RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Restricted Long-Term Investments (Details) - CAD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Long-Lived Assets Held-for-sale [Line Items] | ||
| Purchase of restricted long-term investments | $ 402.0 | $ 1.1 |
| Sale of restricted long-term investments | $ 256.0 | $ 995.0 |
| X | ||||||||||
- 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. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition The cash outflow to acquire investments (not to include restricted cash) that are pledged or subject to withdrawal restrictions. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition The cash inflow associated with the sale of investments that are pledged or subject to withdrawal restrictions during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|