Components of Net Periodic Benefit Cost and Changes in Amounts Recorded in Accumulated Other Comprehensive Income (Detail) (CAD) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Current service cost	181	160	122
Interest cost	281	288	314
Expected return on plan assets	(331)	(288)	(308)
Amortization of prior service cost	23	23	21
Amortization of actuarial loss/(gain)	243	235	162
Net periodic benefit cost	397	418	311
Net actuarial loss/(gain)	(664)	530	1,112
Amortization of net actuarial (loss)/gain included in net periodic benefit cost	(243)	(235)	(162)
Prior service cost			86
Amortization of prior service cost included in net periodic benefit cost	(23)	(23)	(21)
Total recorded in other comprehensive income	(930)	272	1,015
Total recorded in net periodic benefit cost and other comprehensive income, before tax	(533)	690	1,326
Other post-retirement benefits
Defined Benefit Plan Disclosure [Line Items]
Current service cost	11	8	6
Interest cost	21	21	23
Amortization of actuarial loss/(gain)	10	8	3
Net periodic benefit cost	42	37	32
Net actuarial loss/(gain)	(50)	40	81
Amortization of net actuarial (loss)/gain included in net periodic benefit cost	(10)	(8)	(3)
Total recorded in other comprehensive income	(60)	32	78
Total recorded in net periodic benefit cost and other comprehensive income, before tax	(18)	69	110