Statements of Consolidated Cash Flows (UA) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities -
Deferred income tax (benefit)	756	248	(583)
Depreciation and amortization	2,671	2,456	2,485
Operating and non-operating special charges, non-cash portion	84	16	32
Unrealized (gains) losses on investments	(27)	(20)	34
Amortization of debt discount and debt issuance costs	139	156	171
Other operating activities	6	218	222
Changes in operating assets and liabilities -
Increase in receivables	(100)	(158)	(448)
Increase in prepaids and other assets	(463)	(86)	(292)
Increase (decrease) in advance ticket sales	(851)	1,200	1,521
Increase in frequent flyer deferred revenue	468	393	307
Increase in accounts payable	572	796	985
Increase (decrease) in other liabilities	1,038	110	(403)
Net cash provided by operating activities	6,911	6,066	2,067
Investing Activities:
Capital expenditures, net of flight equipment purchase deposit returns	(7,171)	(4,819)	(2,107)
Purchases of short-term and other investments	(9,470)	(11,232)	(68)
Proceeds from sale of short-term and other investments	10,519	2,084	397
Proceeds from sale of property and equipment	39	207	107
Other, net	(23)	(69)	(1)
Net cash used in investing activities	(6,106)	(13,829)	(1,672)
Financing Activities:
Proceeds from issuance of debt and other financial liabilities, net of discounts and fees	2,388	736	11,096
Payments of long-term debt, finance leases and other financial liabilities	(4,248)	(4,011)	(5,205)
Proceeds from issuance of parent company stock	0	0	532
Net cash provided by (used in) financing activities	(1,892)	(3,349)	6,396
Net increase (decrease) in cash, cash equivalents and restricted cash	(1,087)	(11,112)	6,791
Cash, cash equivalents and restricted cash at beginning of year	7,421	18,533	11,742
Cash, cash equivalents and restricted cash at end of year	6,334	7,421	18,533
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt, finance leases and other	777	19	814
Right-of-use assets acquired through operating leases	552	137	771
Lease modifications and lease conversions	546	(84)	123
Investment interests received in exchange for goods and services	33	103	295
Cash Paid During the Period for:
Interest	1,848	1,573	1,424
Income taxes	7	8	0
United Airlines, Inc.
Operating Activities:
Net income (loss)	2,620	739	(1,962)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities -
Deferred income tax (benefit)	757	248	(583)
Depreciation and amortization	2,671	2,456	2,485
Operating and non-operating special charges, non-cash portion	84	16	32
Unrealized (gains) losses on investments	(27)	(20)	34
Amortization of debt discount and debt issuance costs	139	156	171
Other operating activities	7	218	222
Changes in operating assets and liabilities -
Increase in receivables	(100)	(158)	(448)
Increase in intercompany receivables	(33)	(76)	(28)
Increase in prepaids and other assets	(463)	(86)	(293)
Increase (decrease) in advance ticket sales	(851)	1,200	1,521
Increase in frequent flyer deferred revenue	468	393	307
Increase in accounts payable	572	796	985
Increase (decrease) in other liabilities	1,035	110	(403)
Net cash provided by operating activities	6,879	5,992	2,040
Investing Activities:
Capital expenditures, net of flight equipment purchase deposit returns	(7,171)	(4,819)	(2,107)
Purchases of short-term and other investments	(9,470)	(11,232)	(68)
Proceeds from sale of short-term and other investments	10,519	2,084	397
Proceeds from sale of property and equipment	39	207	107
Other, net	(23)	(69)	(1)
Net cash used in investing activities	(6,106)	(13,829)	(1,672)
Financing Activities:
Proceeds from issuance of debt and other financial liabilities, net of discounts and fees	2,388	736	11,096
Payments of long-term debt, finance leases and other financial liabilities	(4,248)	(4,011)	(5,205)
Proceeds from issuance of parent company stock	0	0	532
Net cash provided by (used in) financing activities	(1,860)	(3,275)	6,423
Net increase (decrease) in cash, cash equivalents and restricted cash	(1,087)	(11,112)	6,791
Cash, cash equivalents and restricted cash at beginning of year	7,421	18,533	11,742
Cash, cash equivalents and restricted cash at end of year	6,334	7,421	18,533
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt, finance leases and other	777	19	814
Right-of-use assets acquired through operating leases	552	137	771
Lease modifications and lease conversions	546	(84)	123
Investment interests received in exchange for goods and services	33	103	295
Cash Paid During the Period for:
Interest	1,848	1,573	1,424
Income taxes	$ 7	$ 8	$ 0