INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
UNRECOGNIZED TAX BENEFITS
Unrecognized tax benefits at beginning of year	$ 45	$ 55
Gross decreases for tax positions of prior year	(2)	(2)
Change in translation of foreign currency	4	(1)
Lapses of statute of limitations	(16)	(7)
Unrecognized tax benefits at end of year	$ 31	$ 45