Condensed Consolidating Financial Information - Interim Condensed Consolidating Statements of Income (Details) - CAD CAD in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues
Freight	CAD 1,563	CAD 1,548
Non-freight	40	43
Total revenues	1,603	1,591
Operating expenses
Compensation and benefits	233	329
Fuel	170	125
Materials	49	56
Equipment rents	36	45
Depreciation and amortization	166	162
Purchased services and other	278	221
Total operating expenses	932	938
Operating income	671	653
Less:
Other income and charges	(28)	(181)
Net interest (income) expense	120	124
Income before income tax expense	579	710
Less: Income tax (recovery) expense	148	170
Add: Equity in net earnings of subsidiaries	0	0
Net income	431	540
Consolidating Adjustments and Eliminations [Member]
Revenues
Freight	0	0
Non-freight	(85)	(86)
Total revenues	(85)	(86)
Operating expenses
Compensation and benefits	1	2
Fuel	0	0
Materials	6	8
Equipment rents	0	0
Depreciation and amortization	0	0
Purchased services and other	(92)	(96)
Total operating expenses	(85)	(86)
Operating income	0	0
Less:
Other income and charges	0	0
Net interest (income) expense	0	0
Income before income tax expense	0	0
Less: Income tax (recovery) expense	0	0
Add: Equity in net earnings of subsidiaries	(566)	(571)
Net income	(566)	(571)
CPRL (Parent Guarantor) [Member] | Reportable Legal Entities [Member]
Revenues
Freight	0	0
Non-freight	0	0
Total revenues	0	0
Operating expenses
Compensation and benefits	0	0
Fuel	0	0
Materials	0	0
Equipment rents	0	0
Depreciation and amortization	0	0
Purchased services and other	0	0
Total operating expenses	0	0
Operating income	0	0
Less:
Other income and charges	(20)	(69)
Net interest (income) expense	2	(1)
Income before income tax expense	18	70
Less: Income tax (recovery) expense	1	9
Add: Equity in net earnings of subsidiaries	414	479
Net income	431	540
CPRC (Subsidiary Issuer) [Member] | Reportable Legal Entities [Member]
Revenues
Freight	1,089	1,097
Non-freight	32	33
Total revenues	1,121	1,130
Operating expenses
Compensation and benefits	124	201
Fuel	132	103
Materials	34	38
Equipment rents	36	54
Depreciation and amortization	109	107
Purchased services and other	208	136
Total operating expenses	643	639
Operating income	478	491
Less:
Other income and charges	(7)	(138)
Net interest (income) expense	125	131
Income before income tax expense	360	498
Less: Income tax (recovery) expense	98	111
Add: Equity in net earnings of subsidiaries	152	92
Net income	414	479
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Revenues
Freight	474	451
Non-freight	93	96
Total revenues	567	547
Operating expenses
Compensation and benefits	108	126
Fuel	38	22
Materials	9	10
Equipment rents	0	(9)
Depreciation and amortization	57	55
Purchased services and other	162	181
Total operating expenses	374	385
Operating income	193	162
Less:
Other income and charges	(1)	26
Net interest (income) expense	(7)	(6)
Income before income tax expense	201	142
Less: Income tax (recovery) expense	49	50
Add: Equity in net earnings of subsidiaries	0	0
Net income	CAD 152	CAD 92