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Accumulated Other Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - CAD CAD in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | CAD 137 | CAD (348)
Other comprehensive income (loss) before reclassifications | 0 | 371
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 19 | (114)
Other equity method reclassification adjustment | (46) | 0
Net current period other comprehensive income (loss) | (27) | 485
Other | (4) | 0
Ending Balance | 106 | 137
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (35) | (8)
Other comprehensive income (loss) before reclassifications | 11 | (34)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 11 | (7)
Other equity method reclassification adjustment | (8) |
Net current period other comprehensive income (loss) | 14 | (27)
Other | 0 | 0
Ending Balance | (21) | (35)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (318) | (425)
Other comprehensive income (loss) before reclassifications | 0 | 0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 12 | (107)
Other equity method reclassification adjustment | (3) |
Net current period other comprehensive income (loss) | 9 | 107
Other | 0 | 0
Ending Balance | (309) | (318)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 0 | 0
Other comprehensive income (loss) before reclassifications | (49) | 0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 0 | 0
Other equity method reclassification adjustment | 0 |
Net current period other comprehensive income (loss) | (49) | 0
Other | 0 | 0
Ending Balance | (49) | 0
Accumulated Net Available For Sale Securities Gain (Loss) [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 0 | 3
Other comprehensive income (loss) before reclassifications | 3 | (3)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | (4) | 0
Other equity method reclassification adjustment | 0 |
Net current period other comprehensive income (loss) | (1) | (3)
Other | 0 | 0
Ending Balance | (1) | 0
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 490 | 82
Other comprehensive income (loss) before reclassifications | 35 | 408
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 0 | 0
Other equity method reclassification adjustment | (35) |
Net current period other comprehensive income (loss) | 0 | 408
Other | (4) | 0
Ending Balance | CAD 486 | CAD 490

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- Definition Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). + References No definition available. + Details
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