Revenue (Narrative) (Details) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020 USD ($) item	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) item	Sep. 30, 2019 USD ($)	Sep. 09, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Customer deposits/ deferred revenue	$ 1,300			$ 1,300			$ 1,000
Deferred revenue current	181			181			104
Deferred revenue non-current	1,153			1,153			927
Increase (decrease) in customer deposits				$ (107)	$ (37)
Long-term supply commitment				10 years
Revenue	3,001		$ 2,934	$ 7,953	$ 8,686
Other assets	1,474			1,474			1,487
Deferred revenue						$ 1,070
Cumulative adjustment related to customer contract		$ 105		(105)
Other Noncurrent Liabilities [Member]
Customer deposits/ deferred revenue	1,153			1,153			927
Other Current Liabilities [Member]
Customer deposits/ deferred revenue	181			181			104
Accounting Standards Update 2014-09 [Member]
Other assets							$ 212
HSG [Member]
Customer deposits/ deferred revenue	264			264
Deferred revenue current	132			132
Deferred revenue non-current	931			931
Deferred revenue	$ 1,070			$ 1,070
HSG [Member] | Minimum [Member]
Year	2029			2029
HSG [Member] | Maximum [Member]
Year	2034			2034
Revenue Adjustments [Member]
Cumulative adjustment related to customer contract				$ 105
Measurement Input, Discount Rate [Member] | HSG [Member] | Minimum [Member]
Measurement input | item	0.0254			0.0254
Measurement Input, Discount Rate [Member] | HSG [Member] | Maximum [Member]
Measurement input | item	0.0323			0.0323
HSG [Member]
Customer deposits/ deferred revenue						$ 264
HSG [Member] | Measurement Input, Discount Rate [Member]
Measurement input | item	0.165			0.165
HSG [Member] | Measurement Input, Discount Rate [Member] | Minimum [Member]
Measurement input | item						0.0254
HSG [Member] | Measurement Input, Discount Rate [Member] | Maximum [Member]
Measurement input | item						0.0323
HSG [Member] | Measurement Input, Long-term Revenue Growth Rate [Member]
Measurement input | item	0			0