CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - CAD ($) $ in Millions	Total	Share capital	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings
Beginning balance at Dec. 31, 2016	$ 4,626	$ 2,002	$ 52	$ (1,799)	$ 4,371
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,405	0	0	0	2,405
Other comprehensive (loss) income	58	0	0	58	0
Dividends declared	(319)	0	0	0	(319)
Effect of stock-based compensation expense	3	0	3	0	0
CP Common Shares repurchased	(381)	(27)	0	0	(354)
Shares issued under stock option plan	45	57	(12)	0	0
Ending balance at Dec. 31, 2017	6,437	2,032	43	(1,741)	6,103
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,951	0	0	0	1,951
Other comprehensive (loss) income	(302)	0	0	(302)	0
Dividends declared	(358)	0	0	0	(358)
Effect of stock-based compensation expense	11	0	11	0	0
CP Common Shares repurchased	(1,127)	(66)	0	0	(1,061)
Shares issued under stock option plan	24	36	(12)	0	0
Ending balance at Dec. 31, 2018	6,636	2,002	42	(2,043)	6,635
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,440	0	0	0	2,440
Other comprehensive (loss) income	(479)	0	0	(479)	0
Dividends declared	(434)	0	0	0	(434)
Effect of stock-based compensation expense	15	0	15	0	0
CP Common Shares repurchased	(1,140)	(54)	0	0	(1,086)
Shares issued under stock option plan	36	45	(9)	0	0
Ending balance at Dec. 31, 2019	$ 7,069	$ 1,993	$ 48	$ (2,522)	$ 7,550