Income Taxes (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Net operating loss carry-forwards and tax credit carry-forwards
anticipated tax expense associated with the base-erosion and anti-abuse tax (“BEAT”) provision of the 2017 Tax Act	$ 0
Additional tax expense due to change in tax status	22
Additional deferred tax liabilities due to change in tax status	22
Tax expense on Federal blender’s credits recognized as revenue	4
One-time Federal blender's credits recognized as revenue	42
Maximum
Net operating loss carry-forwards and tax credit carry-forwards
Anticipated tax expense associated with the global intangible low-taxed income (“GILTI”) provision of the 2017 Tax Act	$ 1