Statements of Consolidated Stockholders' Equity (UA) - USD ($) $ in Millions	Total	United Airlines, Inc.	Additional Capital Invested	Additional Capital Invested United Airlines, Inc.	Retained Earnings	Retained Earnings United Airlines, Inc.	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) United Airlines, Inc.	(Receivable from) Payable to Related Parties, Net United Airlines, Inc.
Balance at Dec. 31, 2020	$ 5,960	$ 5,928	$ 8,366	$ 85	$ 2,626	$ 4,939	$ (1,139)	$ (1,139)	$ 2,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,964)	(1,962)			(1,964)	(1,962)
Other comprehensive income (loss)	197	197					197	197
Stock-settled share-based compensation	232	232	232	232
Impact of UAL common stock issuance	532	532	532						532
Other		71							71
Balance at Dec. 31, 2021	5,029	4,998	9,156	317	625	2,977	(942)	(942)	2,646
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	737	739			737	739
Other comprehensive income (loss)	1,117	1,117					1,117	1,117
Stock-settled share-based compensation	86	86	86	86
Other		(75)							(75)
Balance at Dec. 31, 2022	6,896	6,865	8,986	403	1,265	3,716	175	175	2,571
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,618	2,620			2,618	2,620
Other comprehensive income (loss)	(237)	(237)					(237)	(237)
Stock-settled share-based compensation	77	77	77	77
Other		(31)		2					(33)
Balance at Dec. 31, 2023	$ 9,324	$ 9,294	$ 8,992	$ 482	$ 3,831	$ 6,336	$ (62)	$ (62)	$ 2,538