Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0000101778 (http://www.sec.gov/CIK)

Inventory Disclosure [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	December 31, (In millions) 2016   2015 Crude oil, natural gas and bitumen $ 31   $ 35 Supplies and other items 196   278 Inventories at cost $ 227   $ 313