COMMITMENTS, CONTINGENCIES AND GUARANTEES - Contingencies (Details) $ in Millions	Dec. 31, 2019 CAD ($)
COMMITMENTS, CONTINGENCIES AND GUARANTEES
Maximum potential amount payable under indemnification agreements	$ 125

The maximum potential amount payable under indemnification agreements.

No definition available.

Name:	su_MaximumPotentialAmountPayableUnderIndemnificationAgreements
Namespace Prefix:	su_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant