Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
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Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 835
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-Section 45
-Paragraph 2
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Contractual interest rate for funds borrowed, under the debt agreement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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ACQUISITION OF COLUMBIA - Schedule of Fair Value of Debt Acquired (Details) CAD in Millions	Dec. 31, 2016	Jul. 01, 2016 USD ($)	Jul. 01, 2016 CAD
Senior Unsecured Notes, 2.45% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, face amount		$ 500,000,000
Senior Unsecured Notes, 3.30% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, face amount		750,000,000
Senior Unsecured Notes, 4.50% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, face amount		1,000,000,000
Senior Unsecured Notes, 5.80% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, face amount		500,000,000
Columbian Pipeline
Debt Instrument [Line Items]
Fair Value		2,981,000,000	CAD 3,878
Columbian Pipeline \| Senior Unsecured Notes
Debt Instrument [Line Items]
Fair Value		2,981,000,000
Columbian Pipeline \| Senior Unsecured Notes, 2.45% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Fair Value		506,000,000
Interest Rate	2.45%
Columbian Pipeline \| Senior Unsecured Notes, 3.30% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Fair Value		779,000,000
Interest Rate	3.30%
Columbian Pipeline \| Senior Unsecured Notes, 4.50% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Fair Value		1,092,000,000
Interest Rate	4.50%
Columbian Pipeline \| Senior Unsecured Notes, 5.80% Interest Rate \| Senior Unsecured Notes
Debt Instrument [Line Items]
Fair Value		$ 604,000,000
Interest Rate	5.80%