Financial Instruments - Credit Losses (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 01, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Equity		$ (134,386)	$ (144,914)	$ (145,208)	$ (157,451)	$ (156,118)	$ (155,642)
Related Party Transaction [Line Items]
Allowance for credit loss		528		849
Trade receivable		7,100
Additional allowance		9
Non-trade receivable		2,800
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Equity		(166,122)	$ (176,113)	$ (174,945)	$ (183,442)	$ (181,387)	$ (180,987)
Investments and Advances
Related Party Transaction [Line Items]
Allowance for credit loss		560
Government Joint Venture Partners
Related Party Transaction [Line Items]
Allowance for credit loss		140
Reduction in allowance for credit losses		$ 550
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Equity	$ 25