Commitments and Contingencies (Details)			1 Months Ended	2 Months Ended		3 Months Ended	4 Months Ended	5 Months Ended	29 Months Ended	32 Months Ended
	Jul. 10, 2015 bbl	Jan. 15, 2015 item	Feb. 28, 2013 bbl	Jun. 30, 2015 bbl	Jun. 30, 2013 item bbl	Sep. 30, 2015 USD ($) item	Sep. 30, 2015 USD ($) bbl	Sep. 30, 2015 USD ($) item	Sep. 30, 2015 USD ($)	Sep. 30, 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						$ 197,000,000	$ 197,000,000	$ 197,000,000	$ 197,000,000	$ 197,000,000				$ 82,000,000
Estimated undiscounted reserve for environmental liabilities, short-term						96,000,000	96,000,000	96,000,000	96,000,000	96,000,000				13,000,000
Estimated undiscounted reserve for environmental liabilities, long-term						101,000,000	101,000,000	101,000,000	101,000,000	101,000,000				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	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	257,000,000	257,000,000
Estimated undiscounted reserve for environmental liabilities						126,000,000	126,000,000	126,000,000	126,000,000	126,000,000
Amounts probable of recovery under insurance and from third parties under indemnification agreements						192,000,000	192,000,000	192,000,000	192,000,000	192,000,000
Fines or penalties assessed						0	$ 0	$ 0	0	0
Line 901 Incident | Class Action Lawsuits
Environmental
Number of cases filed during the period | item								7
Line 901 Incident | Securities Law Class Action Lawsuits
Environmental
Number of cases filed during the period | item								2
Line 901 Incident | Initial Worst Case Estimate
Environmental
Estimated size of release (in barrels) | bbl				2,500
Line 901 Incident | Adjusted Worst Case Estimate
Environmental
Estimated size of release (in barrels) | bbl				2,400
Line 901 Incident | Worst Case Estimate, Alternative Methodology Purge Data | Maximum
Environmental
Estimated size of release (in barrels) | bbl							3,400
Line 901 Incident | Third Party Engineering and Consulting Firm, Preliminary Worst Case Estimate
Environmental
Estimated size of release (in barrels) | bbl							3,000
MP 29 Release
Environmental
Estimated size of release (in barrels) | bbl	100
Fines or penalties assessed						0	$ 0	$ 0	0	0
MP 29 Release | Maximum
Environmental
Aggregate total estimated costs						$ 10,000,000	10,000,000	10,000,000	10,000,000	10,000,000
MP 29 Release | Class Action Lawsuits
Environmental
Number of cases filed during the period | item						1
Cushing Tank Cathodic Protection | PHMSA
Environmental
Fines or penalties assessed											$ 102,900
In the Matter of Bakersfield Crude Terminal LLC et al
Environmental
Number of alleged rule violations | item												10
Fines or penalties assessed						$ 0	0	0	0	0
Kemp River Pipeline Release
Environmental
Number of events occurred | item					2
Estimated size of release (in barrels) | bbl					700
Total estimated costs to clean up and remediate the site						15,000,000	15,000,000	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
Fines or penalties assessed | CAD													CAD 76,000
PMC | Kemp River Pipeline Release
Environmental
Fines or penalties assessed						$ 0	$ 0	$ 0	$ 0	$ 0