INTERIM CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 622	$ 510	$ 1,406	$ 1,421
Net gain (loss) in foreign currency translation adjustments, net of hedging activities	12	19	(24)	38
Change in derivatives designated as cash flow hedges	1	2	36	11
Change in pension and post-retirement defined benefit plans	28	38	86	113
Other comprehensive income (loss) before income taxes	41	59	98	162
Income tax recovery (expense) on above items	(22)	(34)	(11)	(78)
Other comprehensive income (loss)	19	25	87	84
Comprehensive income	$ 641	$ 535	$ 1,493	$ 1,505