Restructuring and Reorganization Costs - Additional Information (Details) $ in Millions	3 Months Ended
	Jun. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Before tax charge	$ 1,015
After tax charge	784
Operating Segments | Upstream | United States
Restructuring Cost and Reserve [Line Items]
Before tax charge	157
After tax charge	120
Operating Segments | Upstream | International
Restructuring Cost and Reserve [Line Items]
Before tax charge	376
After tax charge	296
Operating Segments | Downstream | United States
Restructuring Cost and Reserve [Line Items]
Before tax charge	109
After tax charge	82
Operating Segments | Downstream | International
Restructuring Cost and Reserve [Line Items]
Before tax charge	78
After tax charge	62
All Other
Restructuring Cost and Reserve [Line Items]
Before tax charge	295
After tax charge	224
Operating Expenses
Restructuring Cost and Reserve [Line Items]
Before tax charge	895
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Before tax charge	$ 120