Acquisitions and Divestitures (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquisitions and Divestitures [Line Items]
Acquisitions	$ 54	$ 210	$ 70
Divestitures	(736)	(1,262)	(1,908)
Net Acquisitions and Divestitures	(682)	(1,052)	(1,838)
Operating Segments [Member] \| Canadian Operations [Member]
Acquisitions and Divestitures [Line Items]
Acquisitions	31	1	9
Divestitures	(41)	(456)	(959)
Operating Segments [Member] \| USA Operations [Member]
Acquisitions and Divestitures [Line Items]
Acquisitions	23	209	27
Divestitures	$ (695)	$ (806)	(896)
Corporate, Non-segment [Member]
Acquisitions and Divestitures [Line Items]
Acquisitions			34
Divestitures			$ (53)

The cash outflow associated with the acquisition of proved and unproved property, plant, and equipment, and corporate properties.

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The net cash outflow or inflow from purchases, sales and disposals of property, plant and equipment and other productive assets, including intangibles.

+ References

No definition available.

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- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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