Prepaid Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Prepaid Expenses [Line Items]
Prepaid taxes	$ 26	$ 30
Prepaid insurance	6	8
Other prepaid expenses	11	5
Deposits		65
Total	$ 43	108
Statoil Property Acquisition [Member]
Prepaid Expenses [Line Items]
Deposits		50
WPX Property Acquisition [Member]
Prepaid Expenses [Line Items]
Deposits		$ 15