v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Jul. 31, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 000-51829  
Entity Registrant Name COGENT COMMUNICATIONS HOLDINGS, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 46-5706863  
Entity Address, Address Line One 2450 N Street N.W.  
Entity Address, City or Town Washington, D.C  
Entity Address, Country US  
Entity Address, Postal Zip Code 20037  
Country Region 202  
City Area Code 295  
Local Phone Number 4200  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol CCOI  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   51,215,736
Entity Central Index Key 0001158324  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false