Commitments and Contingencies (Details)			1 Months Ended			2 Months Ended		26 Months Ended	29 Months Ended
	Jul. 10, 2015 bbl	Jan. 15, 2015 item	Jul. 31, 2015 item	May. 31, 2015 bbl	Feb. 28, 2013 bbl	Jun. 30, 2015 USD ($) item bbl	Jun. 30, 2013 item bbl	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jul. 14, 2015 USD ($)	May. 22, 2015 USD ($)	Apr. 30, 2015 item	Feb. 28, 2015 CAD	Dec. 31, 2014 USD ($)
Environmental
Estimated undiscounted reserve for environmental liabilities						$ 297,000,000		$ 297,000,000	$ 297,000,000					$ 82,000,000
Estimated undiscounted reserve for environmental liabilities, short-term						197,000,000		197,000,000	197,000,000					13,000,000
Estimated undiscounted reserve for environmental liabilities, long-term						100,000,000		100,000,000	100,000,000					69,000,000
Amounts probable of recovery under insurance and from third parties under indemnification agreements						200,000,000		200,000,000	200,000,000					$ 8,000,000
Line 901 Incident
Environmental
Aggregate total estimated costs						257,000,000		257,000,000	257,000,000
Estimated undiscounted reserve for environmental liabilities						221,000,000		221,000,000	221,000,000
Amounts probable of recovery under insurance and from third parties under indemnification agreements						$ 192,000,000		192,000,000	192,000,000
Amount of crude oil removed from pipeline (in barrels) | bbl						26,500
Charges, fines or penalties assessed						$ 0		0	0
Line 901 Incident | Civil or Criminal Charges
Environmental
Number of cases filed during the period | item						0
Line 901 Incident | Class Action Lawsuits
Environmental
Number of cases filed during the period | item						6
Line 901 Incident | Drain Down Methodology
Environmental
Estimated size of release, excluding potential incremental amount (in barrels) | bbl				2,400		2,400
Line 901 Incident | Alternative Purge Data
Environmental
Estimated size of release, potential incremental amount (in barrels) | bbl						1,000
MP 29 Release | Subsequent Event
Environmental
Estimated size of release (in barrels) | bbl	100
Charges, fines or penalties assessed										$ 0
MP 29 Release | Maximum | Subsequent Event
Environmental
Aggregate total estimated costs										$ 10,000,000
MP 29 Release | Class Action Lawsuits | Subsequent Event
Environmental
Number of cases filed during the period | item			1
Cushing Tank Cathodic Protection | PHMSA
Environmental
Charges, fines or penalties assessed											$ 102,900
In the Matter of Bakersfield Crude Terminal LLC et al
Environmental
Number of alleged rule violations | item												10
Charges, fines or penalties assessed						$ 0		0	0
Kemp River Pipeline Release
Environmental
Number of events occurred | item							2
Estimated size of release (in barrels) | bbl							700
Total estimated cost to clean up and remediate the site						15,000,000		15,000,000	15,000,000
Cost incurred, to date, to clean up and remediate the site								9,000,000
Bay Springs Pipeline Release
Environmental
Estimated size of release (in barrels) | bbl					120
Total cost to clean up and remediate the site									6,000,000
PMC | National Energy Board Audit
Environmental
Number of conditions imposed related to regulatory compliance | item		6
Charges, fines or penalties assessed | CAD													CAD 76,000
PMC | Kemp River Pipeline Release
Environmental
Charges, fines or penalties assessed						$ 0		$ 0	$ 0