CONSOLIDATED STATEMENTS OF INCOME - CAD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Total revenues	$ 2,069	$ 1,979	$ 1,977	$ 1,767	$ 2,006	$ 1,898	$ 1,750	$ 1,662	$ 7,792	$ 7,316	$ 6,554
Operating expenses
Compensation and benefits									1,540	1,468	1,309
Fuel									882	918	677
Materials									210	201	190
Equipment rents									137	130	142
Depreciation and amortization									706	696	661
Purchased services and other									1,193	1,072	1,056
Total operating expenses									4,668	4,485	4,035
Operating income	890	869	822	543	874	790	627	540	3,124	2,831	2,519
Less:
Other (income) expense									(89)	174	(178)
Other components of net periodic benefit recovery									(381)	(384)	(274)
Net interest expense									448	453	473
Income before income tax expense									3,146	2,588	2,498
Income tax expense									706	637	93
Net income	$ 664	$ 618	$ 724	$ 434	$ 545	$ 622	$ 436	$ 348	$ 2,440	$ 1,951	$ 2,405
Earnings per share
Basic earnings per share	$ 4.84	$ 4.47	$ 5.19	$ 3.10	$ 3.84	$ 4.36	$ 3.05	$ 2.41	$ 17.58	$ 13.65	$ 16.49
Diluted earnings per share	$ 4.82	$ 4.46	$ 5.17	$ 3.09	$ 3.83	$ 4.35	$ 3.04	$ 2.41	$ 17.52	$ 13.61	$ 16.44
Weighted-average number of shares (millions)
Basic									138.8	142.9	145.9
Diluted									139.3	143.3	146.3
Freight
Revenues
Total revenues									$ 7,613	$ 7,152	$ 6,375
Non-freight
Revenues
Total revenues									$ 179	$ 164	$ 179