INTERIM CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 409	$ 434
Net (loss) gain in foreign currency translation adjustments, net of hedging activities	(65)	16
Change in derivatives designated as cash flow hedges	2	2
Change in pension and post-retirement defined benefit plans	45	20
Other comprehensive (loss) income before income taxes	(18)	38
Income tax recovery (expense) on above items	60	(22)
Other comprehensive income (loss)	42	16
Comprehensive income	$ 451	$ 450