v3.25.4
Cover
 12 Months Ended
Dec. 31, 2025
shares
Document Information [Line Items]  
Document Type 40-F
Amendment Flag false
Document Registration Statement false
Document Annual Report true
Document Period End Date Dec. 31, 2025
Document Fiscal Period Focus FY
Document Fiscal Year Focus 2025
Current Fiscal Year End Date --12-31
Entity File Number 1-2413
Entity Registrant Name CANADIAN NATIONAL RAILWAY COMPANY
Entity Central Index Key 0000016868
Entity Primary SIC Number 4011
Entity Tax Identification Number 98-0018609
Entity Incorporation, State or Country Code Z4
Entity Address, Address Line One 935 de La Gauchetiere Street West
Entity Address, City or Town Montreal
Entity Address, State or Province QC
Entity Address, Country CA
Entity Address, Postal Zip Code H3B 2M9
City Area Code 514
Local Phone Number 399-7091
Title of 12(b) Security Common shares
Trading Symbol CNI
Security Exchange Name NYSE
Annual Information Form true
Audited Annual Financial Statements false
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Emerging Growth Company false
Entity Common Stock, Shares Outstanding 614,433,951
ICFR Auditor Attestation Flag true
Auditor Name KPMG LLP
Auditor Location Montreal, Quebec, Canada
Auditor Firm ID 85
Business Contact [Member]  
Document Information [Line Items]  
Entity Address, Address Line One 28 Liberty Street
Entity Address, City or Town New York
Entity Address, State or Province NY
Entity Address, Postal Zip Code 10005
City Area Code 212
Local Phone Number 894-8940
Contact Personnel Name C T Corporation System