Debt and Credit Facilities Available Credit Facilities and Restrictive Debt Covenants (Details) CAD in Millions, $ in Millions		9 Months Ended
		Sep. 30, 2016 CAD	Sep. 30, 2016 USD ($)		Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity			$ 6,338
Commercial Paper Outstanding			1,637		$ 1,112
Available Credit Facilities Capacity			4,701
Spectra Energy Partners, LP
Line of Credit Facility [Line Items]
Line Of Credit Facility Maturity Year	[1]	2021
Total Credit Facilities Capacity	[1]		2,500
Commercial Paper Outstanding	[1]		1,177
Available Credit Facilities Capacity	[1]		1,323
Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Line Of Credit Facility Maturity Year	[2]	2021
Total Credit Facilities Capacity		CAD 400	305	[2]
Commercial Paper Outstanding	[2]		0
Available Credit Facilities Capacity	[2]		305
Union Gas Limited
Line of Credit Facility [Line Items]
Line Of Credit Facility Maturity Year	[3]	2021
Total Credit Facilities Capacity		CAD 700	533	[3]
Commercial Paper Outstanding	[3]		0
Available Credit Facilities Capacity	[3]		533
Multi Year Syndicated | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Line Of Credit Facility Maturity Year	[4]	2021
Total Credit Facilities Capacity	[4]		1,000
Commercial Paper Outstanding	[4]		460
Available Credit Facilities Capacity	[4]		540
364-day syndicated | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Line Of Credit Facility Maturity Year	[4]	2017
Total Credit Facilities Capacity	[4]		2,000
Commercial Paper Outstanding	[4]		0
Available Credit Facilities Capacity	[4]		$ 2,000

[1] Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of September 30, 2016, this ratio was 3.7 to 1.

[2] U.S. dollar equivalent at September 30, 2016. The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75%. The ratio was 31.1% at September 30, 2016.

[3] U.S. dollar equivalent at September 30, 2016. The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 68.1% at September 30, 2016.

[4] Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65%. Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 55.8% at September 30, 2016.