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Interest Expense, Net (Details) CAD in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jun. 30, 2016 CAD | Dec. 31, 2016 CAD | Jun. 30, 2016 CAD | Dec. 31, 2016 CAD | Dec. 31, 2015 CAD
Debt Instrument [Line Items] |  |  |  |  |
Interest on debt |  |  |  | CAD 443 | CAD 193
Beneficial Conversion Feature |  |  |  | (43) | 0
Allowance for Funds Used During Construction |  |  |  | (13) | (4)
Interest Revenue |  |  |  | (2) | (6)
Other |  |  |  | 19 | 6
Interest Expense (Income), Net |  |  |  | 585 | 212
Interest Expense, Long-term Debt, Additional Information [Abstract] |  |  |  |  |
Amortization of Debt Discount (Premium) | CAD 62 |  |  |  |
Amortization Of Debt Discount (Premium) After Tax | CAD 43 |  |  |  |
Debt Instrument Convertible Converted Percent | 0.995 |  |  |  |
Revolving Credit Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest on debt |  |  |  | 11 | 0
Convertible Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest on debt |  |  |  | 65 | 23
Interest Expense, Long-term Debt, Additional Information [Abstract] |  |  |  |  |
Beneficial conversion feature, Interest Expense |  | CAD 62 |  | CAD 62 |
Convertible Subordinated Debt |  |  |  |  | CAD 2,185
Interest Expense, Junior Subordinated Debentures |  |  | CAD 21 |  |

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- Definition Amount of noncash expense after tax included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense. + References No definition available. + Details
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- Definition The amount of interest expense recognized associated to the benfecial conversion feature. + References No definition available. + Details
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- Definition Percent of debntures converted during the period. + References No definition available. + Details
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- Definition Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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- Definition Including the current and noncurrent portions, the carrying value of convertible subordinated debt, as of the balance sheet date, initially scheduled to be repaid after one year or beyond the normal operating cycle if longer. This form of debt can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder, and places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Amount of a favorable spread to a debt holder between the amount of debt being converted and the value of the securities received upon conversion. This is an embedded conversion feature of convertible debt issued that is in-the-money at the commitment date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Beneficial Conversion Feature -URI http://asc.fasb.org/extlink&oid=6505963 + 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. + Details
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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- Definition Interest expense incurred during the reporting period on junior subordinated debentures. Includes amortization of expenses incurred in the issuance of subordinated notes and debentures. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.8) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition Amount of interest expense classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4D -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624177-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph -4 -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition The net amount of operating interest income (expense). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.10) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition Amount of interest income earned from interest bearing assets classified as other. + References No definition available. + Details
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- Definition Amount capitalized of allowance for funds used during construction. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501662&loc=d3e56162-110433 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Allowance for Funds Used during Construction -URI http://asc.fasb.org/extlink&oid=6504829 + Details
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