Discontinued operations - Narratives (Details) - MDA business - Discontinued operations $ in Millions, $ in Millions	Dec. 29, 2019 CAD ($)	Dec. 31, 2019 USD ($)
Discontinued Operations
Aggregate purchase price	$ 1,000
Purchase price adjustment	65
Reverse termination fee	$ 55
Transition Services, Period	12 months
Transition Services extension period	6 months
Accrued Liabilities
Discontinued Operations
Reserves for legal proceedings liabilities		$ 60