]
Accounts receivable	$ 1,667	$ (302)
Accounts receivable from related companies	(20)	(38)
Inventories	281	135
Other current assets	110	99
Other non-current assets, net	(101)	(34)
Accounts payable	(1,704)	321
Accounts payable to related companies	(21)	(10)
Accrued and other current liabilities	(233)	(406)
Other non-current liabilities	25	(31)
Derivative assets and liabilities, net	160	(13)
Net change in operating assets and liabilities, net of effects of acquisitions	$ (164)	$ 279	$ 444	$ (234)