Schedule II - Valuation and Qualifying Accounts (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accruals for personal injury and other claims provision
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	$ 126	$ 141	$ 152
Additions charged to expenses	114	105	142
Payments and other reductions	(117)	(119)	(152)
Impact of FX	0	(1)	(1)
Ending balance at December 31	123	126	141
Environmental liabilities
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	80	77	82
Additions charged to expenses	10	10	6
Payments and other reductions	(10)	(6)	(8)
Impact of FX	(1)	(1)	(3)
Ending balance at December 31	$ 79	$ 80	$ 77