Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 13, 2018
Document Information [Line Items]
Entity Registrant Name	United Continental Holdings, Inc.
Entity Central Index Key	0000100517
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Trading Symbol	UAL
Entity Common Stock, Shares Outstanding		272,603,972
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