Statements of Consolidated Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Additional Capital Invested	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	United Airlines, Inc.	United Airlines, Inc. Additional Capital Invested	United Airlines, Inc. Retained Earnings	United Airlines, Inc. Accumulated Other Comprehensive Income (Loss)	United Airlines, Inc. Payable to Parent
Balance beginning 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 loss	(2)			(2)	(2)			(2)
Stock-settled share-based compensation	55	55			56	56
Other					(72)				(72)
Balance ending at Jun. 30, 2022	3,964	8,970	(515)	(944)	3,933	373	1,930	(944)	2,574
Balance beginning 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		330
Other comprehensive loss	(7)			(7)	(7)			(7)
Stock-settled share-based compensation	17	17			18	18
Other					(1)				(1)
Balance ending at Jun. 30, 2022	3,964	8,970	(515)	(944)	3,933	373	1,930	(944)	2,574
Balance beginning at Dec. 31, 2022	6,896	8,986	1,265	175	6,865	403	3,716	175	2,571
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	881		881		881		881
Other comprehensive loss	(72)			(72)	(72)			(72)
Stock-settled share-based compensation	32	32			32	32
Other					(32)				(32)
Balance ending at Jun. 30, 2023	7,705	8,945	2,095	103	7,674	435	4,597	103	2,539
Balance beginning at Mar. 31, 2023	6,668	8,926	1,020	161	6,636	414	3,522	161	2,539
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,075		1,075		1,075		1,075
Other comprehensive loss	(58)			(58)	(58)			(58)
Stock-settled share-based compensation	21	21			21	21
Other					0
Balance ending at Jun. 30, 2023	$ 7,705	$ 8,945	$ 2,095	$ 103	$ 7,674	$ 435	$ 4,597	$ 103	$ 2,539