INTERIM CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 602	$ 409
Net gain (loss) in foreign currency translation adjustments, net of hedging activities	10	(65)
Change in derivatives designated as cash flow hedges	25	2
Change in pension and post-retirement defined benefit plans	53	45
Other comprehensive income (loss) before income taxes	88	(18)
Income tax (expense) recovery on above items	(30)	60
Other comprehensive income	58	42
Comprehensive income	$ 660	$ 451