Interest Cost Components (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Amount charged to expense	$ 24	$ 338	$ 378	$ 496
Amount capitalized		33	23	22
Interest costs		$ 371	$ 401	$ 518