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v3.19.3.a.u2

Accounting Changes - Narrative (Details) - CAD ($) $ in Millions |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jan. 01, 2019 | Jun. 30, 2017 | Sep. 30, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2019
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Impact of change in accounting policy (Note 3) |  |  |  |  | $ 3 | $ (13) |
Right-of-use assets |  |  |  | $ 146 | 0 |  |
Property, plant and equipment |  |  |  | 6,207 | 6,164 | 6,578 |
Finance lease liabilities | $ 32 |  |  |  |  |  |
Depreciation and amortization |  |  |  | 590 | 574 | 635 |
Contract liabilities (Note 5) |  |  |  | 14 | 80 |  |
Deferred income tax liabilities (Note 11) |  |  |  | 472 | 501 |  |
Non-controlling interests (Note 12) |  |  |  | 1,101 | 1,137 |  |
Deficit |  |  |  | (1,455) | (1,496) |  |
Lease liabilities | 52 |  |  |  |  |  |
Non-cancellable operating leases | 83 |  |  | 77 | 80 |  |
Revisions in discount rates |  |  |  | 16 | (37) |  |
IFRS 16 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Right-of-use assets | 85 |  |  | 146 | 52 |  |
Property, plant and equipment |  |  |  |  | 38 |  |
Assets under finance leases | (29) |  |  |  |  |  |
Coal generation |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Property, plant and equipment |  |  |  | 2,120 | 2,172 | 2,457 |
Deficit |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Impact of change in accounting policy (Note 3) |  |  |  |  | 3 | (14) |
Change in Useful Lives Estimate | Sheerness |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  | (8) |  |  |
Change in Useful Lives Estimate | Coal generation |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  | 16 |  |  |
Change in Useful Lives Estimate | Wind and Solar |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  | 11 |  |  |
Decommissioning and restoration | Centralia Coal Mine |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Provision for decommissioning, restoration and rehabilitation costs |  |  |  | 222 |  |  | $ 141
Impairment loss |  |  |  | 141 |  |  |
Alberta Mine | Change in Useful Lives Estimate |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  |  | 38 | 58 |
Sundance Unit 1 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Impairment loss |  | $ 20 |  |  |  |  |
Sundance Unit 1 | Change in Useful Lives Estimate |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  |  |  | 26 |
Sundance Unit 2 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Impairment loss |  |  | $ 38 |  |  |  |
Sundance Unit 2 | Change in Useful Lives Estimate |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Depreciation and amortization |  |  |  |  |  | 4 |
IFRS 15 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
IFRS 16 and 15 transition adjustments(1) |  |  |  | 15 | 17 |  |
Contract liabilities (Note 5) |  |  |  | 15 | $ 88 | $ 62 |
IFRS 16 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Finance lease liabilities | 63 |  |  |  |  |  |
Expense relating to leases of low-value assets for which recognition exemption has been used |  |  |  | (1) |  |  |
Termination benefits expense |  |  |  | 4 |  |  |
Undiscounted operating lease payments to be received |  |  |  | $ 83 |  |  |
Revisions in discount rates | (31) |  |  |  |  |  |
Minimum | IFRS 16 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Lease liabilities | 42 |  |  |  |  |  |
Maximum | IFRS 16 |  |  |  |  |  |  |
Disclosure of changes in accounting estimates [line items] |  |  |  |  |  |  |
Lease liabilities | $ 52 |  |  |  |  |  |

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