v2.4.0.6
Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Feb. 22, 2013
Jun. 29, 2012
Document and Entity Information      
Entity Registrant Name CoreSite Realty Corp    
Entity Central Index Key 0001490892    
Document Type 10-K    
Document Period End Date Dec. 31, 2012    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 360.9
Entity Common Stock, Shares Outstanding   21,202,610  
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY