CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 2,852	$ 2,444	$ 2,440
Net (loss) gain in foreign currency translation adjustments, net of hedging activities	(291)	18	37
Change in derivatives designated as cash flow hedges	48	10	12
Change in pension and post-retirement defined benefit plans	1,286	(407)	(661)
Equity accounted investments	9	(1)	(2)
Other comprehensive income (loss) before income taxes	1,052	(380)	(614)
Income tax (expense) recovery on above items	(341)	88	135
Other comprehensive income (loss)	711	(292)	(479)
Comprehensive income	$ 3,563	$ 2,152	$ 1,961