REVENUE - Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2022 CAD ($)	Jun. 30, 2022 CAD ($)
Revenue from Contract with Customer [Abstract]
Revenue recognized	$ 21	$ 82
Increase in contract with customers, liability	131	228
Remaining performance obligation	58,300	58,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 3,700	$ 3,700
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, period	6 months	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 6,300	$ 6,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, period	1 year	1 year