Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Supplemental Cash Flow Information [Abstract]
Cash paid during the period for interest on debt, net of amounts capitalized	$ 211	$ 295
Cash paid for income taxes, net of refunds	0	1
Balance in property, plant and equipment, net funded with accounts payable and accrued liabilities	$ 360	$ 255