v3.8.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Feb. 14, 2018
Jun. 30, 2017
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Trading Symbol UAL    
Entity Registrant Name United Continental Holdings, Inc.    
Entity Central Index Key 0000100517    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   284,700,547  
Entity Public Float     $ 21,673,390,018
United Airlines, Inc.      
Document Information [Line Items]      
Entity Registrant Name United Airlines, Inc.    
Entity Central Index Key 0000319687    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Common Stock, Shares Outstanding   1,000