Statements of Consolidated Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Additional Capital Invested	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	United Airlines, Inc.	United Airlines, Inc. Additional Capital Invested	United Airlines, Inc. Retained Earnings (Accumulated Deficit)	United Airlines, Inc. Accumulated Other Comprehensive Income (Loss)	United Airlines, Inc. Payable to Parent
Balance at Dec. 31, 2020	$ 5,960	$ 8,366	$ 2,626	$ (1,139)	$ 5,928	$ 85	$ 4,939	$ (1,139)	$ 2,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,791)		(1,791)		(1,791)		(1,791)
Other comprehensive income (loss)	25			25	25			25
Stock-settled share-based compensation	100	100			100	100
Impact of UAL common stock issuance	532	532			532				532
Other					78				78
Balance at Jun. 30, 2021	4,904	9,042	804	(1,114)	4,872	185	3,148	(1,114)	2,653
Balance at Mar. 31, 2021	5,206	8,923	1,239	(1,126)	5,175	117	3,582	(1,126)	2,602
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(434)		(434)		(434)		(434)
Other comprehensive income (loss)	12			12	12			12
Stock-settled share-based compensation	68	68			68	68
Other					51				51
Balance at Jun. 30, 2021	4,904	9,042	804	(1,114)	4,872	185	3,148	(1,114)	2,653
Balance at Dec. 31, 2021	5,029	9,156	625	(942)	4,998	317	2,977	(942)	2,646
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,048)		(1,048)		(1,047)		(1,047)
Other comprehensive income (loss)	(2)			(2)	(2)			(2)
Stock-settled share-based compensation	55	55			56	56
Other					(72)				(72)
Balance at Jun. 30, 2022	3,964	8,970	(515)	(944)	3,933	373	1,930	(944)	2,574
Balance at Mar. 31, 2022	3,624	8,953	(844)	(937)	3,593	355	1,600	(937)	2,575
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	329		329		330
Other comprehensive income (loss)	(7)			(7)	(7)			(7)
Stock-settled share-based compensation	17	17			18	18
Other					(1)				(1)
Balance at Jun. 30, 2022	$ 3,964	$ 8,970	$ (515)	$ (944)	$ 3,933	$ 373	$ 1,930	$ (944)	$ 2,574