v2.4.1.9
Document and Entity Information (USD $)
In Billions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Jan. 30, 2015
Jun. 30, 2014
Document and Entity Information [Abstract]      
Document type 10-K    
Document period end date Dec. 31, 2014    
Amendment flag false    
Entity registrant name UNION PACIFIC CORPORATION    
Entity central index key 0000100885    
Entity current reporting status Yes    
Entity voluntary filers No    
Current fiscal year end date --12-31    
Entity filer category Large Accelerated Filer    
Entity well known seasoned issuer Yes    
Entity common stock shares outstanding   881,284,029dei_EntityCommonStockSharesOutstanding  
Entity public float     $ 89.4dei_EntityPublicFloat
Document fiscal year focus 2014    
Document fiscal period focus FY