Schedule Of Measurement Of Lease Liabilities and Right Of Use Assets (Detail) - CAD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019
Cash paid for amounts included in the measurement of lease liabilities
Cash flows from operating activities, Operating leases	$ 37	$ 110
Cash flows from operating activities, Finance leases	11	33
Cash flows from financing activities, Finance leases	7	20
Non-cash right of use assets recorded for lease liabilities
For January 1 adoption of Leases	281	281	$ 298
In exchange for new lease liabilities during the period		90
Adoption of Leases Topic (842) [Member]
Non-cash right of use assets recorded for lease liabilities
For January 1 adoption of Leases	$ 298	$ 298