financial instruments - Credit risk (Details) - CAD ($) $ in Millions |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Credit risk | ||
| Maximum exposure (excluding income tax effects) to credit risk | $ 3,345 | $ 3,435 |
| Cash and temporary investments, net | ||
| Credit risk | ||
| Maximum exposure (excluding income tax effects) to credit risk | 217 | 414 |
| Customer accounts receivable | ||
| Credit risk | ||
| Maximum exposure (excluding income tax effects) to credit risk | 1,835 | 1,600 |
| Contract assets | ||
| Credit risk | ||
| Maximum exposure (excluding income tax effects) to credit risk | 1,281 | 1,318 |
| Derivatives | ||
| Credit risk | ||
| Maximum exposure (excluding income tax effects) to credit risk | $ 12 | $ 103 |