Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Loss Carryforwards [Line Items]
Tax benefit from Tax Reform Legislation and Toll Tax	$ 145
Tamar and Dalit Fields | Disposed by sale
Operating Loss Carryforwards [Line Items]
Percentage of divestiture farmed out		7.50%