Pension and Other Post-Retirement Benefit Obligations - Summary of Key Assumptions (Details) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Celgar | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Benefit obligation, Discount rate | 5.10% | 4.70% | 4.60% |
| Benefit obligations, Rate of compensation increase | 2.50% | 2.50% | 2.50% |
| Net benefit cost, Discount rate | 4.70% | 4.60% | 5.00% |
| Net benefit cost, Rate of compensation increase | 2.50% | 2.50% | 2.50% |
| Net benefit cost, Expected rate of return on plan assets | 5.50% | 5.45% | 5.45% |
| Peace River's | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Benefit obligation, Discount rate | 5.10% | 4.70% | 4.60% |
| Benefit obligations, Rate of compensation increase | 2.75% | 2.75% | 2.75% |
| Net benefit cost, Discount rate | 4.70% | 4.60% | 5.00% |
| Net benefit cost, Rate of compensation increase | 2.75% | 2.75% | 2.75% |
| Net benefit cost, Expected rate of return on plan assets | 6.23% | 6.18% | 6.18% |