advance billings and customer deposits - Reconciliation of contract liabilities (Details) - CAD ($) $ in Millions |
Jun. 30, 2019 |
Dec. 31, 2018 |
Jun. 30, 2018 |
|---|---|---|---|
| advance billings and customer deposits | |||
| Gross contract liabilities | $ 732 | $ 691 | |
| Reclassification to contract assets for contracts with contract liabilities less than contract assets | (155) | (142) | |
| Reclassification from contract assets for contracts with contract assets less than contract liabilities | (5) | (5) | |
| Current contract liabilities | $ 572 | $ 561 | $ 544 |