Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 14, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Toll tax accrued	$ 16			$ 268
Discrete tax benefit	31	$ (12)
One-time Deemed Repatriation
Operating Loss Carryforwards [Line Items]
Tax benefit from foreign tax credits	$ 252
Installment period	8 years
Expense related to tax rate change adjustment	$ 107
Discrete tax benefit	$ 145
Tamar and Dalit Fields | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Operating Loss Carryforwards [Line Items]
Percentage of divestiture farmed out			7.50%